how the compiler chooses a method from overloaded methods?

[kevinn lee]

 class Q{
}
class A extends Q {
}
class B extends A {
}
class C extends B {
static void m(A x, A y) {
System.out.print("AA");
}
static void m(A x, B y) {
System.out.print("AB");
}
static void m(C x, A y) {
System.out.print("BA");
}
static void m(B x, B y) {
System.out.print("BB");
}
static void m(Q x, C y) {
System.out.print("AC");
}
public static void main(String[] args) {
C c = new C();
m(c, c);
}
}  

in occasions like this when there is no exact match how does the compile choose one method?
what does the compiler take in to account when saying that the call to method is "ambiguous"(is it the number of widening operations)?
thanks

[Seetharaman Venkatasamy]

this kind of question discussed here many time. search here

[Emanuele Ghe]

Kevinn please post here if you find the answer, anyway your code does not compile.

Thanks.

[kevinn lee]

I couldnt find.can some one help
thanks

[kevinn lee]

Emanuele Ghe wrote:Kevinn please post here if you find the answer, anyway your code does not compile.

Thanks.

yeah it doesnt compile.
thanks

[Seetharaman Venkatasamy]

http://www.coderanch.com/t/241415/Programmer-Certification-SCJP/certification/Overloaded-Method-Call#1124087

[Seetharaman Venkatasamy]

understand? I ask you one question

you will get compilation error[ambiguous eference to a method] at this statement * m(c, c); * . to remove error you have to modify this statement. how will you do that?

[kevinn lee]

Seetharaman Venkatasamy wrote:understand? I ask you one question

you will get compilation error[ambiguous eference to a method] at this statement * m(c, c); * . to remove error you have to modify this statement. how will you do that?

thanks a lot

 m(c,(A)c);   

compiles

[Prithvi Sehgal]

Hello,

Snippet taken from JLS and your code snippet where the ambiguity has appeared

   

class Point { int x, y; }
class ColoredPoint extends Point { int color; }

class Test {
	static void test(ColoredPoint p, Point q) {
		System.out.println("(ColoredPoint, Point)");
	}
	static void test(Point p, ColoredPoint q) {
		System.out.println("(Point, ColoredPoint)");
	}
	public static void main(String[] args) {
		ColoredPoint cp = new ColoredPoint();
		test(cp, cp);											// compile-time error
	}
}

//Your code snippet
static void m(A x, A y) {  
System.out.print("AA");  
}

static void m(C x, A y) {  
System.out.print("BA");  
} 

This is where the ambiguity is happening. That's why you have to change like this

   
m(c,(A)c);

Because compiler is unable to decide and such a situation is causing ambiguity.

Hope this helps,

[kevinn lee]

thanks prithvi

[Prithvi Sehgal]

Hello,

Mate you are always welcome. From this we are learning also.

Keep rocking,