Relatively Simple Question

[thepsion5]

Hi guys,
I'm trying to write a java program that does, among other things, compare two arrays of booleans. The problem I run in to is that some of these boolean variables can be null (signifying yes, know, or unknown) but I'm not sure how to compare a variable to null. Using this code with IntelliJ gives me a syntax error:

else if(firstAttributes[x] == null || secondAttributes[x] == null)
{
    distance = distance + 0.5;
}

It tells me that operator '==' cannot be applied to 'boolean', 'null.'
I distinctly remember being able to deal with this situation in some way, but I can't remember how. Any ideas?

[Phaelax]

I don't think a boolean can ever be null.

[aniseed]

I don't think a boolean can ever be null.

You are right; boolean is a primitive and it cannot be null.

[thepsion5]

I think I found a workaround for my problem...I havn't tried this out, but i think this code should do:

try
{
  if(firstAttributes[x] != secondAttributes[x])
  {
    distance++;
  }
}
catch(NullPointerException e)
{
  distance = distance + 0.5;
}

I believe that this will do the trick, although I havn't tested it out...

[aniseed]

I think I found a workaround for my problem...

I would call it the correct way of coding, not a workaround, although I usually do not approve of handling NullPointerException within the code.

In your case, I don't see a possible situation where a NPE would occur.

[ftr]

Booleans are by default false, aren't they? As in, if you declare a boolean without initialising it true/false, its set to false? Or am I being a silly bunny?

[Phaelax]

You would have to initialize, otherwise you'd get a warning when you compile.

[destin]

Not in an array.

boolean[] myArray = new boolean[10]; // array of ten booleans initialized to false

Same goes for instance and class variables.

public class JavaClass {
	public static void main(String args[]) {
		System.out.println(new MyClass().getMyBoolean); // prints false
	}
}

class MyClass {
	private boolean myBoolean;
	
	public boolean getMyBoolean() { return myBoolean; }
}