returning null instead of int

**youngstorm** · November 19th, 2012, 01:56 PM

Hi,
I have the following code. The point is to test returns.

public class objects
{
    public static void main(String[]args)
    {
        int x = 0;
    }
 
    public int testZero(int x)
    {
        if (x == 0)
            {
                System.out.println(x);
                return ;
            }
        else
            {
                return x;
            }
    }
}

As is, I get a "missing return value" error from the compiler for the line "return ;", line 13. If I remove that statement, I get "missing return statement".
How should/could I handle this? If my method has a return type, MUST I return a value of that type? Is there a way not to do that?

Thank you,
Mike

**helloworld922** · November 19th, 2012, 02:13 PM

an int can never have a null value because it's a Java primitive. However, there are wrapper classes for primitives which can be null.

ex.:

// didn't test run this, hopefully it works
public Integer testZero(int x)
{
    if(x == 0)
    {
        return null;
    }
    else
    {
        return x;
    }
}

Every execution path must end in either a return value or throwing something (usually an exception). There are a few odd cases where a method doesn't terminate normally (for example, System.exit()), but these are rare.

Why not use booleans? These are meant to hold true/false values, ideal for answering yes/no type questions.

public boolean isZero(int x)
{
    if(x == 0)
    {
        return true;
    }
    else
    {
        return false;
    }
}

**andreas90** · November 19th, 2012, 02:15 PM

Hello Mike!

Originally Posted by youngstorm

How should/could I handle this? If my method has a return type, MUST I return a value of that type? Is there a way not to do that?

Yes, you are correct. You must return a value of that type. There is no way you can avoid that - as far as I know.
A common way to handle this situation is to have some "default" return values. For example, return 0 for default or -1 for an error. Then in your program you can check if these values are returned and handle them accordingly.

Hope this helps.

**youngstorm** · November 19th, 2012, 03:14 PM

Thanks to both of you for your help. This is the info I was looking for. Also, glad to know about the wrapper classes, that will do what I was hoping to do. Again, no special reason; I'm just playing and learning.

Thanks again guys.

--- Update ---

How do I mark this thread as solved?

**helloworld922** · November 19th, 2012, 03:37 PM

At the top, under Thread Tools > Mark this thread as solved

**youngstorm** · November 19th, 2012, 04:01 PM

Thanks again.

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