Chapter 17
The java.util Package

Stack

Name

Stack

Synopsis

Class Name:

java.util.Stack

Superclass:

java.util.Vector

Immediate Subclasses:

None

Interfaces Implemented:

None

Availability:

JDK 1.0 or later

Stack represents a last-in-first-out (LIFO) object stack. The push() method places an object on the top of the stack, while the pop() method retrieves the top object from the stack. The peek() method returns the top object without removing it from the stack.

Class Summary

public class java.util.Stack extends java.util.Vector {
  // Instance Methods
  public boolean empty();
  public synchronized Object peek();
  public synchronized Object pop();
  public Object push(Object item);
  public synchronized int search(Object o);
}

Instance Methods

empty

public boolean empty()

Returns

true if there are no objects on the Stack; false otherwise.

Description

This method returns a boolean value that indicates whether or not the Stack is empty.

peek

public Object peek()

Returns

A reference to the object that is returned by the next call to pop().

Throws

EmptyStackException: If the stack is empty.

Description

This method returns a reference to the object on the top of this Stack without removing it.

pop

public Object pop()

Returns

The object on top of this Stack.

Throws

EmptyStackException: If the stack is empty.

Description

This method returns the object on top of this Stack.

push

public Object push(Object item)

Parameters

item: The object to be added to the top of the stack.

Returns

The object just pushed.

Description

This method places the object on the top of this Stack.

search

public synchronized int search(Object o)

Parameters

o: The object to be found.

Returns

The object's distance from the top of the stack or -1 if it cannot be found.

Description

This method is used to determine if an object is on this Stack.

Inherited Variables

Method	Inherited From	Method	Inherited From
`capacityIncrement`	`Vector`	`elementCount`	`Vector`
`elementData`	`Vector`

Inherited Methods

Method	Inherited From	Method	Inherited From
`addElement()`	`Vector`	`capacity()`	`Vector`
`clone()`	`Vector`	`contains(Object)`	`Vector`
`copyInto(Object[])`	`Vector`	`elementAt(int)`	`Vector`
`elements()`	`Vector`	`ensureCapacity(int)`	`Vector`
`equals()`	`Object`	`finalize()`	`Object`
`firstElement()`	`Vector`	`getClass()`	`Object`
`hashCode()`	`Object`	`indexOf(Object)`	`Vector`
`indexOf(Object, int)`	`Vector`	`insertElementAt(Object, int)`	`Vector`
`isEmpty()`	`Vector`	`lastElement()`	`Vector`
`lastIndexOf(Object)`	`Vector`	`lastIndexOf(Object, int)`	`Vector`
`notify()`	`Object`	`notifyAll()`	`Object`
`removeAllElements()`	`Vector`	`removeElement(Object)`	`Vector`
`removeElementAt(int)`	`Vector`	`setElementAt(Object, int)`	`Vector`
`setSize()`	`Vector`	`size()`	`Vector`
`toString()`	`Vector`	`trimToSize()`	`Vector`
`wait()`	`Object`	`wait(long)`	`Object`
`wait(long, int)`	`Object`