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. Element is also returned. |
5 | int search(Object element) Searches for element in the stack. If found, its offset from the top of the stack is returned. Otherwise, -1 is returned. |
The following program illustrates several of the methods supported by this collection
import java.util.*; public class StackDemo { static void showpush(Stack st, int a) { st.push(new Integer(a)); System.out.println("push(" + a + ")"); System.out.println("stack: " + st); } static void showpop(Stack st) { System.out.print("pop -> "); Integer a = (Integer) st.pop(); System.out.println(a); System.out.println("stack: " + st); } public static void main(String args[]) { Stack st = new Stack(); System.out.println("stack: " + st); showpush(st, 42); showpush(st, 66); showpush(st, 99); showpop(st); showpop(st); showpop(st); try { showpop(st); } catch (EmptyStackException e) { System.out.println("empty stack"); } } }
This will produce the following result
stack: [ ] push(42) stack: [42] push(66) stack: [42, 66] push(99) stack: [42, 66, 99] pop -> 99 stack: [42, 66] pop -> 66 stack: [42] pop -> 42 stack: [ ] pop -> empty stack
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