Doubt regarding a method call.

[chaitanya karthikk]

Hi all, I have a doubt regarding a method call. The following code is calling method which is having a String argument. Whereas I thought that which execution ambiguity will arise. Can anyone please explain this?

package examples;

public class AmbiguityMethodCall {
	public void method(Object obj) {
		System.out.println("Object method");
	}
	public void method(String str) {
		System.out.println("String method");
	}
	public static void main(String kk[]) {
		new AmbiguityMethodCall().method(null);
	}
}

Thank you all in advance, good day.

[John Jai]

While passing null, it gets associated with the argument with the child in the lowest hierarchy level... In this case String extends from Object...

A similar sample code... Note that when you uncomment the method with Child4 argument, that does not extend the Child3 class, the method call using null gives error.

class Parentt {	
}

class Child1 extends Parentt{	
}

class Child2 extends Child1 {	
}

class Child3 extends Child2{	
}

class Child4 extends Parentt {
	
}

public class AmbiguityMethodCalls {
	public void method(Parentt p) {
		System.out.println("Parentt method");
	}
	public void method(Child1 str) {
		System.out.println("Child1 method");
	}
	public void method(Child2 str) {
		System.out.println("Child2 method");
	}
	public void method(Child3 str) {
		System.out.println("Child3 method");
	}
//	public void method(Child4 str) {
//		System.out.println("String method");
//	}
	
	public static void main(String kk[]) {
		new AmbiguityMethodCalls().method(null);
	}
}

[chaitanya karthikk]

Thank you @John

[Campbell Ritchie]

If you are getting into difficulty about which overloaded method is called when you pass null, you have probably got too many overloaded methods.

[Campbell Ritchie]

Dennis Deems,
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