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Thread: what is this? Variable?

  1. #1
    Java kindergarten chronoz13's Avatar
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    Default what is this? Variable?

    public class BreakingLoop {
     
         public static void main(String[] args) {
     
             int count = 0;
             loop_one:
     
                 for (int k=5;k < 100;k++) {
     
                     for (int j=3; j < 100; j++) {
     
                         if (j % 2 == 0) {
     
                             break;
                         }
     
                         if (k == 67) {
     
                             break loop_one;
     
                         }
                         count ++;
                     }
                 }
     
             System.out.println(count);
         }
     }

    i was searching some mild exercises on the net and i saw this one.. and one part intrigues me.
    what is that
    loop_one:
    ? the only thing i can notice and i dont know if my assumption is right..is, does it refer to the loops? and how come?
    when i removed it.. my IDE gave me an error -
    undefined Label

    can anyone kindly give me some explanation about that.. i never encountered such one before
    thanks


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: what is this? Variable?

    It's called a label. It's an old relic from way back when where you could simply "jump" to another section of code and start executing from there (via the infamous goto keyword). In Java, labels function a little differently. Technically goto is a defined keyword, but it doesn't do anything (and I think actually gives you a compile error). However, you could break/continue to a label. What that allows you to do is break or continue up multiple blocks.

    label1:
    for(int i = 0; i < 5; ++i)
    {
        for(int j = 0; j < 5;++j)
        {
            break label1; // breaks out of both loops, not just the inner loop
        }
        System.out.println("this will never execute");
    }

  3. The Following User Says Thank You to helloworld922 For This Useful Post:

    chronoz13 (May 8th, 2011)

  4. #3
    Java kindergarten chronoz13's Avatar
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    Default Re: what is this? Variable?

    thanks for the clear answer

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