Contoh Program Stack

class Stack
{
    private int maxSize;
    private String[] stackArray;
    private int top;
    
    public Stack(int s)
    {
        maxSize = s;
        stackArray = new String[maxSize];
        top = -1;
    }
        
    public void push(String j)
    {
        stackArray[++top] = j;
    }
        
    public String pop()
    {
        return stackArray[top--];
    }
   
    public boolean isEmpty()
    {
        return (top == -1);
    }
        
    public boolean isFull()
    {
        return (top == maxSize-1);
    }
}

import javax.swing.JOptionPane;
class StackApp
{
    public static void main(String[]args)
    {
        System.out.print("***Program Stack NPM***\n");
        Stack stack_X = new Stack(100);
        String input = JOptionPane.showInputDialog("Masukan NPM Anda : ");
        for(int i=0; i<9; i++)
        {            
            String tumpukan = input.substring(i,(i+1));
            stack_X.push(tumpukan);
        }
        System.out.println("> Tumpukan Digit NPM <");
        System.out.println("======================");
        System.out.println("|\t-----\t     |");
        while (!stack_X.isEmpty() )
        {
            String value = stack_X.pop();
            System.out.println("|\t| "+value+" |\t     |");
            System.out.println("|\t-----\t     |");
        }
        System.out.println("======================");
    }
}