Package it.unimi.dsi.fastutil.ints

Class IntArrayList

java.lang.Object
java.util.AbstractCollection<java.lang.Integer>
it.unimi.dsi.fastutil.ints.AbstractIntCollection
it.unimi.dsi.fastutil.ints.AbstractIntList
it.unimi.dsi.fastutil.ints.IntArrayList
All Implemented Interfaces:
IntCollection, IntIterable, IntList, IntStack, Stack<java.lang.Integer>, java.io.Serializable, java.lang.Cloneable, java.lang.Comparable<java.util.List<? extends java.lang.Integer>>, java.lang.Iterable<java.lang.Integer>, java.util.Collection<java.lang.Integer>, java.util.List<java.lang.Integer>, java.util.RandomAccess
public class IntArrayList
extends AbstractIntList
implements java.util.RandomAccess, java.lang.Cloneable, java.io.Serializable
A type-specific array-based list; provides some additional methods that use polymorphism to avoid (un)boxing.

This class implements a lightweight, fast, open, optimized, reuse-oriented version of array-based lists. Instances of this class represent a list with an array that is enlarged as needed when new entries are created (by increasing its current length by 50%), but is never made smaller (even on a clear()). A family of trimming methods lets you control the size of the backing array; this is particularly useful if you reuse instances of this class. Range checks are equivalent to those of java.util's classes, but they are delayed as much as possible. The backing array is exposed by the elements() method.

This class implements the bulk methods removeElements(), addElements() and getElements() using high-performance system calls (e.g., System.arraycopy()) instead of expensive loops.

See Also:
ArrayList, Serialized Form

  • Nested Class Summary

    Nested classes/interfaces inherited from class it.unimi.dsi.fastutil.ints.AbstractIntList

    AbstractIntList.IntRandomAccessSubList, AbstractIntList.IntSubList

  • Field Summary

    Fields
    Modifier and Type Field Description
    static int DEFAULT_INITIAL_CAPACITY
    The initial default capacity of an array list.

  • Constructor Summary

    Constructors
    Constructor Description
    IntArrayList()
    Creates a new array list with DEFAULT_INITIAL_CAPACITY capacity.
    IntArrayList​(int capacity)
    Creates a new array list with given capacity.
    IntArrayList​(int[] a)
    Creates a new array list and fills it with the elements of a given array.
    IntArrayList​(int[] a, int offset, int length)
    Creates a new array list and fills it with the elements of a given array.
    IntArrayList​(IntCollection c)
    Creates a new array list and fills it with a given type-specific collection.
    IntArrayList​(IntIterator i)
    Creates a new array list and fills it with the elements returned by a type-specific iterator..
    IntArrayList​(IntList l)
    Creates a new array list and fills it with a given type-specific list.
    IntArrayList​(java.util.Collection<? extends java.lang.Integer> c)
    Creates a new array list and fills it with a given collection.
    IntArrayList​(java.util.Iterator<? extends java.lang.Integer> i)
    Creates a new array list and fills it with the elements returned by an iterator..

