How to break out from nested loop?

Question

I have a method to compare two list of objects.

The objects are unique in both lists.

I doing it with 2 level nested for loops

I want to terminate the inner for loop's remaining cycles if two objects match correctly.

Is it possible to terminate the remaining iteration of a for loop in Java?!

Thanks

The Sample Code:

public class NestedForLoops {

  public static void main(String[] args) {
    String one = "abcdefgh";
    String two = "ijkhmnop";
    System.out.println(nestedForLoop(one, two));

  }

  public static String nestedForLoop(String one, String two)
  {
    String res = "";
    for(int i = 0; i < one.length(); i++)
    {
        for(int j = 0; j < two.length(); j++)
        {
            if(one.charAt(i) == two.charAt(j)){
                System.out.println(i + "   " + j);
                res += one.charAt(i);
                continue;
            }
        }
    }
    return res;
  }

}

@ thephpdeveloper: I got the answer. I thought break can be only used in if statmetns. I should have gave a try to it. Ok, now i doubt how continue can be useful. — user405398
– user405398, Commented Jan 2, 2011 at 15:07

dacwe · Accepted Answer · 2011-01-02 14:51:57Z

3

Break inner:

for (Object o1 : list1)
   for (Object o2 : list2)
        if (o1.equals(o2))
            break;

Break outer for loop:

outer: for (Object o1 : list1)
   for (Object o2 : list2)
        if (o1.equals(o2))
            break outer;

answered Jan 2, 2011 at 14:51

dacwe

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Comments

Femaref · Accepted Answer · 2011-01-02 14:52:21Z

1

use the break; statement in the inner loop. If you want to terminate the outer one as well, you'd have to give the outer one a label and use break label;.

answered Jan 2, 2011 at 14:52

Femaref

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Comments

efficiencyIsBliss · Accepted Answer · 2011-01-02 14:55:33Z

1

Yes it is. Just put an if statement that checks for a match of the two objects, and within the if, put a break statement. Here's the code sample:

while(coinditions for loop 1)
{
    // loop body
    while(conditions for loop 2)
    {
         //loop body

         if(object1.compareTo(object2)==0)
         {
              break;
         }
    }
}

answered Jan 2, 2011 at 14:55

efficiencyIsBliss

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Comments

Sebastiaan van den Broek · Accepted Answer · 2011-01-02 14:54:59Z

0

Labeling works (as already replied)

If the method does exactly that, check for equality, then you could also just return from the method when the objects match, looks like a small enough method to not make returning a bad practise. Personally I'd find that more readable than using labels.

answered Jan 2, 2011 at 14:54

Sebastiaan van den Broek

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Comments

Vladimir Ivanov · Accepted Answer · 2011-01-02 14:57:26Z

0

public boolean foundEqual(List<Object> list1, List<Object> list2) {
  if (list1 == null || list2 == null) {
    throw new NullPointerException("Lists can not be null");
  }

  for (Object o1 : list1)
   for (Object o2 : list2)
        if (o1.equals(o2)) {
            return true;
        }

  return false;
}

answered Jan 2, 2011 at 14:57

Vladimir Ivanov

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Comments

AbdullahC · Accepted Answer · 2011-01-02 15:00:29Z

0

Use a multi-level break:

outside:
for (...)
  for (...) 
    if (found) break outside;

Alternatively, creating a separate method and using return instead of break should be more readable, since return statements are far more common.

edited Jan 2, 2011 at 15:00

answered Jan 2, 2011 at 14:55

AbdullahC

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