Class Util


  • public class Util
    extends java.lang.Object
    Miscellaneous utility functions.
    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static java.nio.charset.Charset DEFAULT_CHARSET  
      private static com.google.common.cache.LoadingCache<java.lang.Class,​java.util.Map<java.lang.String,​java.lang.Enum>> ENUM_CONSTANTS
      Maps classes to the map of their enum values.
      static java.lang.String FILE_SEPARATOR
      System-dependent file separator, for example, "/" or "\."
      static java.lang.String FILE_TIMESTAMP_FORMAT
      Datetime format string for generating a timestamp string to be used as part of a filename.
      private static java.util.regex.Pattern JAVA_ID_PATTERN
      Regular expression for a valid java identifier which contains no underscores and can therefore be returned intact by toJavaId(java.lang.String, int).
      static java.lang.String LINE_SEPARATOR
      System-dependent newline character.
    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private Util()  
    • Method Summary

      All Methods Static Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      private static void appendPosixDaylightTransition​(java.util.TimeZone tz, java.lang.StringBuilder buf, int mode, int day, int month, int dayOfWeek, int time, int timeMode, boolean verbose, boolean isEnd)
      Writes a daylight savings time transition to a POSIX timezone description.
      private static void appendPosixTime​(java.lang.StringBuilder buf, int millis)
      Given a time expressed in milliseconds, append the time formatted as "hh[:mm[:ss]]".
      static <K,​V>
      java.util.Map<K,​V>
      asIndexMap​(java.util.Collection<V> values, com.google.common.base.Function<V,​K> function)
      Deprecated.
      static <K,​V>
      java.util.Map<K,​V>
      asIndexMapJ​(java.util.Collection<V> values, java.util.function.Function<V,​K> function)
      Returns a map that is a view onto a collection of values, using the provided function to convert a value to a key.
      static <K,​V>
      java.util.Map<K,​V>
      blackholeMap()
      Returns a map which ignores any write operation.
      static java.util.Calendar calendar()
      Creates a Calendar in the UTC time zone and root locale.
      static java.util.Calendar calendar​(long millis)
      Creates a Calendar in the UTC time zone and root locale with a given time.
      static <E> java.lang.Iterable<E> cast​(java.lang.Iterable<? super E> iterable, java.lang.Class<E> clazz)
      Converts an Iterable whose members are automatically down-cast to a given type.
      static <E> java.util.Iterator<E> cast​(java.util.Iterator<?> iter, java.lang.Class<E> clazz)
      Converts a iterator whose members are automatically down-cast to a given type.
      static <E> java.util.List<E> cast​(java.util.List<? super E> list, java.lang.Class<E> clazz)
      Converts a list whose members are automatically down-cast to a given type.
      static <T> java.lang.String commaList​(java.util.List<T> list)
      Converts a list of a string, with commas between elements.
      static boolean contains​(java.lang.String[] a, int length, java.lang.String s)
      Returns whether an array of strings contains a given string among the first length entries.
      static void debugCode​(java.io.PrintStream out, java.lang.String code)
      Prints the given code with line numbering.
      static <T> T deprecated​(T argument, boolean fail)
      Deprecated.
      If a piece of code calls this method, it indicates that the code needs to be cleaned up.
      private static java.lang.String digits3​(long x, int z)  
      static void discard​(boolean b)
      Does nothing with its argument.
      static void discard​(double d)
      Does nothing with its argument.
      static void discard​(int i)
      Does nothing with its argument.
      static void discard​(java.lang.Object o)
      Does nothing with its argument.
      static <E> java.util.List<E> distinctList​(java.lang.Iterable<E> keys)
      Converts an iterable into a list with unique elements.
      static <E> java.util.List<E> distinctList​(java.util.List<E> list)
      Converts a list into a list with unique elements.
      static <T extends java.lang.Enum<T>>
      java.util.Map<java.lang.String,​T>
      enumConstants​(java.lang.Class<T> clazz)
      Creates a map of the values of an enumeration by name.
      static <T extends java.lang.Enum<T>>
      T
      enumVal​(java.lang.Class<T> clazz, java.lang.String name)
      Returns the value of an enumeration with a particular name.
      static <T extends java.lang.Enum<T>>
      T
      enumVal​(T default_, java.lang.String name)
      Returns the value of an enumeration with a particular or default value if not found.
      static <T> boolean equalShallow​(java.util.List<? extends T> list0, java.util.List<? extends T> list1)
      Returns whether two lists are equal to each other using shallow comparisons.
      static <E> java.lang.Iterable<E> filter​(java.lang.Iterable<?> iterable, java.lang.Class<E> includeFilter)
      Makes a collection of untyped elements appear as a list of strictly typed elements, by filtering out those which are not of the correct type.
      static <E> java.lang.Iterable<E> filter​(java.lang.Iterable<E> iterable, java.util.function.Predicate<E> predicate)
      Filters an iterable.
      static <E> java.util.Collection<E> filter​(java.util.Collection<?> collection, java.lang.Class<E> includeFilter)  
      static <E> java.util.Iterator<E> filter​(java.util.Iterator<E> iterator, java.util.function.Predicate<E> predicate)
      Filters an iterator.
      static <E> java.util.List<E> filter​(java.util.List<?> list, java.lang.Class<E> includeFilter)
      Returns a subset of a list containing only elements of a given type.
      static int findMatch​(java.util.List<java.lang.String> strings, java.lang.String seek, boolean caseSensitive)
      Looks for a string within a list of strings, using a given case-sensitivity policy, and returns the position at which the first match is found, or -1 if there are no matches.
      static boolean first​(java.lang.Boolean v0, boolean v1)
      Unboxes a Boolean value, using a given default value if it is null.
      static byte first​(java.lang.Byte v0, byte v1)
      Unboxes a Byte value, using a given default value if it is null.
      static char first​(java.lang.Character v0, char v1)
      Unboxes a Character value, using a given default value if it is null.
      static double first​(java.lang.Double v0, double v1)
      Unboxes a Double value, using a given default value if it is null.
      static float first​(java.lang.Float v0, float v1)
      Unboxes a Float value, using a given default value if it is null.
      static int first​(java.lang.Integer v0, int v1)
      Unboxes a Integer value, using a given default value if it is null.
      static long first​(java.lang.Long v0, long v1)
      Unboxes a Long value, using a given default value if it is null.
      static short first​(java.lang.Short v0, short v1)
      Unboxes a Short value, using a given default value if it is null.
      static <T> T first​(T v0, T v1)
      Returns the first value if it is not null, otherwise the second value.
      static <E> int firstDuplicate​(java.util.List<E> list)
      Returns the ordinal of the first element in the list which is equal to a previous element in the list.
      static java.nio.charset.Charset getDefaultCharset()
      Returns the Charset object representing the value of CalciteSystemProperty.DEFAULT_CHARSET
      static java.lang.String getFileTimestamp()
      Deprecated.
      static java.lang.String getMessages​(java.lang.Throwable t)
      Deprecated.
      static java.lang.String getStackTrace​(java.lang.Throwable t)
      Deprecated.
      Use Throwables.getStackTraceAsString(Throwable)
      static int hash​(int i, int j)
      Deprecated.
      Use Objects.hash(Object...)
      static int hash​(int h, java.lang.Object o)
      Deprecated.
      Use Objects.hash(Object...)
      static int hashArray​(int h, java.lang.Object[] a)
      Deprecated.
      Use Objects.hash(Object...)
      static int hashCode​(double v)
      static java.lang.String human​(double d)
      Converts a number into human-readable form, with 3 digits and a "K", "M" or "G" multiplier for thousands, millions or billions.
      static <E> java.util.List<java.util.List<E>> immutableCopy​(java.lang.Iterable<? extends java.lang.Iterable<E>> lists)
      Returns a copy of a list of lists, making the component lists immutable if they are not already.
      static <E> boolean intersects​(java.util.Collection<E> c0, java.util.Collection<E> c1)
      Returns whether two collections have any elements in common.
      static <E> boolean isDistinct​(java.util.List<E> list)
      Returns whether the elements of list are distinct.
      static boolean isNullOrEmpty​(java.lang.String s)  
      static boolean isSingleValue​(SqlCall call)
      Does nothing with its argument.
