How do I restart a switch loop in Java

Question

I'm new in programming. I was building a rock paper scissors game. I got this problem. How do i restart it if user gives invalid choice. I tried restart(); command but nothing happens.

 Scanner sc = new Scanner(System.in);
        System.out.println("Hey player enter your name");
        String name = sc.nextLine();
        name = name.toLowerCase();
        int human_score=0;
        int pc_score=0;
        System.out.println("How many rounds u want to play "+name);
        byte rounds = sc.nextByte();
        if (rounds>10){
            System.out.println("Please choose up to 10 rounds. Above is not allowed");
            System.out.println("Exiting the game");
            System.exit(0);
        }
        int i =1;
        while (i<=rounds) {
            Random rand = new Random();
            int pc = rand.nextInt(3);
            pc += 1;
//            System.out.println(pc);
            System.out.println("What u choose?");

            int human = sc.nextInt();
            switch (human) {
                case 1 -> System.out.println("You choose rock");
                case 2 -> System.out.println("You choose paper");
                case 3 -> System.out.println("You choose scissors");
                default -> {
                    System.out.println("Invalid Choice");

                }

            }
            switch (pc) {
                case 1 -> System.out.println("I choose rock");
                case 2 -> System.out.println("I choose paper");
                case 3 -> System.out.println("I choose scissors");
            }
            if (human == pc) {

                System.out.println("Its a draw");
            } else if (human == 1 && pc == 2) {
                System.out.println("You lost. Better luck next time");
                pc_score+=1;
            } else if (human == 1) {
                System.out.println("Congrats. You won.");
                human_score+=1;
            } else if (human == 2 && pc == 1) {
                System.out.println("Congrats. You won.");
                human_score+=1;
            } else if (human == 2) {
                System.out.println("You lost. Better luck next time");
                pc_score+=1;
            } else if (human == 3 && pc == 1) {
                System.out.println("You lost. Better luck next time");
                pc_score+=1;
            } else if (human == 3) {
                System.out.println("Congrats. You won.");
                human_score+=1;
            }
            i+=1;
        }
        if (human_score==pc_score){
            System.out.println("Its a draw. Wanna play again?");
        } else if(human_score>pc_score){
            System.out.println("Congrats you won. Wanna challenge again?");
        }else System.out.println("Skill issue. This code is fine");

        System.out.println("PC\t"+name+"\n"+pc_score+"\t"+human_score);

So, if someone enters a invalid choice I want it to restart the loop, like try again. I couldn't find any way to do that(I am new, so don't know about all methods). Can u help me

Answer 1

If you wish to just make the user choose again in case of an Invalid input, you can add continue in the default case. Or if you want to increase the round as well, then increment the value of i before adding the continue keyword.

        switch (human) {
            case 1 -> System.out.println("You choose rock");
            case 2 -> System.out.println("You choose paper");
            case 3 -> System.out.println("You choose scissors");
            default -> {
                System.out.println("Invalid Choice");
                continue;

            }

        }

or if you want to increase the round as well,

        switch (human) {
            case 1 -> System.out.println("You choose rock");
            case 2 -> System.out.println("You choose paper");
            case 3 -> System.out.println("You choose scissors");
            default -> {
                System.out.println("Invalid Choice");
                i += 1;
                continue;
            }

        }

Though this code requires a lot of improvement, you should try getting started with the basics and of Java or any language you are working with. Happy coding!