Generics and the ArrayList Class - Java - page 708

Display 14.1 Some Methods in the Class ArrayList (part 2 of 4)

public ArrayList< Base_Type >()

Creates an empty ArrayList with the specified Base_Type and an initial capacity of 10 .

ARRAYLIKE METHODS

public Base_Type set( int index, Base_Type newElement)

Sets the element at the specified index to newElement . Returns the element previously at that posi-
tion, but the method is often used as if it were a void method. If you draw an analogy between the
ArrayList and an array a , this statement is analogous to setting a[index] to the value newElement .
The index must be a value greater than or equal to 0 and less than the current size of the ArrayList .
Throws an IndexOutOfBoundsException if the index is not in this range.

public Base_Type get( int index)

Returns the element at the specified index. This statement is analogous to returning a[index] for an
array a . The index must be a value greater than or equal to 0 and less than the current size of the
ArrayList . Throws IndexOutOfBoundsException if the index is not in this range.

METHODS TO ADD ELEMENTS

public boolean add( Base_Type newElement)

Adds the specified element to the end of the calling ArrayList and increases the ArrayList 's size by
one. The capacity of the ArrayList is increased if that is required. Returns true if the add was success-
ful. (The return type is boolean , but the method is typically used as if it were a void method.)

public void add( int index, Base_Type newElement)

Inserts newElement as an element in the calling ArrayList at the specified index. Each element in
the ArrayList with an index greater or equal to index is shifted upward to have an index that is one
greater than the value it had previously. The index must be a value greater than or equal to 0 and less
than or equal to the current size of the ArrayList . Throws IndexOutOfBoundsException if the index
is not in this range. Note that you can use this method to add an element after the last element. The
capacity of the ArrayList is increased if that is required.

METHODS TO REMOVE ELEMENTS

public Base_Type remove( int index)

Deletes and returns the element at the specified index. Each element in the ArrayList with an
index greater than index is decreased to have an index that is one less than the value it had previ-
ously. The index must be a value greater than or equal to 0 and less than the current size of the
ArrayList . Throws IndexOutOfBoundsException if the index is not in this range. Often used as if
it were a void method.

protected void removeRange( int fromIndex, int toIndex)

Deletes all the element with indices i such that fromIndex ≤ i < toIndex . Element with indices

greater than or equal to toIndex are decreased appropriately.