Package it.tidalwave.util

Class CollectionUtils

  • public final class CollectionUtils
extends java.lang.Object
    This class contains a bunch of utility methods for manipulating lists.
    Since:
    3.2-ALPHA-13
    Author:
    Fabrizio Giudici
    Status: stable API

    • Constructor Summary

      Constructors 
      Constructor Description
      CollectionUtils()  

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static <T> java.util.List<T> concat​(java.util.List<? extends T> list1, java.util.List<? extends T> list2)
      Appends a list to another.
      static <T> java.util.List<T> concat​(java.util.List<? extends T> list, T object)
      Appends a list to an object.
      static <T> T head​(java.util.List<? extends T> list)
      Returns the first element of a list.
      static <T> java.util.Optional<T> optionalHead​(java.util.List<? extends T> list)
      Returns the (optional) first element of a list.
      static <T> java.util.List<T> reversed​(java.util.List<? extends T> list)
      Reverses a list.
      static <T extends java.lang.Comparable<? super T>>
      java.util.List<T>      		 sorted​(java.util.List<? extends T> list)
      Sorts a list.
      static <T> java.util.List<T> sorted​(java.util.List<? extends T> list, java.util.Comparator<? super T> comparator)
      Sorts a list with a given Comparator.
      static <T> java.util.List<T> tail​(java.util.List<? extends T> list)
      Returns the tail element of a list, that is a list without the first element.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • CollectionUtils

        public CollectionUtils()

    • Method Detail

      • concat

        @Nonnull
public static <T> java.util.List<T> concat​(@Nonnull
                                           java.util.List<? extends T> list,
                                           @Nonnull
                                           T object)
        Appends a list to an object. The resulting list is mutable.
        Type Parameters:
        T - the type of list items
        Parameters:
        list - the list
        object - the list to append
        Returns:
        the list with the appended object

      • concat

        @Nonnull
public static <T> java.util.List<T> concat​(@Nonnull
                                           java.util.List<? extends T> list1,
                                           @Nonnull
                                           java.util.List<? extends T> list2)
        Appends a list to another. The resulting list is mutable.
        Type Parameters:
        T - the type of list items
        Parameters:
        list1 - the former list
        list2 - the latter list
        Returns:
        the list with the appended object

      • reversed

        @Nonnull
public static <T> java.util.List<T> reversed​(@Nonnull
                                             java.util.List<? extends T> list)
        Reverses a list. The resulting list is mutable.
        Type Parameters:
        T - the type of list items
        Parameters:
        list - the list
        Returns:
        the reversed list

      • sorted

        @Nonnull
public static <T extends java.lang.Comparable<? super T>> java.util.List<T> sorted​(@Nonnull
                                                                                   java.util.List<? extends T> list)
        Sorts a list. The resulting list is mutable.
        Type Parameters:
        T - the type of list items
        Parameters:
        list - the list
        Returns:
        the sorted list
        Since:
        3.2-ALPHA-13

      • sorted

        @Nonnull
public static <T> java.util.List<T> sorted​(@Nonnull
                                           java.util.List<? extends T> list,
                                           @Nonnull
                                           java.util.Comparator<? super T> comparator)
        Sorts a list with a given Comparator. The resulting list is mutable.
        Type Parameters:
        T - the type of list items
        Parameters:
        list - the list
        comparator - the comparator
        Returns:
        the sorted list
        Since:
        3.2-ALPHA-13

      • optionalHead

        @Nonnull
public static <T> java.util.Optional<T> optionalHead​(@Nonnull
                                                     java.util.List<? extends T> list)
        Returns the (optional) first element of a list.
        Type Parameters:
        T - the type of list items
        Parameters:
        list - the list
        Returns:
        the first element

      • head

        @Nonnull
public static <T> T head​(@Nonnull
                         java.util.List<? extends T> list)
        Returns the first element of a list.
        Type Parameters:
        T - the type of list items
        Parameters:
        list - the list (cannot be empty)
        Returns:
        the first element
        Throws:
        java.lang.IllegalArgumentException - if the list is empty

      • tail

        @Nonnull
public static <T> java.util.List<T> tail​(@Nonnull
                                         java.util.List<? extends T> list)
        Returns the tail element of a list, that is a list without the first element. The tail of an empty list is an empty list. The resulting list is mutable.
        Type Parameters:
        T - the type of list items
        Parameters:
        list - the list
        Returns:
        the tail of the list