  • Method Summary

    Modifier and Type Method Description
    boolean add​(int k)
    Ensures that this collection contains the specified element (optional operation).
    void add​(int index, int k)
    Inserts the specified element at the specified position in this list (optional operation).
    boolean addAll​(int index, IntCollection c)
    Inserts all of the elements in the specified type-specific collection into this type-specific list at the specified position (optional operation).
    boolean addAll​(int index, IntList l)
    Inserts all of the elements in the specified type-specific list into this type-specific list at the specified position (optional operation).
    void addElements​(int index, int[] a, int offset, int length)
    Adds elements to this type-specific list using optimized system calls.
    void clear()
    IntArrayList clone()  
    int compareTo​(IntArrayList l)
    Compares this array list to another array list.
    int compareTo​(java.util.List<? extends java.lang.Integer> l)
    Compares this list to another object.
    int[] elements()
    Returns the backing array of this list.
    void ensureCapacity​(int capacity)
    Ensures that this array list can contain the given number of entries without resizing.
    boolean equals​(IntArrayList l)
    Compares this type-specific array list to another one.
    boolean equals​(java.lang.Object o)  
    void forEach​(java.util.function.IntConsumer action)
    Performs the given action for each element of this type-specific Iterable until all elements have been processed or the action throws an exception.
    void getElements​(int from, int[] a, int offset, int length)
    Copies element of this type-specific list into the given array using optimized system calls.
    int getInt​(int index)
    Returns the element at the specified position in this list.
    int indexOf​(int k)
    Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
    boolean isEmpty()
    Checks whether the stack is empty.
    int lastIndexOf​(int k)
    Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
    IntListIterator listIterator​(int index)
    Returns a type-specific list iterator on the list starting at a given index.
    static IntArrayList of()
    Creates a new empty array list.
    static IntArrayList of​(int... init)
    Creates an array list using an array of elements.
    boolean rem​(int k)
    Removes a single instance of the specified element from this collection, if it is present (optional operation).
    boolean removeAll​(IntCollection c)
    Remove from this collection all elements in the given type-specific collection.
    void removeElements​(int from, int to)
    Removes elements of this type-specific list using optimized system calls.
    int removeInt​(int index)
    Removes the element at the specified position in this list (optional operation).
    int set​(int index, int k)
    Replaces the element at the specified position in this list with the specified element (optional operation).
    void setElements​(int index, int[] a, int offset, int length)
    Sets elements to this type-specific list using optimized system calls.
    int size()  
    void size​(int size)
    Sets the size of this list.
    void sort​(IntComparator comp)
    Sort a list using a type-specific comparator.
    IntSpliterator spliterator()
    Returns a type-specific spliterator on the elements of this list.
    IntList subList​(int from, int to)
    Returns a type-specific view of the portion of this list from the index from, inclusive, to the index to, exclusive.
    int[] toArray​(int[] a)
    Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.
    static IntArrayList toList​(java.util.stream.IntStream stream)
    Collects the result of a primitive Stream into a new ArrayList.
    static IntArrayList toListWithExpectedSize​(java.util.stream.IntStream stream, int expectedSize)
    Collects the result of a primitive Stream into a new ArrayList, potentially pre-allocated to handle the given size.
    void trim()
    Trims this array list so that the capacity is equal to the size.
    void trim​(int n)
    Trims the backing array if it is too large.
    void unstableSort​(IntComparator comp)
    Sorts this list using a sort not assured to be stable.
    static IntArrayList wrap​(int[] a)
    Wraps a given array into an array list.
    static IntArrayList wrap​(int[] a, int length)
    Wraps a given array into an array list of given size.

    Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntList

    addAll, addAll, addAll, addElements, contains, hashCode, iterator, listIterator, peekInt, popInt, push, replaceAll, toIntArray, topInt, toString

    Methods inherited from class it.unimi.dsi.fastutil.ints.AbstractIntCollection

    add, contains, containsAll, containsAll, forEach, remove, removeAll, removeIf, retainAll, retainAll, toIntArray

    Methods inherited from class java.util.AbstractCollection

    toArray, toArray

    Methods inherited from class java.lang.Object

    getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.util.Collection

    toArray

    Methods inherited from interface it.unimi.dsi.fastutil.ints.IntCollection

    containsAll, intIterator, intParallelStream, intSpliterator, intStream, parallelStream, removeIf, removeIf, removeIf, retainAll, stream, toIntArray

    Methods inherited from interface it.unimi.dsi.fastutil.ints.IntIterable

    forEach, forEach

    Methods inherited from interface it.unimi.dsi.fastutil.ints.IntList

    add, add, addAll, contains, get, indexOf, lastIndexOf, remove, remove, replaceAll, replaceAll, set, setElements, setElements, sort, unstableSort

    Methods inherited from interface it.unimi.dsi.fastutil.ints.IntStack

    peek, pop, push, top

    Methods inherited from interface java.util.List

    containsAll, removeAll, retainAll, toArray, toArray

  • Field Details

    • DEFAULT_INITIAL_CAPACITY

      public static final int DEFAULT_INITIAL_CAPACITY
      The initial default capacity of an array list.
      See Also:
      Constant Field Values

  • Constructor Details

    • IntArrayList

      public IntArrayList​(int capacity)
      Creates a new array list with given capacity.
      Parameters:
      capacity - the initial capacity of the array list (may be 0).

