To find out if an element is on the stack: the search() method : Stack « Collections « Java Tutorial

1. Java Tutorial
2. Collections
3. Stack

public int search(Object element)

The element at the top of the stack is at position 1.

Position 2 is next, then 3, and so on.

If the requested object is not found on the stack, -1 is returned.

import java.util.Stack;

public class MainClass {
  public static void main (String args[]) {
    Stack s = new Stack();
    s.push("A");
    s.push("B");
    s.push("C");

    System.out.println("Next: " + s.peek());
    s.push("D");

    System.out.println(s.pop());
    s.push("E");
    s.push("F");

    int count = s.search("E");
    while (count != -1 && count > 1) {
      s.pop();
      count--;
    }
    System.out.println(s);
  }
}

Next: C
D
[A, B, C, E]