Class ArrayList<E>

java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractList<E>
java.util.ArrayList<E>
All Implemented Interfaces:
Iterable<E>, Collection<E>, List<E>, RandomAccess
public class ArrayList<E> extends AbstractList<E> implements List<E>, RandomAccess

ArrayList is an implementation of List, backed by an array. All optional operations adding, removing, and replacing are supported. The elements can be any objects.

Since

1.2

  • Field Summary

    Fields inherited from class AbstractList

    modCount

  • Constructor Summary

    Constructors
    Constructor
    Description
    ArrayList()
    Constructs a new instance of ArrayList with ten capacity.
    ArrayList(int capacity)
    Constructs a new instance of ArrayList with the specified capacity.
    ArrayList(Collection<? extends E> collection)
    Constructs a new instance of ArrayList containing the elements of the specified collection.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    add(int location, E object)
    Inserts the specified object into this ArrayList at the specified location.
    boolean
    add(E object)
    Adds the specified object at the end of this ArrayList.
    boolean
    addAll(int location, Collection<? extends E> collection)
    Inserts the objects in the specified collection at the specified location in this List.
    boolean
    addAll(Collection<? extends E> collection)
    Adds the objects in the specified collection to this ArrayList.
    void
    clear()
    Removes all elements from this ArrayList, leaving it empty.
    boolean
    contains(Object object)
    Searches this ArrayList for the specified object.
    void
    ensureCapacity(int minimumCapacity)
    Ensures that after this operation the ArrayList can hold the specified number of elements without further growing.
    E
    get(int location)
    Returns the element at the specified location in this list.
    int
    indexOf(Object object)
    Searches this list for the specified object and returns the index of the first occurrence.
    boolean
    isEmpty()
    Returns if this Collection contains no elements.
    int
    lastIndexOf(Object object)
    Searches this list for the specified object and returns the index of the last occurrence.
    E
    remove(int location)
    Removes the object at the specified location from this list.
    boolean
    remove(Object object)
    Removes one instance of the specified object from this Collection if one is contained (optional).
    protected void
    removeRange(int start, int end)
    Removes the objects in the specified range from the start to the end, but not including the end index.
    E
    set(int location, E object)
    Replaces the element at the specified location in this ArrayList with the specified object.
    int
    size()
    Returns the number of elements in this ArrayList.
    Object[]
    toArray()
    Returns a new array containing all elements contained in this ArrayList.
    <T> T[]
    toArray(T[] contents)
    Returns an array containing all elements contained in this ArrayList.
    void
    trimToSize()
    Sets the capacity of this ArrayList to be the same as the current size.

    Methods inherited from class AbstractList

    equals, hashCode, iterator, listIterator, listIterator, subList

    Methods inherited from class AbstractCollection

    containsAll, removeAll, retainAll, toString

    Methods inherited from class Object

    clone, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface List

    containsAll, equals, hashCode, iterator, listIterator, listIterator, removeAll, retainAll, subList

  • Constructor Details

    • ArrayList

      public ArrayList()
      Constructs a new instance of ArrayList with ten capacity.

    • ArrayList

      public ArrayList(int capacity)

      Constructs a new instance of ArrayList with the specified capacity.

      Parameters
      • capacity: the initial capacity of this ArrayList.

    • ArrayList

      public ArrayList(Collection<? extends E> collection)

      Constructs a new instance of ArrayList containing the elements of the specified collection. The initial size of the ArrayList will be 10% larger than the size of the specified collection.

      Parameters
      • collection: the collection of elements to add.

  • Method Details

    • add

      public void add(int location, E object)

      Inserts the specified object into this ArrayList at the specified location. The object is inserted before any previous element at the specified location. If the location is equal to the size of this ArrayList, the object is added at the end.

      Parameters

      • location: the index at which to insert the object.

      • object: the object to add.