    • IntArrayList

      public IntArrayList()
      Creates a new array list with DEFAULT_INITIAL_CAPACITY capacity.

    • IntArrayList

      public IntArrayList​(java.util.Collection<? extends java.lang.Integer> c)
      Creates a new array list and fills it with a given collection.
      Parameters:
      c - a collection that will be used to fill the array list.

    • IntArrayList

      public IntArrayList​(IntCollection c)
      Creates a new array list and fills it with a given type-specific collection.
      Parameters:
      c - a type-specific collection that will be used to fill the array list.

    • IntArrayList

      public IntArrayList​(IntList l)
      Creates a new array list and fills it with a given type-specific list.
      Parameters:
      l - a type-specific list that will be used to fill the array list.

    • IntArrayList

      public IntArrayList​(int[] a)
      Creates a new array list and fills it with the elements of a given array.
      Parameters:
      a - an array whose elements will be used to fill the array list.

    • IntArrayList

      public IntArrayList​(int[] a, int offset, int length)
      Creates a new array list and fills it with the elements of a given array.
      Parameters:
      a - an array whose elements will be used to fill the array list.
      offset - the first element to use.
      length - the number of elements to use.

    • IntArrayList

      public IntArrayList​(java.util.Iterator<? extends java.lang.Integer> i)
      Creates a new array list and fills it with the elements returned by an iterator..
      Parameters:
      i - an iterator whose returned elements will fill the array list.

    • IntArrayList

      public IntArrayList​(IntIterator i)
      Creates a new array list and fills it with the elements returned by a type-specific iterator..
      Parameters:
      i - a type-specific iterator whose returned elements will fill the array list.

  • Method Details

    • elements

      public int[] elements()
      Returns the backing array of this list.
      Returns:
      the backing array.

    • wrap

      public static IntArrayList wrap​(int[] a, int length)
      Wraps a given array into an array list of given size.

      Note it is guaranteed that the type of the array returned by elements() will be the same (see the comments in the class documentation).

      Parameters:
      a - an array to wrap.
      length - the length of the resulting array list.
      Returns:
      a new array list of the given size, wrapping the given array.

    • wrap

      public static IntArrayList wrap​(int[] a)
      Wraps a given array into an array list.

      Note it is guaranteed that the type of the array returned by elements() will be the same (see the comments in the class documentation).

      Parameters:
      a - an array to wrap.
      Returns:
      a new array list wrapping the given array.

    • of

      public static IntArrayList of()
      Creates a new empty array list.
      Returns:
      a new empty array list.

    • of

      public static IntArrayList of​(int... init)
      Creates an array list using an array of elements.
      Parameters:
      init - a the array the will become the new backing array of the array list.
      Returns:
      a new array list backed by the given array.
      See Also:
      wrap(int[], int)

    • toList

      public static IntArrayList toList​(java.util.stream.IntStream stream)
      Collects the result of a primitive Stream into a new ArrayList.

      This method performs a terminal operation on the given Stream

      API Notes:
      Taking a primitive stream instead of returning something like a Collector is necessary because there is no primitive Collector equivalent in the Java API.

    • toListWithExpectedSize

      public static IntArrayList toListWithExpectedSize​(java.util.stream.IntStream stream, int expectedSize)
      Collects the result of a primitive Stream into a new ArrayList, potentially pre-allocated to handle the given size.

      This method performs a terminal operation on the given Stream

      API Notes:
      Taking a primitive stream instead returning something like a Collector is necessary because there is no primitive Collector equivalent in the Java API.