      static boolean isValidJavaIdentifier​(java.lang.String s)
      Returns true when input string is a valid Java identifier.
      static <E> E last​(java.util.List<E> list)
      Returns the last element of a list.
      static <E> java.util.List<E> last​(java.util.List<E> list, int n)
      Returns the last n elements of a list.
      static java.lang.String lines​(java.lang.Iterable<java.lang.String> strings)
      Converts a list of strings to a string separated by newlines.
      static java.lang.String listToString​(java.util.List<java.lang.String> list)
      Converts ["ab", "c"] to "ab"."c".
      static <K,​V>
      java.util.Map<K,​V>
      mapOf​(K key, V value, java.lang.Object... keyValues)
      Returns a hashmap with given contents.
      static boolean matches​(boolean caseSensitive, java.lang.String s0, java.lang.String s1)
      Returns whether a name matches another according to a given case-sensitivity policy.
      static <T> java.util.Set<T> minus​(java.util.Set<T> set1, java.util.Set<T> set2)
      Returns a set of the elements which are in set1 but not in set2, without modifying either.
      static java.lang.RuntimeException needToImplement​(java.lang.Object o)
      Returns a RuntimeException indicating that a particular feature has not been implemented, but should be.
      static java.lang.Error newInternal()
      Deprecated.
      Throw new AssertionError
      static java.lang.Error newInternal​(java.lang.String s)
      Deprecated.
      Throw new AssertionError
      static java.lang.Error newInternal​(java.lang.Throwable e)
      Deprecated.
      Throw new RuntimeException if checked; throw raw exception if unchecked or Error
      static java.lang.Error newInternal​(java.lang.Throwable e, java.lang.String s)
      Deprecated.
      Throw new AssertionError if applicable; or RuntimeException if e is checked; or raw exception if e is unchecked or Error.
      static double nLogN​(double d)
      Computes nlogn(n) using the natural logarithm (or n if n < Math.E, so the result is never negative.
      static <T> java.lang.Iterable<T> orEmpty​(java.lang.Iterable<T> v0)  
      static <E> java.util.List<Pair<E,​E>> pairs​(java.util.List<E> list)
      Given a list with N elements [e0, e1, ..., eN-1] (where N is even), returns a list of the N / 2 elements [ (e0, e1), (e2, e3), ...
      static java.util.Locale parseLocale​(java.lang.String localeString)
      Parses a locale string.
      static void permAssert​(boolean b, java.lang.String description)
      Deprecated.
      Use Preconditions.checkArgument(boolean)
      static void post​(boolean b, java.lang.String description)
      Deprecated.
      Use Preconditions.checkArgument(boolean) or Objects.requireNonNull(Object)
      static void pre​(boolean b, java.lang.String description)
      Deprecated.
      Use Preconditions.checkArgument(boolean) or Objects.requireNonNull(Object)
      static void print​(java.io.PrintWriter pw, java.lang.Object o)
      Prints an object using reflection.
      static void print​(java.io.PrintWriter pw, java.lang.Object o, int indent)  
      static void printJavaString​(java.lang.Appendable appendable, java.lang.String s, boolean nullMeansNull)
      Prints a string, enclosing in double quotes (") and escaping if necessary.
      static void println​(java.io.PrintWriter pw, java.lang.Object o)  
      static java.io.PrintWriter printWriter​(java.io.File file)
      Creates a PrintWriter to a given file using UTF-8 character set.
      static java.io.PrintWriter printWriter​(java.io.OutputStream out)
      Creates a PrintWriter to a given output stream using UTF-8 character set.
      static <E> java.util.List<E> quotientList​(java.util.List<E> list, int n, int k)
      Creates a list that returns every nth element of a list, starting at element k.
      static java.util.List<java.lang.Integer> range​(int end)  
      static java.util.List<java.lang.Integer> range​(int start, int end)  
      static java.lang.String readAllAsString​(java.io.Reader reader)
      Deprecated.
      static java.io.BufferedReader reader​(java.io.File file)
      Creates a BufferedReader to read a given file using UTF-8 character set.
      static java.io.BufferedReader reader​(java.io.InputStream in)
      Creates a BufferedReader to a given input stream using UTF-8 character set.
      static java.lang.String replace​(java.lang.String s, java.lang.String find, java.lang.String replace)
      Replaces every occurrence of find in s with replace.
      static java.lang.String rpad​(java.lang.String s, int len)
      Deprecated.
      Use Spaces.padRight(String, int)
      static java.lang.String rtrim​(java.lang.String s)
      Deprecated.
      static <E> java.util.List<E> select​(java.util.List<E> list, java.util.List<java.lang.Integer> ordinals)
      Returns a view of a list, picking the elements of a list with the given set of ordinals.
      static <T> java.lang.String sepList​(java.util.List<T> list, java.lang.String sep)
      Converts a list of a string, with a given separator between elements.
      static <E> java.util.List<E> skip​(java.util.List<E> list)
      Returns all but the first element of a list.
      static <E> java.util.List<E> skip​(java.util.List<E> list, int fromIndex)
      Returns all but the first n elements of a list.
      static <E> java.util.List<E> skipLast​(java.util.List<E> list)
      Returns every element of a list but its last element.
      static <E> java.util.List<E> skipLast​(java.util.List<E> list, int n)
      Returns every element of a list but its last n elements.
      static void squelchConnection​(java.sql.Connection connection)
      Deprecated.
      static void squelchJar​(java.util.jar.JarFile jar)
      Deprecated.
      static void squelchReader​(java.io.Reader reader)
      Deprecated.
      static void squelchStmt​(java.sql.Statement stmt)
      Deprecated.
      static void squelchStream​(java.io.InputStream stream)
      Deprecated.
      static void squelchStream​(java.io.OutputStream stream)
      Deprecated.
      static void squelchWriter​(java.io.Writer writer)
      Deprecated.
      static <E> boolean startsWith​(java.util.List<E> list0, java.util.List<E> list1)
      Returns whether one list is a prefix of another.
      static java.util.List<java.lang.String> stringToList​(java.lang.String s)  
      static java.lang.String stripDoubleQuotes​(java.lang.String value)
      Converts double-quoted Java strings to their contents.
      static void swallow​(java.lang.Throwable e, org.slf4j.Logger logger)
      Records that an exception has been caught but will not be re-thrown.
      static void throwIfUnchecked​(java.lang.Throwable throwable)
      As Throwables.throwIfUnchecked(Throwable), which was introduced in Guava 20, but we don't require Guava version 20 yet.
      static <T> java.util.stream.Collector<T,​com.google.common.collect.ImmutableList.Builder<T>,​com.google.common.collect.ImmutableList<T>> toImmutableList()
      Returns a Collector that accumulates the input elements into a Guava ImmutableList via a ImmutableList.Builder.
      static java.lang.String toJavaId​(java.lang.String s, int ordinal)
      Converts an arbitrary string into a string suitable for use as a Java identifier.
      static java.lang.Iterable<java.lang.String> tokenize​(java.lang.String s, java.lang.String delim)
      Converts a string into tokens.
      static java.lang.String toLinux​(java.lang.String s)  
      static <T> java.util.List<T> toList​(java.util.Iterator<T> iter)
      Deprecated.
      static java.util.Map<java.lang.String,​java.lang.String> toMap​(java.util.Properties properties)
      Converts a Properties object to a Map<String, String>.
      static java.lang.String toPosix​(java.util.TimeZone tz, boolean verbose)
      Converts a Java timezone to POSIX format, so that the boost C++ library can instantiate timezone objects.
      static java.lang.String toScientificNotation​(java.math.BigDecimal bd)
      Formats a BigDecimal value to a string in scientific notation For example
      A value of 0.00001234 would be formated as 1.234E-5 A value of 100000.00 would be formated as 1.00E5 A value of 100 (scale zero) would be formated as 1E2
      static <T> java.lang.String toString​(java.lang.Iterable<T> iterable, java.lang.String start, java.lang.String sep, java.lang.String end)
      Converts an iterable to a string.
      static java.lang.RuntimeException toUnchecked​(java.lang.Exception e)
      Wraps an exception with RuntimeException and return it.
      static java.net.URL toURL​(java.io.File file)
      Deprecated.
      static <F,​T>
      java.util.List<T>
      transform​(java.util.List<F> list, java.util.function.Function<F,​T> function)
      Transforms a list, applying a function to each element.
      static <E extends java.lang.Enum<E>>
      java.lang.Error
      unexpected​(E value)
      Returns an exception indicating that we didn't expect to find this enumeration here.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • LINE_SEPARATOR

