how to jump from inner loop to outer loop

Question

Here is the structure of my program:

for(loop1){

  if(condition1)
  {
    for(loop2)
    {
       for(loop3)
       {
         if(condition1_3)
           {
            As condition1_3 is true continue with loop2's next iteration, 
            No need to execute loop3's remaining iteration  
           }
           else
           {
             As condition1_3 is false no need to execute remaining part of loop3 and
             loop 2 but continue with loop1's remaining part i.e. condition1_1
           }
        }
     }
  }
  if(condition1_1)
  {
  some code here
  }
}

I know I have to use continue and break statement but don't understand exactly how? Please tell me how to achieve this mechanism?

Its not great practice but you can use a named break. I'll just lookup the syntax — Richard Tingle, Jul 09 '14 at 12:48
This should give you what you need: [Breaking out of nested loops in Java](http://stackoverflow.com/questions/886955/breaking-out-of-nested-loops-in-java) — Richard Tingle, Jul 09 '14 at 12:48
Your logic doesn't make sense... it seems loop 3 can only ever have 1 iteration so it doesn't make sense to have a 3rd loop at all — musefan, Jul 09 '14 at 12:51
basically in any iteration of loop3, you go through a block that says `No need to execute loop3's remaining iteration`... — njzk2, Jul 09 '14 at 12:52
I know you don't wait for such clever comments, but I really recommend to try to avoid these structures. They will bite you once at 2a.m., when you are under pressure and tired try to solve a problem there. Try to get rid of the condition1 by whatever guardian is possible and to outsource loop3 into an own function with a speaking name. It will be smoothly readable with a single glance. (end of Sunday's Word ^^) — peter_the_oak, Jul 09 '14 at 12:55

score 2 · Answer 1 · answered Jul 09 '14 at 12:49

If I understand your question, you could use the labeled continue,

loop1: for (;;) {
  if (condition1) {
    loop2: for (;;) {
      loop3: for (;;) {
        if (condition1_3) {
          continue loop2;
        } else {
          continue loop1;
        }
      }
    }
  }
}

score 1 · Answer 2 · answered Jul 09 '14 at 12:54

You can do as follows:

for(loop1){

  if(condition1)
  {
    for(loop2)
    {
       boolean flag=false;
       for(loop3)
       {
         if(condition1_3)
           {
            break; 
           }
           else
           {
             flag=true;
             break;
           }
        }
        if(flag)
          break;
     }
  }
  if(condition1_1)
  {
  some code here
  }
}

Alexander Sagen · Answer 3 · 2014-07-09T13:37:12.867

0

To break out and not continue the loop3 use break; if (condition1_3) break; The break; statement only breaks out of the current loop i think, not the loop it is nested in.

Edit: Missread the question To break out of both loops you can make a boolean flag before both loops and at the end of both loops have an if (breakOut) break; This will solv the question

edited Jul 09 '14 at 13:37

answered Jul 09 '14 at 12:52

Alexander Sagen

127
1
12

So what about the part where OP is asking to break out of 2 loops? – musefan Jul 09 '14 at 12:56

score 0 · Answer 4 · answered Jul 09 '14 at 12:52

Do like the following -

for(loop1){
  boolean flag = false;

  if(condition1)
  {
    for(loop2)
    {
       if(flag == true)
         break;

       for(loop3)
       {
         if(condition1_3)
           {    
             break;
           }
           else
           {
              flag = true;
              break;
           }
        }
     }
  }
  if(condition1_1)
  {
  some code here
  }
}

vinayknl · Answer 5 · 2014-07-09T13:09:07.447

Have a exit flags which is set when you want to exit a particular loop and check in each respective loops whether to continue or exit.

boolean exitLoop2 = false;

for(loop1){

 if(condition1)
 {
    for(loop2)
    {
       for(loop3)
       {
         if(condition1_3)
         {
             //As condition1_3 is true continue with loop2's next iteration, 
             //No need to execute loop3's remaining iteration  
             break;
         }
         else
         {
            //As condition1_3 is false no need to execute remaining part of loop3 and
            //loop 2 but continue with loop1's remaining part i.e. condition1_1
            exitLoop2 = true;
            break;
          }

       }
       if(exitLoop2)
       {
           break;
       }
    }
 }
 if(condition1_1)
 {
    some code here
 }

}

SUhrmann · Answer 6 · 2014-07-09T13:03:40.583

0

An option would be to use variables - but you have to think about correct setting of values:

boolean runFor1 = true;
boolean runFor2 = true;
boolean runFor3 = true;
for(loop1 && runFor1)
{
    for(loop2 && runFor2)
    {
       for(loop3 && runFor3)
       {
           setRunForX here to skip/unskip loops
       }
     }
  }
}

edited Jul 09 '14 at 13:03

answered Jul 09 '14 at 12:53

SUhrmann

632
1
8
26

This won't allow for breaking out of loop 2 so as to avoid the rest of the code in loop 2 itteration, as appears to be the request – musefan Jul 09 '14 at 12:57

dormux · Answer 7 · 2014-07-09T16:54:23.107

I'm not really shure what do you mean exactly. For me it simply looks like you want to jump out of the loops if a specific condition is satisfied. So you can either can define a label for your loops and use the continue labelLoopX; statement or you can satisfy the exit condition of loop3 if condition1_3==true resp. the exit condition of loop3 and loop2 if condition1_3==false. e.g. if loop3 looks like for ( int i = 0; i < 10; i++ ) like this:

if(condition1_3){
     //do something important
     i=10; //sets i to 10 and condition i < 10 is unsatified
}
else{
     //do some other important stuff
     i=10; //satify loop3's exitcondition
     j=10; //satify loop2's exitcondition
}

how to jump from inner loop to outer loop

7 Answers7