CODEWITHSUNDEEP
javaarraysloopsbreak
Josh Waitere
Josh Waitere

Reputation: 51

How to break continue a nested for-loop inside a while-loop?

Can I use break on a nested for-loop to get back to outer while-loop and use continue from inside the for-loop to force the while-loop to keep going? I can not get the for-loop conditions into my while-loop conditions so the while-loop might stop if I cannot continue on a specifically meet situation.

while(...some conditions...){
    ...print stuff
    for(...some instances are arrays, condition loop array...){
        if(...index meets conditions...){
            ...print once, some arrays might meet condition on multiple index
            break; //to prevent multiple printings
        }
    continue; //i don't want to force another while iteration if(false)
    //or is this continue for(loop) anyway?
    }
continue; //is this not essentially a while(true) loop with no return?
}

The reason I can not get the for-loop conditions into the while conditions is because there are more if conditions between the two loops like if(array == null) and if-condition x == true getArray() needs to be called if array is not passed in. Most of the time condition y and z print from while-loop but sometimes condition x is met so I need the for-loop. It's after the printing of the for-loop if(index true)) I need the while-loop to go again that I'm stuck with? Sometime this might happen from while-loop conditions anyway but I can see that it wont always, further more if for-loop if(index false)) is meet I don't want to force the while loop as this could get costly in run time processing and could possibly result in an endless loop.

PS I am a junior programer, I'm not even sure it this is possible? or makes sense, sorry if its a stupid question

Upvotes: 2

Views: 9490

Answers (3)

Davide Lorenzo MARINO
Davide Lorenzo MARINO

Reputation: 26926

You can break with label.

Here is a complete example showing it:

https://docs.oracle.com/javase/tutorial/displayCode.html?code=https://docs.oracle.com/javase/tutorial/java/nutsandbolts/examples/BreakWithLabelDemo.java

Basically the code is similar to this:

:myLabel


for (...) {
    for(...) {
        ...
        break myLabel; // Exit from both for loops
    }
}

Upvotes: 2

m0skit0
m0skit0

Reputation: 25873

continue and break apply to the immediate current scope, so if you're inside the for, it will apply to the for.

You can store the comparison result on a boolean variable to check if you want to continue.

I'm not a big fan of break and continue, it hinders readability in my opinion. You can acheive the same behavior using a different code structuring.

Upvotes: 0

SomeJavaGuy
SomeJavaGuy

Reputation: 7347

you can name your loops like this: 

namedLoop: for(...) {
    // access your namedloop
    break namedLoop;
}

Upvotes: 9

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