        public static final java.lang.String LINE_SEPARATOR
        System-dependent newline character.

        In general, you should not use this in expected results of tests. Expected results should be the expected result on Linux (or Mac OS) using '\n'. Apply toLinux(String) to Windows actual results, if necessary, to make them look like Linux actual.

      • FILE_SEPARATOR

        public static final java.lang.String FILE_SEPARATOR
        System-dependent file separator, for example, "/" or "\."
      • FILE_TIMESTAMP_FORMAT

        public static final java.lang.String FILE_TIMESTAMP_FORMAT
        Datetime format string for generating a timestamp string to be used as part of a filename. Conforms to SimpleDateFormat conventions.
        See Also:
        Constant Field Values
      • JAVA_ID_PATTERN

        private static final java.util.regex.Pattern JAVA_ID_PATTERN
        Regular expression for a valid java identifier which contains no underscores and can therefore be returned intact by toJavaId(java.lang.String, int).
      • DEFAULT_CHARSET

        private static final java.nio.charset.Charset DEFAULT_CHARSET
      • ENUM_CONSTANTS

        private static final com.google.common.cache.LoadingCache<java.lang.Class,​java.util.Map<java.lang.String,​java.lang.Enum>> ENUM_CONSTANTS
        Maps classes to the map of their enum values. Uses a weak map so that classes are not prevented from being unloaded.
    • Constructor Detail

      • Util

        private Util()
    • Method Detail

      • isSingleValue

        public static boolean isSingleValue​(SqlCall call)
        Does nothing with its argument. Returns whether it is ensured that the call produces a single value
        Parameters:
        call - the expression to evaluate
        Returns:
        Whether it is ensured that the call produces a single value
      • discard

        public static void discard​(java.lang.Object o)
        Does nothing with its argument. Call this method when you have a value you are not interested in, but you don't want the compiler to warn that you are not using it.
      • discard

        public static void discard​(int i)
        Does nothing with its argument. Call this method when you have a value you are not interested in, but you don't want the compiler to warn that you are not using it.
      • discard

        public static void discard​(boolean b)
        Does nothing with its argument. Call this method when you have a value you are not interested in, but you don't want the compiler to warn that you are not using it.
      • discard

        public static void discard​(double d)
        Does nothing with its argument. Call this method when you have a value you are not interested in, but you don't want the compiler to warn that you are not using it.
      • swallow

        public static void swallow​(java.lang.Throwable e,
                                   org.slf4j.Logger logger)
        Records that an exception has been caught but will not be re-thrown. If the tracer is not null, logs the exception to the tracer.
        Parameters:
        e - Exception
        logger - If not null, logs exception to this logger
      • equalShallow

        public static <T> boolean equalShallow​(java.util.List<? extends T> list0,
                                               java.util.List<? extends T> list1)
        Returns whether two lists are equal to each other using shallow comparisons.
        Parameters:
        list0 - First list
        list1 - Second list
        Returns:
        Whether lists are same length and all of their elements are equal using == (may be null).
      • hash

