Implement Queue using two Stacks in Java

Please go through the below program to understand the code.

package test.sachi.dsnalgos;

import java.util.NoSuchElementException;

import java.util.Stack;

/*

 Create two stacks : 's' and 'tmps' as in the program given below

For insert operation :

    if size of s = 0 then

        push value into s

    else

        push all popped elements from s to tmps

        push value into s

        push all popped elements from tmps to s

For remove operation :

    if size of s = 0 then

        throw 'underflow' exception

    else 

        return pop element from s

 */

public class QueueUsingTwoStacks {

Stack <Integer> s;

Stack <Integer> tmps;

public QueueUsingTwoStacks(){

s=new Stack<Integer>();

tmps=new Stack<Integer>();

}

public void insert(int data){

if(s.size()==0){

s.push(data);

}else{

int l=s.size();

for (int i = 0; i < l; i++){

tmps.push(s.pop());

}

s.push(data);

for (int i = 0; i < l; i++){

s.push(tmps.pop());

}

}

}

public int remove() throws Exception

    {

        if (s.size() == 0)

            throw new NoSuchElementException("Underflow Exception");            

        return s.pop();

    }    

public int peek() throws Exception

    {

        if (s.size() == 0)

            throw new NoSuchElementException("Underflow Exception");            

        return s.peek();

    }        

public boolean isEmpty()

    {

        return s.size() == 0 ;

    }    

public int getSize()

    {

        return s.size();

    }    

public void display()

    {

        System.out.print("\nQueue = ");

        int l = getSize();

        if (l == 0)

            System.out.print("Empty\n");

        else

        {

                        

            for (int i = l - 1; i >= 0; i--)

                System.out.print(s.get(i)+" ");                

            System.out.println();

        }

    }

}