    • ensureCapacity

      public void ensureCapacity​(int capacity)
      Ensures that this array list can contain the given number of entries without resizing.
      Parameters:
      capacity - the new minimum capacity for this array list.

    • add

      public void add​(int index, int k)
      Description copied from class: AbstractIntList
      Inserts the specified element at the specified position in this list (optional operation).
      Specified by:
      add in interface IntList
      Overrides:
      add in class AbstractIntList
      See Also:
      List.add(int,Object)

    • add

      public boolean add​(int k)
      Description copied from class: AbstractIntList
      Ensures that this collection contains the specified element (optional operation).
      Specified by:
      add in interface IntCollection
      Specified by:
      add in interface IntList
      Overrides:
      add in class AbstractIntList
      See Also:
      Collection.add(Object)

    • getInt

      public int getInt​(int index)
      Description copied from interface: IntList
      Returns the element at the specified position in this list.
      Specified by:
      getInt in interface IntList
      See Also:
      List.get(int)

    • indexOf

      public int indexOf​(int k)
      Description copied from interface: IntList
      Returns the index of the first occurrence of the specified element in this list, or -1 if this list does not contain the element.
      Specified by:
      indexOf in interface IntList
      Overrides:
      indexOf in class AbstractIntList
      See Also:
      List.indexOf(Object)

    • lastIndexOf

      public int lastIndexOf​(int k)
      Description copied from interface: IntList
      Returns the index of the last occurrence of the specified element in this list, or -1 if this list does not contain the element.
      Specified by:
      lastIndexOf in interface IntList
      Overrides:
      lastIndexOf in class AbstractIntList
      See Also:
      List.lastIndexOf(Object)

    • removeInt

      public int removeInt​(int index)
      Description copied from class: AbstractIntList
      Removes the element at the specified position in this list (optional operation).
      Specified by:
      removeInt in interface IntList
      Overrides:
      removeInt in class AbstractIntList
      See Also:
      List.remove(int)

    • rem

      public boolean rem​(int k)
      Description copied from class: AbstractIntList
      Removes a single instance of the specified element from this collection, if it is present (optional operation).
      Specified by:
      rem in interface IntCollection
      Overrides:
      rem in class AbstractIntList
      See Also:
      List.remove(Object)

    • set

      public int set​(int index, int k)
      Description copied from class: AbstractIntList
      Replaces the element at the specified position in this list with the specified element (optional operation).
      Specified by:
      set in interface IntList
      Overrides:
      set in class AbstractIntList
      See Also:
      List.set(int,Object)

    • clear

      public void clear()
      Description copied from class: AbstractIntList
      Specified by:
      clear in interface java.util.Collection<java.lang.Integer>
      Specified by:
      clear in interface java.util.List<java.lang.Integer>
      Overrides:
      clear in class AbstractIntList

    • size

      public int size()
      Specified by:
      size in interface java.util.Collection<java.lang.Integer>
      Specified by:
      size in interface java.util.List<java.lang.Integer>
      Specified by:
      size in class java.util.AbstractCollection<java.lang.Integer>

    • size

      public void size​(int size)
      Description copied from interface: IntList
      Sets the size of this list.

      If the specified size is smaller than the current size, the last elements are discarded. Otherwise, they are filled with 0/null/false.

      Specified by:
      size in interface IntList
      Overrides:
      size in class AbstractIntList
      Parameters:
      size - the new size.

    • isEmpty

      public boolean isEmpty()
      Description copied from interface: Stack
      Checks whether the stack is empty.
      Specified by:
      isEmpty in interface java.util.Collection<java.lang.Integer>
      Specified by:
      isEmpty in interface java.util.List<java.lang.Integer>
      Specified by:
      isEmpty in interface Stack<java.lang.Integer>
      Overrides:
      isEmpty in class java.util.AbstractCollection<java.lang.Integer>
      Returns:
      true if the stack is empty.

    • trim

      public void trim()
      Trims this array list so that the capacity is equal to the size.
      See Also:
      ArrayList.trimToSize()

    • trim

      public void trim​(int n)
      Trims the backing array if it is too large. If the current array length is smaller than or equal to n, this method does nothing. Otherwise, it trims the array length to the maximum between n and size().