        @Deprecated
        public static int hash​(int i,
                               int j)
        Deprecated.
        Use Objects.hash(Object...)
        Combines two integers into a hash code.
      • hash

        @Deprecated
        public static int hash​(int h,
                               java.lang.Object o)
        Deprecated.
        Use Objects.hash(Object...)
        Computes a hash code from an existing hash code and an object (which may be null).
      • hashArray

        @Deprecated
        public static int hashArray​(int h,
                                    java.lang.Object[] a)
        Deprecated.
        Use Objects.hash(Object...)
        Computes a hash code from an existing hash code and an array of objects (which may be null).
      • hashCode

        @Deprecated
        public static int hashCode​(double v)
        Computes the hash code of a double value. Equivalent to Double.hashCode(double), but that method was only introduced in JDK 1.8.
        Parameters:
        v - Value
        Returns:
        Hash code
      • minus

        public static <T> java.util.Set<T> minus​(java.util.Set<T> set1,
                                                 java.util.Set<T> set2)
        Returns a set of the elements which are in set1 but not in set2, without modifying either.
      • nLogN

        public static double nLogN​(double d)
        Computes nlogn(n) using the natural logarithm (or n if n < Math.E, so the result is never negative.
      • print

        public static void print​(java.io.PrintWriter pw,
                                 java.lang.Object o)
        Prints an object using reflection. We can handle null; arrays of objects and primitive values; for regular objects, we print all public fields.
      • print

        public static void print​(java.io.PrintWriter pw,
                                 java.lang.Object o,
                                 int indent)
      • printJavaString

        public static void printJavaString​(java.lang.Appendable appendable,
                                           java.lang.String s,
                                           boolean nullMeansNull)
        Prints a string, enclosing in double quotes (") and escaping if necessary. For examples, printDoubleQuoted(w,"x\"y",false) prints "x\"y".

        The appendable where the value is printed must not incur I/O operations. This method is not meant to be used for writing the values to permanent storage.

        Throws:
        java.lang.IllegalStateException - if the print to the specified appendable fails due to I/O
      • println

        public static void println​(java.io.PrintWriter pw,
                                   java.lang.Object o)
      • toScientificNotation

        public static java.lang.String toScientificNotation​(java.math.BigDecimal bd)
        Formats a BigDecimal value to a string in scientific notation For example
        • A value of 0.00001234 would be formated as 1.234E-5
        • A value of 100000.00 would be formated as 1.00E5
        • A value of 100 (scale zero) would be formated as 1E2

        If bd has a precision higher than 20, this method will truncate the output string to have a precision of 20 (no rounding will be done, just a truncate).

      • replace

        public static java.lang.String replace​(java.lang.String s,
                                               java.lang.String find,
                                               java.lang.String replace)
        Replaces every occurrence of find in s with replace.
      • toURL

        @Deprecated
        public static java.net.URL toURL​(java.io.File file)
                                  throws java.net.MalformedURLException
        Deprecated.
        Creates a file-protocol URL for the given file.
        Throws:
        java.net.MalformedURLException
      • getFileTimestamp

        @Deprecated
        public static java.lang.String getFileTimestamp()
        Deprecated.
        Gets a timestamp string for use in file names. The generated timestamp string reflects the current time.
      • stripDoubleQuotes

        public static java.lang.String stripDoubleQuotes​(java.lang.String value)
        Converts double-quoted Java strings to their contents. For example, "foo\"bar" becomes foo"bar.
      • toJavaId

        public static java.lang.String toJavaId​(java.lang.String s,
                                                int ordinal)
        Converts an arbitrary string into a string suitable for use as a Java identifier.

        The mapping is one-to-one (that is, distinct strings will produce distinct java identifiers). The mapping is also reversible, but the inverse mapping is not implemented.

        A valid Java identifier must start with a Unicode letter, underscore, or dollar sign ($). The other characters, if any, can be a Unicode letter, underscore, dollar sign, or digit.

        This method uses an algorithm similar to URL encoding. Valid characters are unchanged; invalid characters are converted to an underscore followed by the hex code of the character; and underscores are doubled.

        Examples:

        • toJavaId("foo") returns "foo"
        • toJavaId("foo bar") returns "foo_20_bar"
        • toJavaId("foo_bar") returns "foo__bar"
        • toJavaId("0bar") returns "_40_bar" (digits are illegal as a prefix)
        • toJavaId("foo0bar") returns "foo0bar"
      • isValidJavaIdentifier

        public static boolean isValidJavaIdentifier​(java.lang.String s)
        Returns true when input string is a valid Java identifier.
        Parameters:
        s - input string
        Returns:
        true when input string is a valid Java identifier
      • toLinux

        public static java.lang.String toLinux​(java.lang.String s)
      • toList

        @Deprecated
        public static <T> java.util.List<T> toList​(java.util.Iterator<T> iter)
        Deprecated.
        Materializes the results of a Iterator as a List.
        Parameters:
        iter - iterator to materialize
        Returns:
        materialized list
      • isNullOrEmpty

        public static boolean isNullOrEmpty​(java.lang.String s)
        Returns:
        true if s==null or if s.length()==0
      • commaList

        public static <T> java.lang.String commaList​(java.util.List<T> list)
        Converts a list of a string, with commas between elements.

        For example, commaList(Arrays.asList({"a", "b"})) returns "a, b".

