Package org.ethelred.util.collect

Class Sequences

java.lang.Object
org.ethelred.util.collect.Sequences
public class Sequences extends Object
Utility functions for Lists.

  • Method Details

    • prefixes

      public static <T> List<List<T>> prefixes(Iterable<T> iterable)
      Get all possible prefixes of an Iterable. For example, if the parameter is a list [1,2,3], the result will be [[],[1],[1,2],[1,2,3]].
      Type Parameters:
      T - the type of elements
      Parameters:
      iterable - The starting value
      Returns:
      A list of lists

    • concat

      public static <T, C extends Collection<T>> C concat(Collection<? extends T> a, Collection<? extends T> b, IntFunction<C> collectionSupplier)
      Join two Collections into one.
      Type Parameters:
      T - the type of elements
      C - the type of Collection to return
      Parameters:
      a - first collection
      b - second collection
      collectionSupplier - Function to construct the collection to return. The int parameter is the expected size of the resulting collection.
      Returns:
      the combined collection

    • concat

      public static <T> List<T> concat(List<? extends T> a, List<? extends T> b)
      Join two Lists into one. The order will be all elements of a followed by all elements of b.
      Type Parameters:
      T - the type of elements
      Parameters:
      a - first list
      b - second list
      Returns:
      Combined list

    • concat

      @SafeVarargs public static <T> List<T> concat(List<? extends T> list, T... items)
      Join some items to the end of a List.
      Type Parameters:
      T - the type of elements
      Parameters:
      list - original list
      items - items to add to the list
      Returns:
      Combined list

    • head

      public static <T> List<T> head(List<T> list, int items)
      Retrieve items from the start of a List.
      Type Parameters:
      T - the type of elements
      Parameters:
      list - list to draw from
      items - When positive, return that many items from the start. When negative, return items from the start of the list except for that number at the end. When 0, return an empty list, though I'm not sure why you would want to do that. If greater than the size of the list, the original list is returned.
      Returns:
      resulting list

    • tail

      public static <T> List<T> tail(List<T> list, int items)
      Like head, except it works backwards from the end of the list.