Why is a null reference exception not thrown when I try to print the value of a static field value from an uninitialized instance of a class.
I expected a Null reference exception in the following code:
public class Check {
static int i=1;
public static void main(String []args)
{
Check ch = null;
System.out.print(ch.i);
}
}
Produces output as: 1.
In your snippet, i is static that means it may not need to be instantiated that means the default constructor need not be called as:
Check ch= new Check();
as i is static only a reference will suffice. Like you did,
Check ch = null;
So doing,
System.out.println(ch.i);
will print the value of i that is 1 from static context
Because i is a static variable, it does not matter whether its value is obtained from an object or from the class.
See the note here:
https://docs.oracle.com/javase/tutorial/java/javaOO/classvars.html
Given that i is static (it can be accessed through the class directly, no need to use an instance for it), in the code ch.i, the compiler checks for the type of the reference of ch (Check) and use it for accessing the variable i instead of using the class instance. This mean null (the instance) is not used at all (thus we don't get any exception).
That's it, the output of Check.i is 1.
