Here is a main function that pushes ints on the Stack and then pops them all off in two different ways, along with sample output. Notice that this is a stack of Objects, so it is necessary to put each int into and Integer wrapper class.

// StackMain: Use Java's library Stack class (legacy)
import java.util.*; // for the Stack class and the exception class
public class StackMain { 

   public static void main(String[] args) {
      // create two stacks of Objects
      Stack s = new Stack();
      Stack t = new Stack();
      // push ints onto the stacks.  Need wrappers for int.
      //  Can assign Integer to Object, but not int to Object
      for (int i = 0; i < 10; i++) {
         Object obj = new Integer(i*i); // wrapper for i*i value
         s.push(obj); t.push(obj);
      }

      // three ways to peek at top element
      // s.peek() is an object, so must let system convert
      //   with +"", or must do an explicit cast
      int i = (new Integer(s.peek() + "")).intValue();
      System.out.println("1st peek: " + i);
      int j = Integer.parseInt(s.peek() + "");
      System.out.println("2nd peek: " + j);
      int k = ((Integer)s.peek()).intValue();
      System.out.println("3rd peek: " + k);

      // pop and print the first stack, using empty()
      //   method to terminate loop
      while (!s.empty())
         System.out.print(s.pop() + " ");
      System.out.println("\nEnd of the first stack");

      // try to pop an empty stack (get error message)
      try {
         s.pop();
      } catch (EmptyStackException ese) {
         System.out.println("Tried to pop empty stack");
      }

      // pop and print 2nd stack, using EmptyStackException
      //   to terminate loop (not the preferred method)
      while (true) {
         try {
            System.out.print(t.pop() + " ");
         } catch (EmptyStackException ese) {
            break;
         }
      }
      System.out.println("\nTh-th-th-th-that's-all-folks");
   }
}

% java StackMain
1st peek: 81
2nd peek: 81
3rd peek: 81
81 64 49 36 25 16 9 4 1 0 
End of the first stack
Tried to pop empty stack
81 64 49 36 25 16 9 4 1 0 
Th-th-th-th-that's-all-folks