Breaking out of a for loop in Java [closed]

问题

In my code I have a for loop that iterates through a method of code until it meets the for condition.

Is there anyway to break out of this for loop?

So if we look at the code below, what if we want to break out of this for loop when we get to "15"?

public class Test {

   public static void main(String args[]) {

      for(int x = 10; x < 20; x = x+1) {
         System.out.print("value of x : " + x );
         System.out.print("\n");
      }
   }
}

Outputs:

value of x : 10
value of x : 11
value of x : 12
value of x : 13
value of x : 14
value of x : 15
value of x : 16
value of x : 17
value of x : 18
value of x : 19

I've tried the following to no avail:

public class Test {

   public static void main(String args[]) {
      boolean breakLoop = false;
      while (!breakLoop) {
          for(int x = 10; x < 20; x = x+1) {
             System.out.print("value of x : " + x );
             System.out.print("\n");
          if (x = 15) {
              breakLoop = true;
          }
          }
      }
   }
}

And I've tried a loop:

public class Test {

   public static void main(String args[]) {
      breakLoop:
          for(int x = 10; x < 20; x = x+1) {
             System.out.print("value of x : " + x );
             System.out.print("\n");
             if (x = 15) {
                 break breakLoop;
             }
      }
   }
}

The only way I can achieve what I want to is by breaking out of a for loop, I cannot subsitute it for a while, do, if etc statement.

Edit:

This was provided only as an example, this isn't the code I'm trying to get it implemented into. I have now solved the problem by placing multiple IF statements after where each loop initilizes. Before it would onlu jump out of one part of the loop due to lack of breaks;

回答1:

break; is what you need to break out of any looping statement like for, while or do-while.

In your case, its going to be like this:-

for(int x = 10; x < 20; x++) {
         // The below condition can be present before or after your sysouts, depending on your needs.
         if(x == 15){
             break; // A unlabeled break is enough. You don't need a labeled break here.
         }
         System.out.print("value of x : " + x );
         System.out.print("\n");
}

回答2:

You can use:

for (int x = 0; x < 10; x++) {
  if (x == 5) { // If x is 5, then break it.
    break;
  }
}

回答3:

If for some reason you don't want to use the break instruction (if you think it will disrupt your reading flow next time you will read your programm, for example), you can try the following :

boolean test = true;
for (int i = 0; i < 1220 && test; i++) {
    System.out.println(i);
    if (i == 20) {
        test = false;
    }
 }

The second arg of a for loop is a boolean test. If the result of the test is true, the loop will stop. You can use more than just an simple math test if you like. Otherwise, a simple break will also do the trick, as others said :

for (int i = 0; i < 1220 ; i++) {
    System.out.println(i);
    if (i == 20) {
        break;
    }
 }

回答4:

How about

for (int k = 0; k < 10; k = k + 2) {
    if (k == 2) {
        break;
    }

    System.out.println(k);
}

The other way is a labelled loop

myloop:  for (int i=0; i < 5; i++) {

              for (int j=0; j < 5; j++) {

                if (i * j > 6) {
                  System.out.println("Breaking");
                  break myloop;
                }

                System.out.println(i + " " + j);
              }
          }

For an even better explanation you can check here

回答5:

public class Test {

public static void main(String args[]) {

  for(int x = 10; x < 20; x = x+1) {
     if(x==15)
         break;
     System.out.print("value of x : " + x );
     System.out.print("\n");
  }
}
}

来源：https://stackoverflow.com/questions/15275195/breaking-out-of-a-for-loop-in-java

标签

java

loops

for-loop

break