Question

How to solve this problem

public class DoubleTest {

    public static void main(String[] args) {
        double dbl = (Double) null;
        String str = Double.toString(dbl);
        System.out.println(str);

    }

} 

With Error:

Exception in thread "main" java.lang.NullPointerException
    at test.java.DoubleTest.main(DoubleTest.java:6)

Any idea please?

I am asking this because I have a method that return Double which I have to convert to String again.

If my method returns null, then this problem happens.

Answer 1

If you have a method returning null like this:

Double d = myMethod();

Then you can have Double to String conversion like this:

String str = "";

if (d != null)
   str = d.toString();