      This method is useful when reusing lists. Clearing a list leaves the array length untouched. If you are reusing a list many times, you can call this method with a typical size to avoid keeping around a very large array just because of a few large transient lists.

      Parameters:
      n - the threshold for the trimming.

    • subList

      public IntList subList​(int from, int to)
      Description copied from interface: IntList
      Returns a type-specific view of the portion of this list from the index from, inclusive, to the index to, exclusive.
      Specified by:
      subList in interface IntList
      Specified by:
      subList in interface java.util.List<java.lang.Integer>
      Overrides:
      subList in class AbstractIntList
      See Also:
      List.subList(int,int)

    • getElements

      public void getElements​(int from, int[] a, int offset, int length)
      Copies element of this type-specific list into the given array using optimized system calls.
      Specified by:
      getElements in interface IntList
      Overrides:
      getElements in class AbstractIntList
      Parameters:
      from - the start index (inclusive).
      a - the destination array.
      offset - the offset into the destination array where to store the first element copied.
      length - the number of elements to be copied.

    • removeElements

      public void removeElements​(int from, int to)
      Removes elements of this type-specific list using optimized system calls.
      Specified by:
      removeElements in interface IntList
      Overrides:
      removeElements in class AbstractIntList
      Parameters:
      from - the start index (inclusive).
      to - the end index (exclusive).

    • addElements

      public void addElements​(int index, int[] a, int offset, int length)
      Adds elements to this type-specific list using optimized system calls.
      Specified by:
      addElements in interface IntList
      Overrides:
      addElements in class AbstractIntList
      Parameters:
      index - the index at which to add elements.
      a - the array containing the elements.
      offset - the offset of the first element to add.
      length - the number of elements to add.

    • setElements

      public void setElements​(int index, int[] a, int offset, int length)
      Sets elements to this type-specific list using optimized system calls.
      Specified by:
      setElements in interface IntList
      Overrides:
      setElements in class AbstractIntList
      Parameters:
      index - the index at which to start setting elements.
      a - the array containing the elements.
      offset - the offset of the first element to add.
      length - the number of elements to add.

    • forEach

      public void forEach​(java.util.function.IntConsumer action)
      Description copied from class: AbstractIntList
      Performs the given action for each element of this type-specific Iterable until all elements have been processed or the action throws an exception.
      Specified by:
      forEach in interface IntIterable
      Overrides:
      forEach in class AbstractIntList
      Parameters:
      action - the action to be performed for each element.
      See Also:
      Iterable.forEach(java.util.function.Consumer)

    • addAll

      public boolean addAll​(int index, IntCollection c)
      Description copied from interface: IntList
      Inserts all of the elements in the specified type-specific collection into this type-specific list at the specified position (optional operation).
      Specified by:
      addAll in interface IntList
      Overrides:
      addAll in class AbstractIntList
      See Also:
      List.addAll(int,java.util.Collection)

    • addAll

      public boolean addAll​(int index, IntList l)
      Description copied from interface: IntList
      Inserts all of the elements in the specified type-specific list into this type-specific list at the specified position (optional operation).
      Specified by:
      addAll in interface IntList
      See Also:
      List.addAll(int,Collection)

    • removeAll

      public boolean removeAll​(IntCollection c)
      Description copied from interface: IntCollection
      Remove from this collection all elements in the given type-specific collection.
      Specified by:
      removeAll in interface IntCollection
      Overrides:
      removeAll in class AbstractIntCollection
      Parameters:
      c - a type-specific collection.
      Returns:
      true if this collection changed as a result of the call.
      See Also:
      Collection.removeAll(Collection)

    • toArray

      public int[] toArray​(int[] a)
      Description copied from interface: IntCollection
      Returns an array containing all of the elements in this collection; the runtime type of the returned array is that of the specified array.

