Android
java.util
public class

java.util.ArrayList<E>

java.lang.Object
java.util.AbstractCollection<E> Collection<E>
java.util.AbstractList<E> List<E>
java.util.ArrayList<E> Serializable Cloneable List<E> RandomAccess

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

Summary

Fields inherited from class java.util.AbstractList

Public Constructors

            ArrayList()
Constructs a new instance of ArrayList with zero 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 in the specified collection.

Public Methods

          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 ArrayList.
          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.
          Object  clone()
Returns a new ArrayList with the same elements, size and capacity as this ArrayList.
          boolean  contains(Object object)
Searches this ArrayList for the specified object.
          void  ensureCapacity(int minimumCapacity)
Ensures that this ArrayList can hold the specified number of elements without growing.
          get(int location)
Returns the element at the specified location in this ArrayList.
          int  indexOf(Object object)
Searches this ArrayList for the specified object and returns the index of the first occurrence.
          boolean  isEmpty()
Returns if this ArrayList has no elements, a size of zero.
          int  lastIndexOf(Object object)
Searches this ArrayList for the specified object and returns the index of the last occurrence.
          remove(int location)
Removes the object at the specified location from this ArrayList.
          boolean  remove(Object object)
Removes the first occurrence of the specified object from this Collection.
          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.
        <T>  T[]  toArray(T[] contents)
Returns an array containing all elements contained in this ArrayList.
          Object[]  toArray()
Returns a new array containing all elements contained in this ArrayList.
          void  trimToSize()
Sets the capacity of this ArrayList to be the same as the size.

Protected Methods

          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.
Methods inherited from class java.util.AbstractList
Methods inherited from class java.util.AbstractCollection
Methods inherited from class java.lang.Object
Methods inherited from interface java.lang.Iterable
Methods inherited from interface java.util.Collection
Methods inherited from interface java.util.List

Details

Public Constructors

public ArrayList()

Constructs a new instance of ArrayList with zero capacity.

public ArrayList(int capacity)

Constructs a new instance of ArrayList with the specified capacity.

Parameters

capacity the initial capacity of this ArrayList

public ArrayList(Collection<? extends E> collection)

Constructs a new instance of ArrayList containing the elements in the specified collection. The ArrayList will have an initial capacity which is 110% of the size of the collection. The order of the elements in this ArrayList is the order they are returned by the collection iterator.

Parameters

collection the collection of elements to add

Public Methods

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
object the object to add

Throws

IndexOutOfBoundsException when location < 0 || >= size()

public boolean add(E object)

Adds the specified object at the end of this ArrayList.

Parameters

object the object to add

Returns

  • true

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

Inserts the objects in the specified Collection at the specified location in this ArrayList. The objects are added in the order they are returned from the Collection iterator.

Parameters

location the index at which to insert
collection the Collection of objects

Returns

  • true if this ArrayList is modified, false otherwise

Throws

IndexOutOfBoundsException when location < 0 || > size()

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

Adds the objects in the specified Collection to this ArrayList.

Parameters

collection the Collection of objects

Returns

  • true if this ArrayList is modified, false otherwise

public void clear()

Removes all elements from this ArrayList, leaving it empty.

See Also

public Object clone()

Returns a new ArrayList with the same elements, size and capacity as this ArrayList.

Returns

  • a shallow copy of this ArrayList

See Also

public boolean contains(Object object)

Searches this ArrayList for the specified object.

Parameters

object the object to search for

Returns

  • true if object is an element of this ArrayList, false otherwise

public void ensureCapacity(int minimumCapacity)

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

Parameters

minimumCapacity the minimum number of elements that this ArrayList will hold before growing

public E get(int location)

Returns the element at the specified location in this ArrayList.

Parameters

location the index of the element to return

Returns

  • the element at the specified index

Throws

IndexOutOfBoundsException when location < 0 || >= size()

public int indexOf(Object object)

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

Parameters

object the object to search for

Returns

  • the index of the first occurrence of the object

public boolean isEmpty()

Returns if this ArrayList has no elements, a size of zero.

Returns

  • true if this ArrayList has no elements, false otherwise

See Also

public int lastIndexOf(Object object)

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

Parameters

object the object to search for

Returns

  • the index of the last occurrence of the object

public E remove(int location)

Removes the object at the specified location from this ArrayList.

Parameters

location the index of the object to remove

Returns

  • the removed object

Throws

IndexOutOfBoundsException when location < 0 || >= size()

public boolean remove(Object object)

Removes the first occurrence of the specified object from this Collection. This operation traverses over the collection, looking for the specified object. Once the object is found, the object will be removed from the collection using the iterator's remove method. This collection will throw an UnsupportedOperationException if the iterator returned does not implement remove method, and the specified object is in this collection.

Parameters

object the object to remove

Returns

  • true if this Collection is modified, false otherwise

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 < 0 || >= size()

public int size()

Returns the number of elements in this ArrayList.

Returns

  • the number of elements in this ArrayList

public 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 when the type of an element in this ArrayList cannot be stored in the type of the specified array

public Object[] toArray()

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

Returns

  • an array of the elements from this ArrayList

public void trimToSize()

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

See Also

Protected Methods

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 past the end of the range to remove

Throws

IndexOutOfBoundsException when start < 0, start > end or end > size()
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