import java.util.*;
class MyChk{
	public  static String getStr(){
		return ""+new Random().nextInt();
	}
}
public class MyTest04 {
	public static void main(String[] args) {
		try{
			//chkObj object is null
			MyChk chkObj=null;
			System.out.println("\t"+chkObj);
			System.out.println("\t"+chkObj.getStr());
		}
		catch (Exception exception){
			System.out.println("Exception ###\t"+exception.toString());
		}
	}
}

here chk is initalized with null ,why the method call chkObj.getStr() is working
what is the difference between method invocation chkObj.getStr() as shown above and method invocation like MyChk .getStr()
Plz help

 

 

Because calling a static method doesn't check the value of the variable at all, but only checks its type.


There is no difference in how it behaves!

That's a good reason to avoid calls like "chk.getStr()". It looks as if the value of chk actually matters for the call, while in fact it doesn't matter at all. You should always call static methods using the class name: "MyChk.getStr()", then it's clear what the intention and behavior is.

 

 

For a Start !!

 

 

Thanks for your fast response
Is an invocation like chkObj.getStr()(chkObj is null and method getSt() is static ) has anything to do with run time polymorphism if so Kindly Explain

 

 

If the method is static there is no runtime polymorphism.

 

 

No.

It's specifically because static methods are NOT runtime polymorphic that x.foo() works even when x is null. For runtime polymorphic methods--which in Java are non-private, non-final, non-static methods--x has to be non-null. It has to point to an object so the runtime knows which class' implementation of that method to call.