      Note that, contrarily to Collection.toArray(Object[]), this methods just writes all elements of this collection: no special value will be added after the last one.

      Specified by:
      toArray in interface IntCollection
      Overrides:
      toArray in class AbstractIntList
      Parameters:
      a - if this array is big enough, it will be used to store this collection.
      Returns:
      a primitive type array containing the items of this collection.
      See Also:
      Collection.toArray(Object[])

    • listIterator

      public IntListIterator listIterator​(int index)
      Description copied from class: AbstractIntList
      Returns a type-specific list iterator on the list starting at a given index.
      Specified by:
      listIterator in interface IntList
      Specified by:
      listIterator in interface java.util.List<java.lang.Integer>
      Overrides:
      listIterator in class AbstractIntList
      See Also:
      List.listIterator(int)

    • spliterator

      public IntSpliterator spliterator()
      Returns a type-specific spliterator on the elements of this list.

      List spliterators must report at least Spliterator.SIZED and Spliterator.ORDERED.

      See List.spliterator() for more documentation on the requirements of the returned spliterator.

      The returned spliterator is late-binding; it will track structural changes after the current index, up until the first trySplit(), at which point the maximum index will be fixed.
      Structural changes before the current index or after the first trySplit() will result in unspecified behavior.

      Specified by:
      spliterator in interface java.util.Collection<java.lang.Integer>
      Specified by:
      spliterator in interface IntCollection
      Specified by:
      spliterator in interface IntIterable
      Specified by:
      spliterator in interface IntList
      Specified by:
      spliterator in interface java.lang.Iterable<java.lang.Integer>
      Specified by:
      spliterator in interface java.util.List<java.lang.Integer>
      Returns:
      a type-specific spliterator on the elements of this collection.

    • sort

      public void sort​(IntComparator comp)
      Description copied from interface: IntList
      Sort a list using a type-specific comparator.

      Pass null to sort using natural ordering.

      Specified by:
      sort in interface IntList
      See Also:
      List.sort(java.util.Comparator)

    • unstableSort

      public void unstableSort​(IntComparator comp)
      Description copied from interface: IntList
      Sorts this list using a sort not assured to be stable.

      Pass null to sort using natural ordering.

      This differs from List.sort(java.util.Comparator) in that the results are not assured to be stable, but may be a bit faster.

      Unless a subclass specifies otherwise, the results of the method if the list is concurrently modified during the sort are unspecified.

      Specified by:
      unstableSort in interface IntList

    • clone

      public IntArrayList clone()

    • equals

      public boolean equals​(IntArrayList l)
      Compares this type-specific array list to another one.
      Parameters:
      l - a type-specific array list.
      Returns:
      true if the argument contains the same elements of this type-specific array list.
      API Notes:
      This method exists only for sake of efficiency. The implementation inherited from the abstract implementation would already work.

    • equals

      public boolean equals​(java.lang.Object o)
      Specified by:
      equals in interface java.util.Collection<java.lang.Integer>
      Specified by:
      equals in interface java.util.List<java.lang.Integer>
      Overrides:
      equals in class AbstractIntList

    • compareTo

      public int compareTo​(IntArrayList l)
      Compares this array list to another array list.
      Parameters:
      l - an array list.
      Returns:
      a negative integer, zero, or a positive integer as this list is lexicographically less than, equal to, or greater than the argument.
      API Notes:
      This method exists only for sake of efficiency. The implementation inherited from the abstract implementation would already work.

    • compareTo

      public int compareTo​(java.util.List<? extends java.lang.Integer> l)
      Description copied from class: AbstractIntList
      Compares this list to another object. If the argument is a List, this method performs a lexicographical comparison; otherwise, it throws a ClassCastException.
      Specified by:
      compareTo in interface java.lang.Comparable<java.util.List<? extends java.lang.Integer>>
      Overrides:
      compareTo in class AbstractIntList
      Parameters:
      l - a list.
      Returns:
      if the argument is a List, a negative integer, zero, or a positive integer as this list is lexicographically less than, equal to, or greater than the argument.