overloaded methods

[JayaSiji Gopal]

class A {}
class B extends A {}
class C extends B {}
class D {
void m1(A a) {System.out.print("A");}
void m1(B b) {System.out.print("B");}
void m1(C c) {System.out.print("C");}
public static void main(String[] args) {
A c1 = new C(); B c2 = new C();
C c3 = new C(); D d1 = new D();
d1.m1(c1); d1.m1(c2); d1.m1(c3);
}}

What is the result of attempting to compile and run the program?

a. Prints: AAA
b. Prints: ABC
c. Prints: CCC
d. Compile-time error
e. Run-time error
f. None of the above

in this eg, we have three overloaded methods in class D.
My q: in case of overloaded methods, in same class or in subclasses, the method call invocation is based on the variable reference type and not the run time reference type of the object instance.

please correct me.

[Arnab karmakar]

Hi jayashree,

Please put ur question clearly.
Let me explain what I have understood from ur question.

The a supper class object can be used to reference a sub class object, but the reverse way is not possible. But that does not mean that if u refer a super class object to a subclass object then it would call the functios of superclass. Thats why there is nothing complicated here. The subclass methods are called cooly.

Arnab

[Vipin Das]

Hi,
You are right.
FYI: If there are overloaded methods with base class , subclass parameters. Always the method which contains more specific subclass will be called.

class A {}
class B extends A {}
class C extends B {}
class E extends C{};//newly added
class D {
void m1(A a) {System.out.print("A");}
void m1(B b) {System.out.print("B");}
void m1(C c) {System.out.print("C");}
public static void main(String[] args) {
E e = new E();
A c1 = new C(); A c2 = new B();
C c3 = new C(); D d1 = new D();
    d1.m1(c1); d1.m1(c2); d1.m1(c3);
d1.m1(e);//newly added
}
}
 

In the above example there is no method for the type E, so call d1.m1(e) will execute void m1(C c) {System.out.print("C");} rather than calling the other methods. If the method void m1(C c) {System.out.print("C");} is not present it will execute void m1(B b) {System.out.print("B");}
and so on.