Generics and the ArrayList Class - Java - page 709

Display 14.1 Some Methods in the Class ArrayList (part 3 of 4)

public boolean remove(Object theElement)

Removes one occurrence of theElement from the calling ArrayList . If theElement is found in the
ArrayList , then each element in the ArrayList with an index greater than the removed element's
index is decreased to have an index that is one less than the value it had previously. Returns true if
theElement was found (and removed). Returns false if theElement was not found in the calling
ArrayList .

public void clear()

Removes all elements from the calling ArrayList and sets the ArrayList 's size to zero.

SEARCH METHODS
public boolean contains(Object target)

Returns true if the calling ArrayList contains target ; otherwise, returns false . Uses the method
equals of the object target to test for equality with any element in the calling ArrayList .

public int indexOf(Object target)

Returns the index of the first element that is equal to target . Uses the method equals of the object
target to test for equality. Returns −1 if target is not found.

public int lastIndexOf(Object target)

Returns the index of the last element that is equal to target . Uses the method equals of the object
target to test for equality. Returns − 1 if target is not found.

MEMORY MANAGEMENT (SIZE AND CAPACITY)

public boolean isEmpty()

Returns true if the calling ArrayList is empty (that is, has size 0 ); otherwise, returns false .

public int size()

Returns the number of elements in the calling ArrayList .

public void ensureCapacity( int newCapacity)

Increases the capacity of the calling ArrayList , if necessary, in order to ensure that the ArrayList
can hold at least newCapacity elements. Using ensureCapacity can sometimes increase effi-
ciency, but its use is not needed for any other reason.

public void trimToSize()

Trims the capacity of the calling ArrayList to the ArrayList 's current size. This method is used to
save storage space.

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