如何在 Java 的 Switch 语句中使用字符串

Question

My input String wont appear when im running the code. First it said it was unusable when i had it inside my Main method. After i took it out of my Main method and placed it in the Public class and the unusable problem got away. But still it wont appear while running the code.

public class Number0to9 {    
  public static String input;

  public static void main(String[] args) {        
    tryagain: while (true) {
      System.out.print("Type a number between 0 and 9 : ");

      Scanner scan = new Scanner(System.in);          
      int x = scan.nextInt();
      int output = x;
      input = "You entered number: ";

      switch (x) {
        case 0:
          input += output;
          break tryagain;
        case 1:
          input += output;
          break tryagain;
        case 2:
          input += output;
          break tryagain;
        case 3: 
          input += output;
          break tryagain;
        case 4:
          input += output;
          break tryagain;
        case 5: 
          input += output;
          break tryagain;
        case 6: 
          input += output;
          break tryagain;
        case 7:
          input += output;
          break tryagain;
        case 8:
          input += output;
          break tryagain;
        case 9:
          input += output;
          break tryagain;
        default:
          System.out.println("Your number was bigger than 9");
          break;
      }   
    }        
  } 
} 

Answer 1

should be something like this ?

public static void main(String[] args) {
        boolean digitEntered = false;
        String input = "You enetred number : ";
        while (digitEntered == false) {
            System.out.print("Type a number between 0 and 9 : ");
            Scanner scan = new Scanner(System.in);
            int x = scan.nextInt();

            if (x >= 0 && x <= 9) {
                digitEntered = true;
                input += x;
            } else {
                System.out.println("Your number was bigger than 9 ");

            }
        }
        System.out.println(input);
    }

Answer 2

Java break statement to terminate the labeled loop. And your String input contains value in it. Try to access it after the while loop.

public class Number0to9 {

    public static String input;

    public static void main(String[] args) {

    tryagain : while (true) {
    System.out.print("Type a number between 0 and 9 : ");
    Scanner scan = new Scanner(System.in);
    int x = scan.nextInt();
    int output = x;
    input = "You enetred number : ";


    switch (x) {
        case 0:
            input += output;
                break tryagain;
        case 1:
            input += output;
                break tryagain;
        case 2:
            input += output;
                break tryagain;
        case 3: 
            input += output;
                break tryagain;
        case 4:
            input += output;
                break tryagain;
        case 5: 
            input += output;
                break tryagain;
        case 6: 
            input += output;
                break tryagain;
        case 7:
            input += output;
                break tryagain;
        case 8:
            input += output;
                break tryagain;
        case 9:
            input += output;
                break tryagain;
        default:
                System.out.println("Your number was bigger than 9 ");
            break;
    }   
    }
System.out.println(input);
} 
} 

Answer 3

input += output;

The above statement of code can be used for adding input and output only if both the variables are int (or any other arithmetic variable type).

If you want to concatenate input and output, first of all, output should be converted to String.

input = input + Integer.toString(output);

Make this change in each case.