        Parameters:
        list - List
        Returns:
        String representation of string
      • sepList

        public static <T> java.lang.String sepList​(java.util.List<T> list,
                                                   java.lang.String sep)
        Converts a list of a string, with a given separator between elements.
      • getDefaultCharset

        public static java.nio.charset.Charset getDefaultCharset()
        Returns the Charset object representing the value of CalciteSystemProperty.DEFAULT_CHARSET
        Throws:
        java.nio.charset.IllegalCharsetNameException - If the given charset name is illegal
        java.nio.charset.UnsupportedCharsetException - If no support for the named charset is available in this instance of the Java virtual machine
      • newInternal

        @Deprecated
        public static java.lang.Error newInternal()
        Deprecated.
        Throw new AssertionError
      • newInternal

        @Deprecated
        public static java.lang.Error newInternal​(java.lang.String s)
        Deprecated.
        Throw new AssertionError
      • newInternal

        @Deprecated
        public static java.lang.Error newInternal​(java.lang.Throwable e)
        Deprecated.
        Throw new RuntimeException if checked; throw raw exception if unchecked or Error
      • newInternal

        public static java.lang.Error newInternal​(java.lang.Throwable e,
                                                  java.lang.String s)
        Deprecated.
        Throw new AssertionError if applicable; or RuntimeException if e is checked; or raw exception if e is unchecked or Error.
      • throwIfUnchecked

        public static void throwIfUnchecked​(java.lang.Throwable throwable)
        As Throwables.throwIfUnchecked(Throwable), which was introduced in Guava 20, but we don't require Guava version 20 yet.
      • toUnchecked

        public static java.lang.RuntimeException toUnchecked​(java.lang.Exception e)
        Wraps an exception with RuntimeException and return it. If the exception is already an instance of RuntimeException, returns it directly.
      • getMessages

        @Deprecated
        public static java.lang.String getMessages​(java.lang.Throwable t)
        Deprecated.
        Retrieves messages in a exception and writes them to a string. In the string returned, each message will appear on a different line.
        Returns:
        a non-null string containing all messages of the exception
      • getStackTrace

        @Deprecated
        public static java.lang.String getStackTrace​(java.lang.Throwable t)
        Deprecated.
        Use Throwables.getStackTraceAsString(Throwable)
        Returns the stack trace of a throwable. Called from native code.
        Parameters:
        t - Throwable
        Returns:
        Stack trace
      • pre

        @Deprecated
        public static void pre​(boolean b,
                               java.lang.String description)
        Deprecated.
        Use Preconditions.checkArgument(boolean) or Objects.requireNonNull(Object)
      • post

        @Deprecated
        public static void post​(boolean b,
                                java.lang.String description)
        Deprecated.
        Use Preconditions.checkArgument(boolean) or Objects.requireNonNull(Object)
      • permAssert

        @Deprecated
        public static void permAssert​(boolean b,
                                      java.lang.String description)
        Deprecated.
        Use Preconditions.checkArgument(boolean)
      • needToImplement

        public static java.lang.RuntimeException needToImplement​(java.lang.Object o)
        Returns a RuntimeException indicating that a particular feature has not been implemented, but should be.

        If every 'hole' in our functionality uses this method, it will be easier for us to identity the holes. Throwing a UnsupportedOperationException isn't as good, because sometimes we actually want to partially implement an API.

        Example usage:

        class MyVisitor extends BaseVisitor {
             void accept(Foo foo) {
                 // Exception will identify which subclass forgot to override
                 // this method
                 throw Util.needToImplement(this);
             }
         }
        Parameters:
        o - The object which was the target of the call, or null. Passing the object gives crucial information if a method needs to be overridden and a subclass forgot to do so.
        Returns:
        an UnsupportedOperationException.
      • deprecated

        public static <T> T deprecated​(T argument,
                                       boolean fail)
        Deprecated.
        If a piece of code calls this method, it indicates that the code needs to be cleaned up.
        Flags a piece of code as needing to be cleaned up before you check in.

        Introduce a call to this method to indicate that a piece of code, or a javadoc comment, needs work before you check in. If you have an IDE which can easily trace references, this is an easy way to maintain a to-do list.

        Checked-in code must never call this method: you must remove all calls/references to this method before you check in.

        The argument has generic type and determines the type of the result. This allows you to use the method inside an expression, for example

        int x = Util.deprecated(0, false);

        but the usual usage is to pass in a descriptive string.

        Examples

        Example #1: Using deprecated to fail if a piece of supposedly dead code is reached

        void foo(int x) {
             if (x < 0) {
                 // If this code is executed, an error will be thrown.
                 Util.deprecated(
                     "no longer need to handle negative numbers", true);
                 bar(x);
             } else {
                 baz(x);
             }
         }

        Example #2: Using deprecated to comment out dead code

        if (Util.deprecated(false, false)) {
             // This code will not be executed, but an error will not be thrown.
             baz();
         }
        Parameters:
        argument - Arbitrary argument to the method.
        fail - Whether to throw an exception if this method is called
        Returns:
        The value of the argument.
      • contains

        public static boolean contains​(java.lang.String[] a,
                                       int length,
                                       java.lang.String s)
        Returns whether an array of strings contains a given string among the first length entries.
        Parameters:
        a - Array of strings
        length - Number of entries to search
        s - String to seek
        Returns:
        Whether array contains the name
      • readAllAsString

        @Deprecated
        public static java.lang.String readAllAsString​(java.io.Reader reader)
                                                throws java.io.IOException
        Deprecated.
        Reads all remaining contents from a Reader and returns them as a string.
        Parameters:
        reader - reader to read from
        Returns:
        reader contents as string
        Throws:
        java.io.IOException
      • squelchJar

        @Deprecated
        public static void squelchJar​(java.util.jar.JarFile jar)
        Deprecated.
        Closes a Jar, ignoring any I/O exception. This should only be used in finally blocks when it's necessary to avoid throwing an exception which might mask a real exception.
        Parameters:
        jar - jar to close
      • squelchStream

        @Deprecated
        public static void squelchStream​(java.io.InputStream stream)
        Deprecated.
        Closes an InputStream, ignoring any I/O exception. This should only be used in finally blocks when it's necessary to avoid throwing an exception which might mask a real exception.
        Parameters:
        stream - stream to close
      • squelchStream

        @Deprecated
        public static void squelchStream​(java.io.OutputStream stream)
        Deprecated.
        Closes an OutputStream, ignoring any I/O exception. This should only be used in finally blocks when it's necessary to avoid throwing an exception which might mask a real exception. If you want to make sure that data has been successfully flushed, do NOT use this anywhere else; use stream.close() instead.
        Parameters:
        stream - stream to close
      • squelchReader

        @Deprecated
        public static void squelchReader​(java.io.Reader reader)
        Deprecated.
        Closes a Reader, ignoring any I/O exception. This should only be used in finally blocks when it's necessary to avoid throwing an exception which might mask a real exception.
        Parameters:
        reader - reader to close
      • squelchWriter

        @Deprecated
        public static void squelchWriter​(java.io.Writer writer)
        Deprecated.
        Closes a Writer, ignoring any I/O exception. This should only be used in finally blocks when it's necessary to avoid throwing an exception which might mask a real exception. If you want to make sure that data has been successfully flushed, do NOT use this anywhere else; use writer.close() instead.
        Parameters:
        writer - writer to close
      • squelchStmt