      Throws
      • IndexOutOfBoundsException: when location size()
      Specified by:
      add in interface List<E>
      Overrides:
      add in class AbstractList<E>

    • add

      public boolean add(E object)

      Adds the specified object at the end of this ArrayList.

      Parameters
      • object: the object to add.
      Returns

      always true

      Specified by:
      add in interface Collection<E>
      Specified by:
      add in interface List<E>
      Overrides:
      add in class AbstractList<E>
      Returns:

      true if this Collection is modified, false otherwise.

      Throws

      • UnsupportedOperationException: if adding to this Collection is not supported.

      • ClassCastException: @throws ClassCastException if the class of the object is inappropriate for this collection.

      • IllegalArgumentException: if the object cannot be added to this Collection.

      • NullPointerException: if null elements cannot be added to the Collection.

    • addAll

      public boolean addAll(int location, Collection<? extends E> collection)

      Inserts the objects in the specified collection at the specified location in this List. The objects are added in the order they are returned from the collection's iterator.

      Parameters

      • location: the index at which to insert.

      • collection: the collection of objects.

      Returns
      Specified by:
      addAll in interface List<E>
      Overrides:
      addAll in class AbstractList<E>
      Returns:

      true if this ArrayList is modified, false otherwise.

      Throws
      • IndexOutOfBoundsException: when location size()

    • addAll

      public boolean addAll(Collection<? extends E> collection)

      Adds the objects in the specified collection to this ArrayList.

      Parameters
      • collection: the collection of objects.
      Returns
      Specified by:
      addAll in interface Collection<E>
      Specified by:
      addAll in interface List<E>
      Overrides:
      addAll in class AbstractCollection<E>
      Returns:
      true if this ArrayList is modified, false otherwise.

    • clear

      public void clear()

      Removes all elements from this ArrayList, leaving it empty.

      See also

      • #isEmpty

      • #size

      Specified by:
      clear in interface Collection<E>
      Specified by:
      clear in interface List<E>
      Overrides:
      clear in class AbstractList<E>

    • contains

      public boolean contains(Object object)

      Searches this ArrayList for the specified object.

      Parameters
      • object: the object to search for.
      Returns
      Specified by:
      contains in interface Collection<E>
      Specified by:
      contains in interface List<E>
      Overrides:
      contains in class AbstractCollection<E>
      Returns:
      true if object is an element of this ArrayList, false otherwise

    • ensureCapacity

      public void ensureCapacity(int minimumCapacity)

      Ensures that after this operation the ArrayList can hold the specified number of elements without further growing.

      Parameters
      • minimumCapacity: the minimum capacity asked for.

    • get

      public E get(int location)
      Description copied from class: AbstractList

      Returns the element at the specified location in this list.

      Parameters
      • location: the index of the element to return.
      Returns

      the element at the specified index.

      Throws
      • IndexOutOfBoundsException: if location = size()
      Specified by:
      get in interface List<E>
      Specified by:
      get in class AbstractList<E>

    • indexOf

      public int indexOf(Object object)
      Description copied from class: AbstractList

      Searches this list for the specified object and returns the index of the first occurrence.

      Parameters
      • object: the object to search for.
      Returns
      Specified by:
      indexOf in interface List<E>
      Overrides:
      indexOf in class AbstractList<E>
      Returns:
      the index of the first occurrence of the object, or -1 if it was not found.

    • isEmpty

      public boolean isEmpty()
      Description copied from class: AbstractCollection

      Returns if this Collection contains no elements. This implementation tests, whether size returns 0.

      Returns
      Specified by:
      isEmpty in interface Collection<E>
      Specified by:
      isEmpty in interface List<E>
      Overrides:
      isEmpty in class AbstractCollection<E>
      Returns:

      true if this Collection has no elements, false otherwise.

      See also
      • #size

    • lastIndexOf

      public int lastIndexOf(Object object)
      Description copied from class: AbstractList

      Searches this list for the specified object and returns the index of the last occurrence.

