44

I have been using Java for quite some time, yet my education in loops is somewhat lacking. I know how to create every loop that exists in java and break out of the loops as well. However, I've recently thought about this:

Say I have two nested loops. Could I break out of both loops using just one break statement?

Here is what I have so far.

int points = 0;
int goal = 100;
while (goal <= 100) {
    for (int i = 0; i < goal; i++) {
        if (points > 50) {
           break; // For loop ends, but the while loop does not
        }
        // I know I could put a 'break' statement here and end
        // the while loop, but I want to do it using just
        // one 'break' statement.
        points += i;
    }
}

Is there a way to achieve this?

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0

6 Answers 6

Reset to default
86

In Java you can use a label to specify which loop to break/continue:

mainLoop:
while (goal <= 100) {
   for (int i = 0; i < goal; i++) {
      if (points > 50) {
         break mainLoop;
      }
      points += i;
   }
}
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7 Comments

@Grzegorz I do miss the good old days that I could use goto without someone pointing my back;)
@ziyao as long as the code is clear about what happens (the destination is near the goto) it's fine and IMHO cleaner
xkcd.com/292, that said, PHP allows you to "break 2;" the Java version is more clean and maintainable IMHO.
Yeah, while I usually prefer encapsuling the inner loop in an extra function because that's usually clearer, using a goto is surely clearer than using an extra boolean variable and setting that.
I cant believe I hadn't known this! Thank you so much for the new lesson!
|
20

Yes, you can write break with label e.g.:

int points = 0;
int goal = 100;
someLabel:
while (goal <= 100) {
   for (int i = 0; i < goal; i++) {
      if (points > 50) {
         break someLabel;
      }
   points += i;
   }
}
// you are going here after break someLabel;
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Comments

6

There are many ways to skin this cat. Here's one:

int points = 0;
int goal = 100;
boolean finished = false;
while (goal <= 100 && !finished) {
   for (int i = 0; i < goal; i++) {
      if (points > 50) {
         finished = true;
         break;
      }
   points += i;
   }
}

Update: Wow, did not know about breaking with labels. That seems like a better solution.

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2 Comments

Thanks! I wish I could accept all the answers!
It's cool. Your answer does make sense though. :)
1

Elementary, dear Watson ...

int points = 0;
int goal = 100;

while (goal <= 100) {
  for (int i = 0; i < goal; i++) {
    if (points > 50) {
      goal++;
      break;
    }
  points += i;
  }
}

or

int points = 0;
int goalim = goal = 100;

while (goal <= goalim) {
  for (int i = 0; i < goal; i++) {
    if (points > 50) {
      goal = goalim + 1;
      break;
    }
  points += i;
  }
}
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Comments

0

You can reset the loop control variables.

int points = 0;
int goal = 100;
while (goal <= 100) {
   for (int i = 0; i < goal; i++) {
      if (points > 50) {
         i = goal = 101;
      }
   points += i;
   }
}
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Comments

0

You shouldn't use labels in objective language. You need to rewrite the for/while condition.

So your code should look like:

int points = 0;
int goal = 100;
while (goal <= 100 && points <= 50) {
    for (int i = 0; i < goal && points <= 50; i++) {
        points += i;
    }
}

// Now 'points' is 55
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3 Comments

This does not really answer the question. It is more a comment.
post was updated for a sample code
What do you mean by "objective language"? Objective-C?

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