        @Deprecated
        public static void squelchStmt​(java.sql.Statement stmt)
        Deprecated.
        Closes a Statement, ignoring any SQL exception. This should only be used in finally blocks when it's necessary to avoid throwing an exception which might mask a real exception.
        Parameters:
        stmt - stmt to close
      • squelchConnection

        @Deprecated
        public static void squelchConnection​(java.sql.Connection connection)
        Deprecated.
        Closes a Connection, ignoring any SQL exception. This should only be used in finally blocks when it's necessary to avoid throwing an exception which might mask a real exception.
        Parameters:
        connection - connection to close
      • rtrim

        @Deprecated
        public static java.lang.String rtrim​(java.lang.String s)
        Deprecated.
        Trims trailing spaces from a string.
        Parameters:
        s - string to be trimmed
        Returns:
        trimmed string
      • rpad

        @Deprecated
        public static java.lang.String rpad​(java.lang.String s,
                                            int len)
        Deprecated.
        Use Spaces.padRight(String, int)
        Pads a string with spaces up to a given length.
        Parameters:
        s - string to be padded
        len - desired length
        Returns:
        padded string
      • toString

        public static <T> java.lang.String toString​(java.lang.Iterable<T> iterable,
                                                    java.lang.String start,
                                                    java.lang.String sep,
                                                    java.lang.String end)
        Converts an iterable to a string.
      • lines

        public static java.lang.String lines​(java.lang.Iterable<java.lang.String> strings)
        Converts a list of strings to a string separated by newlines.
      • tokenize

        public static java.lang.Iterable<java.lang.String> tokenize​(java.lang.String s,
                                                                    java.lang.String delim)
        Converts a string into tokens.
      • toPosix

        public static java.lang.String toPosix​(java.util.TimeZone tz,
                                               boolean verbose)
        Converts a Java timezone to POSIX format, so that the boost C++ library can instantiate timezone objects.

        POSIX IEEE 1003.1 defines a format for timezone specifications.

        The boost C++ library can read these specifications and instantiate posix_time_zone objects from them. The purpose of this method, therefore, is to allow the C++ code such as the fennel calculator to use the same notion of timezone as Java code.

        The format is as follows:

        "std offset dst [offset],start[/time],end[/time]"

        where:

        • 'std' specifies the abbrev of the time zone.
        • 'offset' is the offset from UTC, and takes the form [+|-]hh[:mm[:ss]] {h=0-23, m/s=0-59}
        • 'dst' specifies the abbrev of the time zone during daylight savings time
        • The second offset is how many hours changed during DST. Default=1
        • 'start' and 'end' are the dates when DST goes into (and out of) effect.

          They can each be one of three forms:
          1. Mm.w.d {month=1-12, week=1-5 (5 is always last), day=0-6}
          2. Jn {n=1-365 Feb29 is never counted}
          3. n {n=0-365 Feb29 is counted in leap years}
        • 'time' has the same format as 'offset', and defaults to 02:00:00.

        For example:

        • "PST-8PDT01:00:00,M4.1.0/02:00:00,M10.1.0/02:00:00"; or more tersely
        • "PST-8PDT,M4.1.0,M10.1.0"

        (Real format strings do not contain spaces; they are in the above template only for readability.)

        Boost apparently diverges from the POSIX standard in how it treats the sign of timezone offsets. The POSIX standard states 'If preceded by a '-', the timezone shall be east of the Prime Meridian; otherwise, it shall be west', yet boost requires the opposite. For instance, PST has offset '-8' above. This method generates timezone strings consistent with boost's expectations.

        Parameters:
        tz - Timezone
        verbose - Whether to include fields which can be omitted because they have their default values
        Returns:
        Timezone in POSIX format (offset sign reversed, per boost's idiosyncracies)
      • appendPosixDaylightTransition

        private static void appendPosixDaylightTransition​(java.util.TimeZone tz,
                                                          java.lang.StringBuilder buf,
                                                          int mode,
                                                          int day,
                                                          int month,
                                                          int dayOfWeek,
                                                          int time,
                                                          int timeMode,
                                                          boolean verbose,
                                                          boolean isEnd)
        Writes a daylight savings time transition to a POSIX timezone description.
        Parameters:
        tz - Timezone
        buf - Buffer to append to
        mode - Transition mode
        day - Day of transition
        month - Month of transition
        dayOfWeek - Day of week of transition
        time - Time of transition in millis
        timeMode - Mode of time transition
        verbose - Verbose
        isEnd - Whether this transition is leaving DST
      • appendPosixTime

        private static void appendPosixTime​(java.lang.StringBuilder buf,
                                            int millis)
        Given a time expressed in milliseconds, append the time formatted as "hh[:mm[:ss]]".
        Parameters:
        buf - Buffer to append to
        millis - Milliseconds
      • parseLocale

        public static java.util.Locale parseLocale​(java.lang.String localeString)
        Parses a locale string.

        The inverse operation of Locale.toString().

        Parameters:
        localeString - Locale string, e.g. "en" or "en_US"
        Returns:
        Java locale object
      • cast

        public static <E> java.util.List<E> cast​(java.util.List<? super E> list,
                                                 java.lang.Class<E> clazz)
        Converts a list whose members are automatically down-cast to a given type.

        If a member of the backing list is not an instanceof E, the accessing method (such as List.get(int)) will throw a ClassCastException.

        All modifications are automatically written to the backing list. Not synchronized.

        Parameters:
        list - Backing list.
        clazz - Class to cast to.
        Returns:
        A list whose members are of the desired type.
      • cast

        public static <E> java.util.Iterator<E> cast​(java.util.Iterator<?> iter,
                                                     java.lang.Class<E> clazz)
        Converts a iterator whose members are automatically down-cast to a given type.

        If a member of the backing iterator is not an instanceof E, Iterator.next()) will throw a ClassCastException.

        All modifications are automatically written to the backing iterator. Not synchronized.

        Parameters:
        iter - Backing iterator.
        clazz - Class to cast to.
        Returns:
        An iterator whose members are of the desired type.
      • cast

        public static <E> java.lang.Iterable<E> cast​(java.lang.Iterable<? super E> iterable,
                                                     java.lang.Class<E> clazz)
        Converts an Iterable whose members are automatically down-cast to a given type.

        All modifications are automatically written to the backing iterator. Not synchronized.

