在Switch语句的中间终止while循环

Question

I want to terminate my while loop when user press 2 for exit but I entered loop again if user press 2 it did not exit please help me about it thanks

int count = 1;

while(count <=3) {

  System.out.println(" Enter any option");
  System.out.println(" Enter 1 for addition");
  System.out.println(" Enter 2 for exit");

  Scanner input = new Scanner (System.in);

  int option = input.nextInt();
  if(option==2) {
    System.out.println("Thank you for using app");
  }
  else
    switch(option) {
      case 1 :
         System.out.println("welcome to addtion");
         int sum;
         System.out.println("Enter first number");
         int x = input.nextInt();
         System.out.println("Enter second number");
         int y = input.nextInt();
         sum=x+y;
         System.out.println(sum);
      break;
      case 2 : 
         System.out.println("do you want to exit ? ");
      break;

    }   
 }

Answer 1

Perhaps your loop's condition should be :

 while (option != 2)

Your current condition - while (count <=3) doesn't make much sense, since count is not updated inside the loop.

Answer 2

You could use a labeled break

input: while( count <=3) {
...
...
switch( option) {
...
case 2:
...
    break input; // break the outer while loop
...

But I think it's generally better to encapsulate the while loop in a method and 'return' in cases like that.

Answer 3

Your while loop condition is suspect but a one line change would suffice.

if(option==2) { 
    System.out.println("Thank you for using app");
    break;
}