Randomly choose a response java

This program must randomly choose a response whenever the answer is correct. and will ask the same question again if the answer is wrong.

My code is something like this.

Scanner reader = new Scanner(System.in);

    
    int response = 0;
    int answer = 0;
    
    
    while (true) {
    int num1 = (int) (Math.random() * 10 +1); 
    int num2 = (int) (Math.random() * 10 + 1);
    
    
    if (num1 < num2) {
        int temp = num1;
        num1 = num2;
        num2 = temp;
    }
    
    System.out.println("What is " + num1 + " times " + num2 + "?");
    answer = reader.nextInt();

    switch(response) {
        case 0:
            if (answer != (num1 * num2)) {
                System.out.println("No. Please try again.");
                System.out.println("What is " + num1 + " times " + num2 + "?");
                answer = reader.nextInt();
            }
            if (answer == (num1 * num2)) {
            System.out.println("Very good.");
            }
        case 1:
            if (answer != (num1 * num2)) {
                System.out.println("No. Please try again.");
                System.out.println("What is " + num1 + " times " + num2 + "?");
                answer = reader.nextInt();
            }
            if (answer == (num1 * num2)) {
            System.out.println("Very good.");
            }

and the task was "Use random-number generation to choose a number from 1 to 4 that will be used to select one of the four appropriate responses to each correct or incorrect answer. Use a switch statement to issue the responses."

The problem in the code that I have tried is that it doesn't randomly choose a response on my switch case statement, any ideas?