      Parameters
      • object: the object to search for.
      Returns
      Specified by:
      lastIndexOf in interface List<E>
      Overrides:
      lastIndexOf in class AbstractList<E>
      Returns:
      the index of the last occurrence of the object, or -1 if the object was not found.

    • remove

      public E remove(int location)

      Removes the object at the specified location from this list.

      Parameters
      • location: the index of the object to remove.
      Returns

      the removed object.

      Throws
      • IndexOutOfBoundsException: when location = size()
      Specified by:
      remove in interface List<E>
      Overrides:
      remove in class AbstractList<E>

    • remove

      public boolean remove(Object object)
      Description copied from class: AbstractCollection

      Removes one instance of the specified object from this Collection if one is contained (optional). This implementation iterates over this Collection and tests for each element e returned by the iterator, whether e is equal to the given object. If object != null then this test is performed using object.equals(e), otherwise using object == null. If an element equal to the given object is found, then the remove method is called on the iterator and true is returned, false otherwise. If the iterator does not support removing elements, an UnsupportedOperationException is thrown.

      Parameters
      • object: the object to remove.
      Returns
      Specified by:
      remove in interface Collection<E>
      Specified by:
      remove in interface List<E>
      Overrides:
      remove in class AbstractCollection<E>
      Returns:

      true if this Collection is modified, false otherwise.

      Throws

      • UnsupportedOperationException: if removing from this Collection is not supported.

      • ClassCastException: if the object passed is not of the correct type.

      • NullPointerException: @throws NullPointerException if object is null and this Collection doesn't support null elements.

    • removeRange

      protected void removeRange(int start, int end)

      Removes the objects in the specified range from the start to the end, but not including the end index.

      Parameters

      • start: the index at which to start removing.

      • end: the index one after the end of the range to remove.

      Throws
      • IndexOutOfBoundsException: when start end or end > size()
      Overrides:
      removeRange in class AbstractList<E>

    • set

      public E set(int location, E object)

      Replaces the element at the specified location in this ArrayList with the specified object.

      Parameters

      • location: the index at which to put the specified object.

      • object: the object to add.

      Returns

      the previous element at the index.

      Throws
      • IndexOutOfBoundsException: when location = size()
      Specified by:
      set in interface List<E>
      Overrides:
      set in class AbstractList<E>

    • size

      public int size()

      Returns the number of elements in this ArrayList.

      Returns

      the number of elements in this ArrayList.

      Specified by:
      size in interface Collection<E>
      Specified by:
      size in interface List<E>
      Specified by:
      size in class AbstractCollection<E>
      Returns:
      how many objects this Collection contains, or Integer.MAX_VALUE if there are more than Integer.MAX_VALUE elements in this Collection.

    • toArray

      public Object[] toArray()

      Returns a new array containing all elements contained in this ArrayList.

      Returns

      an array of the elements from this ArrayList

      Specified by:
      toArray in interface Collection<E>
      Specified by:
      toArray in interface List<E>
      Overrides:
      toArray in class AbstractList<E>

    • toArray

      public <T> T[] toArray(T[] contents)

      Returns an array containing all elements contained in this ArrayList. If the specified array is large enough to hold the elements, the specified array is used, otherwise an array of the same type is created. If the specified array is used and is larger than this ArrayList, the array element following the collection elements is set to null.

      Parameters
      • contents: the array.
      Returns

      an array of the elements from this ArrayList.

      Throws
      • ArrayStoreException: @throws ArrayStoreException when the type of an element in this ArrayList cannot be stored in the type of the specified array.
      Specified by:
      toArray in interface Collection<E>
      Specified by:
      toArray in interface List<E>
      Overrides:
      toArray in class AbstractList<E>

    • trimToSize

      public void trimToSize()

      Sets the capacity of this ArrayList to be the same as the current size.

      See also
      • #size