Why does a null value appear in string output?

Question

When I execute the following code the output is \"nullHelloWorld\". How does Java treat null?

import java.util.*;
import java.lang.*;
import java.io.*;

/* N         


        

Answer 1

When you try to concat null through + operator, it is effectively replaced by a String containing "null".

A nice thing about this is, that this way you can avoid the NullPointerException, that you would otherwise get, if you explicitly called .toString() method on a null variable.