So I got my program to do exactly what I want it to do, but it does not match the format below. Can someone correct my format?

import java.util.*;

public class StackList{

private static final String Stack = null;

static Scanner scan = new Scanner(System.in);

static void showpush(Stack st, int a) {

st.push(new Integer(a));

System.out.println("push(" + a + ")");

System.out.println("stack: " + st);

}

static void showpop(Stack st) {

System.out.print("pop -> ");

Integer a = (Integer) st.pop();

System.out.println(a);

System.out.println("stack: " + st);

}

public static void main(String args[]) {

Stack st = new Stack();

System.out.println("stack: " + st);

try {

showpop(st);

}catch (EmptyStackException e) {

System.out.println("empty stack");

int num = 0;

int s=0;

// loop to for the print shape

while (Stack == null) {

Random generator = new Random();

int ran_dom;

ran_dom = generator.nextInt(20);

System.out.println("Menu: ");

System.out.println("1: add(x) " + " " + "2: del(x)");

System.out.println("3: exist(x)" + " " + "4: Goodbye ");

System.out.print("Please select an options: " );

s = scan.nextInt();

// Allow me to select one of the 3 shapes

switch (s)

{

case 1:

System.out.print("Enter a number: ");

num = scan.nextInt();

System.out.println("You Enter: " + num);

showpush(st, num);

break;

case 2:

System.out.print("Enter a number: ");

num = scan.nextInt();

if (st.contains(num))

{

st.remove(Integer.valueOf(num));

System.out.println(st);

}

else

{

System.out.println("Error:");

}

break;

case 3:

System.out.print("Enter a number: ");

num = scan.nextInt();

if (st.contains(num)) {

System.out.println("Number Exists");

} else {

System.out.println("Number do not Exists");

}

break;

// Allow me to end the program

default:

System.out.print("Goodbye");

// System.exit(0);

}

}}}}

For this assignment, you are to write a program which implements a Set data structure using a singly linked list implementation and a driver program that will test this implementation. The Set ADT is a linear collection of data that will support the following operations: add(x)-adds the integer x to the collection. The resulting collection should not contain any duplicate values 1. 2. delete(x)- deletes the integer x from the set. 3. exists(x) returns true if the integer x exists in the set and false otherwise. 4. toString() - returns a string representing the set as a space separated list. The time complexity of all operations should be O(N), where N is the size of the collection. Program Design Requirements 1. Your program should consist of 3 classes: LinkedNode, Set, and Test. 2. The Test class is the driver class for your program (should contain only the main method). Inside the main method, you should create a new Set object, then enter an infinite loop in which the user is prompted to enter one of 3 commands: add x del x exists x stands for an actual number (some integer). The add and delete operations should perform the necessary operation (inserting or deleting the given integer) and then display the contents of the set using the toString() method. The exists command should output true or false depending on whether x exists in the set. 3. The Set class should implement the Set ADT by adding the appropriate variables and methods. There should be 1 method for each of the required operations. 4. The LinkedNode class should contain an integer value and a pointer to the next LinkedNode. 5. Make sure to validate all inputs. This means re-prompting the user if he or she entered something invalid