How do I break out of nested loops in Java?

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I've got a nested loop construct like this:

for (Type type : types) {
    for (Type t : types2) {
         if (some condition) {
             // Do something and break...
             break; // Breaks out of the inner loop
         }
    }
}

Now how can I break out of both loops? I've looked at similar questions, but none concerns Java specifically. I couldn't apply these solutions because most used gotos.

I don't want to put the inner loop in a different method.

I don't want to return the loops. When breaking I'm finished with the execution of the loop block.

36 Answers

Like other answerers, I'd definitely prefer to put the loops in a different method, at which point you can just return to stop iterating completely. This answer just shows how the requirements in the question can be met.

You can use break with a label for the outer loop. For example:

public class Test {
    public static void main(String[] args) {
        outerloop:
        for (int i=0; i < 5; i++) {
            for (int j=0; j < 5; j++) {
                if (i * j > 6) {
                    System.out.println("Breaking");
                    break outerloop;
                }
                System.out.println(i + " " + j);
            }
        }
        System.out.println("Done");
    }
}

This prints:

0 0
0 1
0 2
0 3
0 4
1 0
1 1
1 2
1 3
1 4
2 0
2 1
2 2
2 3
Breaking
Done

You can use a named block around the loops:

search: {
    for (Type type : types) {
        for (Type t : types2) {
            if (some condition) {
                // Do something and break...
                break search;
            }
        }
    }
}

You can use labels:

label1: 
for (int i = 0;;) {
    for (int g = 0;;) {
      break label1;
    }
}

Use a function:

public void doSomething(List<Type> types, List<Type> types2){
  for(Type t1 : types){
    for (Type t : types2) {
      if (some condition) {
         // Do something and return...
         return;
      }
    }
  }
}

You can use a temporary variable:

boolean outerBreak = false;
for (Type type : types) {
   if(outerBreak) break;
    for (Type t : types2) {
         if (some condition) {
             // Do something and break...
             outerBreak = true;
             break; // Breaks out of the inner loop
         }
    }
}

Depending on your function, you can also exit/return from the inner loop:

for (Type type : types) {
    for (Type t : types2) {
         if (some condition) {
             // Do something and break...
             return;
         }
    }
}

Using 'break' keyword alone is not the appropriate way when you need to exit from more than one loops. You can exit from immediate loop No matter with how many loops your statement is surrounded with. You can use 'break' with a label! Here I've used the label "abc" You can write your code as following, within any function in Java

This code shows how to exit from the most outer loop

 abc: 
    for (int i = 0; i < 10; i++) { 
        for (int j = 0; j < 10; j++) { 
           for (int k = 0; k < 10; k++) { 
              if (k == 1){
                 break abc;
              } 
        } 
    } 
}

Also you can use break statement to exit from any loop in a nested loop.

    for (int i = 0; i < 10; i++) { 
       abc:for (int j = 0; j < 10; j++) { 
           for (int k = 0; k < 10; k++) { 
              if (k == 1){
                 break abc;
              } 
        } 
    } 
}

The following code shows an example of exiting from the innermost loop. In other works,after executing the following code, you are at the outside of the loop of 'k' variables and still inside the loop of 'j' and 'i' variables.

    for (int i = 0; i < 10; i++) { 
        for (int j = 0; j < 10; j++) { 
           for (int k = 0; k < 10; k++) { 
              if (k == 1){
                 break;
              } 
        } 
    } 
}

Labeled break concept is used to break out nested loops in java, by using labeled break you can break nesting of loops at any position. Example 1:

loop1:
 for(int i= 0; i<6; i++){
    for(int j=0; j<5; j++){
          if(i==3)
            break loop1;
        }
    }

suppose there are 3 loops and you want to terminate the loop3: Example 2:

loop3: 
for(int i= 0; i<6; i++){
loop2:
  for(int k= 0; k<6; k++){
loop1:
    for(int j=0; j<5; j++){
          if(i==3)
            break loop3;
        }
    }
}

Demo

public static void main(String[] args) {
    outer:
    while (true) {
        while (true) {
            break outer;
        }
    }
}

It's fairly easy to use label, You can break the outer loop from inner loop using the label, Consider the example below,

public class Breaking{
    public static void main(String[] args) {
        outerscope:
        for (int i=0; i < 5; i++) {
            for (int j=0; j < 5; j++) {
                if (condition) {
                    break outerscope;
                }
            }
        }
    }
}

Another approach is to use the breaking variable/flag to keep track of required break. consider the following example.

public class Breaking{ 
    public static void main(String[] args) {
        boolean isBreaking = false;
        for (int i=0; i < 5; i++) {
            for (int j=0; j < 5; j++) {
                if (condition) {
                    isBreaking = true;
                    break;
                }
            }
            if(isBreaking){
                break;
            }
        }
    }
}

However, I prefer using the first approach.

Java does not have a goto feature like there is in C++. But still, goto is a reserved keyword in Java. They might implement it in the future. For your question, the answer is that there is something called label in Java to which you can apply a continue and break statement. Find the code below:

public static void main(String ...args) {
    outerLoop: for(int i=0;i<10;i++) {
    for(int j=10;j>0;j--) {
        System.out.println(i+" "+j);
        if(i==j) {
            System.out.println("Condition Fulfilled");
            break outerLoop;
        }
    }
    }
    System.out.println("Got out of the outer loop");
}

Below is an example where "break" statement pushes the cursor out of the for loop whenever the condition is met.

public class Practice3_FindDuplicateNumber {

    public static void main(String[] args) {
        Integer[] inp = { 2, 3, 4, 3, 3 };
        Integer[] aux_arr = new Integer[inp.length];
        boolean isduplicate = false;
        for (int i = 0; i < aux_arr.length; i++) {

            aux_arr[i] = -1;

        }
        outer: for (int i = 0; i < inp.length; i++) {
            if (aux_arr[inp[i]] == -200) {
                System.out.println("Duplicate Found at index: " + i + " Carrying value: " + inp[i]);
                isduplicate = true;
                break outer;
            } else {
                aux_arr[inp[i]] = -200;
            }
        }

        for (Integer integer : aux_arr) {
            System.out.println(integer);
        }

        if (isduplicate == false) {
            System.out.println("No Duplicates!!!!!");
        } else {
            System.out.println("Duplicates!!!!!");
        }
    }

}
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