        Parameters:
        iterable - Backing iterable
        clazz - Class to cast to
        Returns:
        An iterable whose members are of the desired type.
      • filter

        public static <E> java.lang.Iterable<E> filter​(java.lang.Iterable<?> iterable,
                                                       java.lang.Class<E> includeFilter)
        Makes a collection of untyped elements appear as a list of strictly typed elements, by filtering out those which are not of the correct type.

        The returned object is an Iterable, which makes it ideal for use with the 'foreach' construct. For example,

        List<Number> numbers = Arrays.asList(1, 2, 3.14, 4, null, 6E23);
        for (int myInt : filter(numbers, Integer.class)) {
            print(i);
        }

        will print 1, 2, 4.

        Parameters:
        iterable - Iterable
        includeFilter - Class whose instances to include
      • filter

        public static <E> java.util.Collection<E> filter​(java.util.Collection<?> collection,
                                                         java.lang.Class<E> includeFilter)
      • filter

        public static <E> java.util.List<E> filter​(java.util.List<?> list,
                                                   java.lang.Class<E> includeFilter)
        Returns a subset of a list containing only elements of a given type.

        Modifications to the list are NOT written back to the source list.

        Parameters:
        list - List of objects
        includeFilter - Class to filter for
        Returns:
        List of objects of given class (or a subtype)
      • toMap

        public static java.util.Map<java.lang.String,​java.lang.String> toMap​(java.util.Properties properties)
        Converts a Properties object to a Map<String, String>.

        This is necessary because Properties is a dinosaur class. It ought to extend Map<String,String>, but instead extends Hashtable<Object,Object>.

        Typical usage, to iterate over a Properties:

        Properties properties;
        for (Map.Entry<String, String> entry = Util.toMap(properties).entrySet()) {
        println("key=" + entry.getKey() + ", value=" + entry.getValue());
        }
      • mapOf

        public static <K,​V> java.util.Map<K,​V> mapOf​(K key,
                                                                 V value,
                                                                 java.lang.Object... keyValues)
        Returns a hashmap with given contents.

        Use this method in initializers. Type parameters are inferred from context, and the contents are initialized declaratively. For example,

        Map<String, Integer> population =
          Olap4jUtil.mapOf(
            "UK", 65000000,
            "USA", 300000000);
        Type Parameters:
        K - Key type
        V - Value type
        Parameters:
        key - First key
        value - First value
        keyValues - Second and sequent key/value pairs
        Returns:
        Map with given contents
      • unexpected

        public static <E extends java.lang.Enum<E>> java.lang.Error unexpected​(E value)
        Returns an exception indicating that we didn't expect to find this enumeration here.
        Parameters:
        value - Enumeration value which was not expected
        Returns:
        an error, to be thrown
      • enumConstants

        public static <T extends java.lang.Enum<T>> java.util.Map<java.lang.String,​T> enumConstants​(java.lang.Class<T> clazz)
        Creates a map of the values of an enumeration by name.
        Parameters:
        clazz - Enumeration class
        Returns:
        map of values
      • enumVal

        public static <T extends java.lang.Enum<T>> T enumVal​(java.lang.Class<T> clazz,
                                                              java.lang.String name)
        Returns the value of an enumeration with a particular name.

        Similar to Enum.valueOf(Class, String), but returns null rather than throwing IllegalArgumentException.

        Type Parameters:
        T - Enum class type
        Parameters:
        clazz - Enum class
        name - Name of enum constant
        Returns:
        Enum constant or null
      • enumVal

        public static <T extends java.lang.Enum<T>> T enumVal​(T default_,
                                                              java.lang.String name)
        Returns the value of an enumeration with a particular or default value if not found.
        Type Parameters:
        T - Enum class type
        Parameters:
        default_ - Default value (not null)
        name - Name of enum constant
        Returns:
        Enum constant, never null
      • quotientList

        public static <E> java.util.List<E> quotientList​(java.util.List<E> list,
                                                         int n,
                                                         int k)
        Creates a list that returns every nth element of a list, starting at element k.

        It is OK if the list is empty or its size is not a multiple of n.

        For instance, quotientList(list, 2, 0) returns the even elements of a list, and quotientList(list, 2, 1) returns the odd elements. Those lists are the same length only if list has even size.

      • pairs

        public static <E> java.util.List<Pair<E,​E>> pairs​(java.util.List<E> list)
        Given a list with N elements [e0, e1, ..., eN-1] (where N is even), returns a list of the N / 2 elements [ (e0, e1), (e2, e3), ... ].
      • first

        public static <T> T first​(T v0,
                                  T v1)
        Returns the first value if it is not null, otherwise the second value.

        The result may be null.

        Equivalent to the Elvis operator (?:) of languages such as Groovy or PHP.

      • first

        public static double first​(java.lang.Double v0,
                                   double v1)
        Unboxes a Double value, using a given default value if it is null.
      • first

        public static float first​(java.lang.Float v0,
                                  float v1)
        Unboxes a Float value, using a given default value if it is null.
      • first

        public static int first​(java.lang.Integer v0,
                                int v1)
        Unboxes a Integer value, using a given default value if it is null.
      • first

        public static long first​(java.lang.Long v0,
                                 long v1)
        Unboxes a Long value, using a given default value if it is null.
      • first

        public static boolean first​(java.lang.Boolean v0,
                                    boolean v1)
        Unboxes a Boolean value, using a given default value if it is null.
      • first

        public static short first​(java.lang.Short v0,
                                  short v1)
        Unboxes a Short value, using a given default value if it is null.
      • first

        public static char first​(java.lang.Character v0,
                                 char v1)
        Unboxes a Character value, using a given default value if it is null.
      • first

        public static byte first​(java.lang.Byte v0,
                                 byte v1)
        Unboxes a Byte value, using a given default value if it is null.
      • orEmpty

        public static <T> java.lang.Iterable<T> orEmpty​(java.lang.Iterable<T> v0)
      • last

        public static <E> E last​(java.util.List<E> list)
        Returns the last element of a list.
        Throws:
        java.lang.IndexOutOfBoundsException - if the list is empty
      • skipLast

        public static <E> java.util.List<E> skipLast​(java.util.List<E> list)
        Returns every element of a list but its last element.
      • skipLast

        public static <E> java.util.List<E> skipLast​(java.util.List<E> list,
                                                     int n)
        Returns every element of a list but its last n elements.
      • last

        public static <E> java.util.List<E> last​(java.util.List<E> list,
                                                 int n)
        Returns the last n elements of a list.
      • skip

        public static <E> java.util.List<E> skip​(java.util.List<E> list)
        Returns all but the first element of a list.
      • skip

        public static <E> java.util.List<E> skip​(java.util.List<E> list,
                                                 int fromIndex)
        Returns all but the first n elements of a list.
      • range

        public static java.util.List<java.lang.Integer> range​(int end)
      • range

        public static java.util.List<java.lang.Integer> range​(int start,
                                                              int end)
      • isDistinct

        public static <E> boolean isDistinct​(java.util.List<E> list)
        Returns whether the elements of list are distinct.
      • firstDuplicate

        public static <E> int firstDuplicate​(java.util.List<E> list)
        Returns the ordinal of the first element in the list which is equal to a previous element in the list.

