Checking if all entries in a 2d Boolean array are true/false using a method in Java?

Question

I'm working on a project but I feel stumped on this particular section. I need to create a method that returns a boolean value true if all entries in a 2d array are false, and returns false when as little as 1 of those values is true. currently, my code inside the method resembles this:

int counter = 0;
  for (int i = 0; i < lightArray.length; i++){
     for(int j = 0; j <lightArray[0].length; i++) {
        if (lightArray[i][j] == false) {
           counter++;
           if (counter == lightArray.length * lightArray[0].length) {
              return true;
           }
        }
        else {
           return false;
        }
     }
  }

My initital thought was that i would use a 'counter' variable so that the if statement would only return true if there was a 'counter' for every value in lightArray. After testing, it doesn't seem to register when all values are set to false.

I also tried a version of the code where this section

if (lightArray[i][j] == false) {
           counter++;
           if (counter == lightArray.length * lightArray[0].length) {
              return true;

}

just read as this:

if (lightArray[i][j] == false) {
              return true;

with no 'counter' variable involved at all, but when that code is in place, the method returns true as soon as it hits a single false value.

Is there another way that I am just not thinking of that I can check every value in the 2D array before returning a boolean?

"the method returns true as soon as it hits a single false value." Have it do the opposite: return false as soon as it hits a single true value. If you go through the entire array without that happening, then you know that it contains only false values. — TNT
– TNT, Commented Dec 6, 2017 at 22:35
wow yeah thanks I should have seen that, and I appreciate the advice — Dev Dog
– Dev Dog, Commented Dec 6, 2017 at 23:07

tsolakp · Accepted Answer · 2017-12-06 22:41:04Z

1

Usually the logic like you have should be in this form:

loop{
    if (negative_condition) return false;            
}
return true;

Notice that return true is outside of the loop.

In your case you have nested loop which should looks like this:

loop{
    loop{
        if (negative_condition) return false;  
    }          
}
return true;

Looking at the above pseudo code, your Java code should look like this:

for (int i = 0; i < lightArray.length; i++){
    for(int j = 0; j <lightArray[0].length; j++) {
       if (lightArray[i][j] == true) return false;
    }
 }

 return true;

edited Dec 6, 2017 at 22:41

answered Dec 6, 2017 at 22:35

tsolakp

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