How to sort a Stack using a temporary Stack?

How to sort a Stack using a temporary Stack?

Code:

? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 import java.util.Stack;   public class StackSort {       public static Stack<Integer> sortStack(Stack<Integer> input){                   Stack<Integer> tmpStack = new Stack<Integer>();         System.out.println("=============== debug logs ================");         while(!input.isEmpty()) {             int tmp = input.pop();             System.out.println("Element taken out: "+tmp);             while(!tmpStack.isEmpty() && tmpStack.peek() > tmp) {                 input.push(tmpStack.pop());             }             tmpStack.push(tmp);             System.out.println("input: "+input);             System.out.println("tmpStack: "+tmpStack);         }         System.out.println("=============== debug logs ended ================");         return tmpStack;     }           public static void main(String a[]){                   Stack<Integer> input = new Stack<Integer>();         input.add(34);         input.add(3);         input.add(31);         input.add(98);         input.add(92);         input.add(23);         System.out.println("input: "+input);         System.out.println("final sorted list: "+sortStack(input));     } }

Output:

input: [34, 3, 31, 98, 92, 23] =============== debug logs ================ Element taken out: 23 input: [34, 3, 31, 98, 92] tmpStack: [23] Element taken out: 92 input: [34, 3, 31, 98] tmpStack: [23, 92] Element taken out: 98 input: [34, 3, 31] tmpStack: [23, 92, 98] Element taken out: 31 input: [34, 3, 98, 92] tmpStack: [23, 31] Element taken out: 92 input: [34, 3, 98] tmpStack: [23, 31, 92] Element taken out: 98 input: [34, 3] tmpStack: [23, 31, 92, 98] Element taken out: 3 input: [34, 98, 92, 31, 23] tmpStack: [3] Element taken out: 23 input: [34, 98, 92, 31] tmpStack: [3, 23] Element taken out: 31 input: [34, 98, 92] tmpStack: [3, 23, 31] Element taken out: 92 input: [34, 98] tmpStack: [3, 23, 31, 92] Element taken out: 98 input: [34] tmpStack: [3, 23, 31, 92, 98] Element taken out: 34 input: [98, 92] tmpStack: [3, 23, 31, 34] Element taken out: 92 input: [98] tmpStack: [3, 23, 31, 34, 92] Element taken out: 98 input: [] tmpStack: [3, 23, 31, 34, 92, 98] =============== debug logs ended ================ final sorted list: [3, 23, 31, 34, 92, 98]