        For example, firstDuplicate(Arrays.asList("a", "b", "c", "b", "a")) returns 3, the ordinal of the 2nd "b".

        Parameters:
        list - List
        Returns:
        Ordinal of first duplicate, or -1 if not found
      • distinctList

        public static <E> java.util.List<E> distinctList​(java.util.List<E> list)
        Converts a list into a list with unique elements.

        The order is preserved; the second and subsequent occurrences are removed.

        If the list is already unique it is returned unchanged.

      • distinctList

        public static <E> java.util.List<E> distinctList​(java.lang.Iterable<E> keys)
        Converts an iterable into a list with unique elements.

        The order is preserved; the second and subsequent occurrences are removed.

        If iterable is a unique list it is returned unchanged.

      • intersects

        public static <E> boolean intersects​(java.util.Collection<E> c0,
                                             java.util.Collection<E> c1)
        Returns whether two collections have any elements in common.
      • findMatch

        public static int findMatch​(java.util.List<java.lang.String> strings,
                                    java.lang.String seek,
                                    boolean caseSensitive)
        Looks for a string within a list of strings, using a given case-sensitivity policy, and returns the position at which the first match is found, or -1 if there are no matches.
      • matches

        public static boolean matches​(boolean caseSensitive,
                                      java.lang.String s0,
                                      java.lang.String s1)
        Returns whether a name matches another according to a given case-sensitivity policy.
      • startsWith

        public static <E> boolean startsWith​(java.util.List<E> list0,
                                             java.util.List<E> list1)
        Returns whether one list is a prefix of another.
      • listToString

        public static java.lang.String listToString​(java.util.List<java.lang.String> list)
        Converts ["ab", "c"] to "ab"."c".
      • stringToList

        public static java.util.List<java.lang.String> stringToList​(java.lang.String s)
      • human

        public static java.lang.String human​(double d)
        Converts a number into human-readable form, with 3 digits and a "K", "M" or "G" multiplier for thousands, millions or billions.

        Examples: -2, 0, 1, 999, 1.00K, 1.99K, 3.45M, 4.56B.

      • digits3

        private static java.lang.String digits3​(long x,
                                                int z)
      • asIndexMapJ

        public static <K,​V> java.util.Map<K,​V> asIndexMapJ​(java.util.Collection<V> values,
                                                                       java.util.function.Function<V,​K> function)
        Returns a map that is a view onto a collection of values, using the provided function to convert a value to a key.

        Unlike Maps.uniqueIndex(Iterable, com.google.common.base.Function), returns a view whose contents change as the collection of values changes.

        Type Parameters:
        K - Key type
        V - Value type
        Parameters:
        values - Collection of values
        function - Function to map value to key
        Returns:
        Map that is a view onto the values
      • asIndexMap

        @Deprecated
        public static <K,​V> java.util.Map<K,​V> asIndexMap​(java.util.Collection<V> values,
                                                                      com.google.common.base.Function<V,​K> function)
        Deprecated.
      • debugCode

        public static void debugCode​(java.io.PrintStream out,
                                     java.lang.String code)
        Prints the given code with line numbering.
      • immutableCopy

        public static <E> java.util.List<java.util.List<E>> immutableCopy​(java.lang.Iterable<? extends java.lang.Iterable<E>> lists)
        Returns a copy of a list of lists, making the component lists immutable if they are not already.
      • printWriter

        public static java.io.PrintWriter printWriter​(java.io.OutputStream out)
        Creates a PrintWriter to a given output stream using UTF-8 character set.

        Does not use the default character set.

      • printWriter

        public static java.io.PrintWriter printWriter​(java.io.File file)
                                               throws java.io.FileNotFoundException
        Creates a PrintWriter to a given file using UTF-8 character set.

        Does not use the default character set.

        Throws:
        java.io.FileNotFoundException
      • reader

        public static java.io.BufferedReader reader​(java.io.InputStream in)
        Creates a BufferedReader to a given input stream using UTF-8 character set.

        Does not use the default character set.

      • reader

        public static java.io.BufferedReader reader​(java.io.File file)
                                             throws java.io.FileNotFoundException
        Creates a BufferedReader to read a given file using UTF-8 character set.

        Does not use the default character set.

        Throws:
        java.io.FileNotFoundException
      • calendar

        public static java.util.Calendar calendar()
        Creates a Calendar in the UTC time zone and root locale. Does not use the time zone or locale.
      • calendar

        public static java.util.Calendar calendar​(long millis)
        Creates a Calendar in the UTC time zone and root locale with a given time.
      • toImmutableList

        public static <T> java.util.stream.Collector<T,​com.google.common.collect.ImmutableList.Builder<T>,​com.google.common.collect.ImmutableList<T>> toImmutableList()
        Returns a Collector that accumulates the input elements into a Guava ImmutableList via a ImmutableList.Builder.

        It will be obsolete when we move to Guava 21.0, which has ImmutableList.toImmutableList().

        Type Parameters:
        T - Type of the input elements
        Returns:
        a Collector that collects all the input elements into an ImmutableList, in encounter order
      • transform

        public static <F,​T> java.util.List<T> transform​(java.util.List<F> list,
                                                              java.util.function.Function<F,​T> function)
        Transforms a list, applying a function to each element.
      • filter

        public static <E> java.lang.Iterable<E> filter​(java.lang.Iterable<E> iterable,
                                                       java.util.function.Predicate<E> predicate)
        Filters an iterable.
      • filter

        public static <E> java.util.Iterator<E> filter​(java.util.Iterator<E> iterator,
                                                       java.util.function.Predicate<E> predicate)
        Filters an iterator.
      • select

        public static <E> java.util.List<E> select​(java.util.List<E> list,
                                                   java.util.List<java.lang.Integer> ordinals)
        Returns a view of a list, picking the elements of a list with the given set of ordinals.
      • blackholeMap

        public static <K,​V> java.util.Map<K,​V> blackholeMap()
        Returns a map which ignores any write operation.