Contents
Introduction
The stack is a subclass of Vector that implements a standard last-in, first-out stack.
Stack only defines the default constructor, which creates an empty stack. The stack includes all the methods defined by Vector and adds several of its own.
Stack( )
Apart from the methods inherited from its parent class Vector, Stack defines the following methods −
| Sr.No. | Method & Description |
|---|---|
| 1 | boolean empty()
Tests if this stack is empty. Returns true if the stack is empty, and returns false if the stack contains elements. |
| 2 | Object peek( )
Returns the element on the top of the stack, but does not remove it. |
| 3 | Object pop( )
Returns the element on the top of the stack, removing it in the process. |
| 4 | Object push(Object element)
Pushes the element onto the stack. The element is also returned. |
| 5 | int search(Object element)
Searches for an element in the stack. If found, its offset from the top of the stack is returned. Otherwise, -1 is returned. |
Example:
import java.util.Stack;
public class StackDemo {
public static void main(String[] args) {
Stack<String> stack = new Stack();
stack.push("Andrew");
stack.push("Tracy");
stack.push("Kobe");
stack.push("James");
System.out.println(stack);
// Looks at the object at the top of this stack without removing it from the stack.
stack.peek();
//Removes the object at the top of this stack and returns that object as the value of this function.
stack.pop();
//Returns the 1-based position where an object is on this stack.
System.out.println(stack.search("Tracy"));
System.out.println(stack);
}
}
output
[Andrew, Tracy, Kobe, James] 2 [Andrew, Tracy, Kobe]