public class StackUsingArray { int size = 5; int top = -1; int[] a = new int[size]; boolean isEmpty(){ return (top<0); } void push(int x){ if(top>=(size-1)){ System.out.println("Stack Overflow"); } else{ top += 1; a[top] = x; System.out.println(x + " pushed into stack"); } } int pop(){ if(top<0){ System.out.println("Stack Underflow"); return 0; } else{ int res = a[top]; top--; return res; } } int peek(){ if(top<0){ System.out.println("Stack Underflow"); return 0; } else{ return a[top]; } } public static void main(String[] args) { StackUsingArray s = new StackUsingArray(); s.push(20); s.push(40); System.out.println(s.pop() + " popped out from stack"); s.push(30); System.out.println("The top element is " + s.peek()); System.out.println("Is stack empty? " + s.isEmpty()); System.out.println(s.pop() + " popped out from stack"); System.out.println(s.pop() + " popped out from stack"); System.out.println("Is stack empty? " + s.isEmpty()); } }