Java Compilation Error with Method overloading

Question

What would be the best way to achieve testCall2 below without doing explicit parsing (Sub1) in?

class Super {
}

class Sub1 extends Super {
}

class Sub2 extends Super {
}

public void testCall2(Super in) {
    testCall(in);        // <~~~ Compilation Error 

}

public void testCall(Sub1 sub) {

}

public void testCall(Sub2 sub) {

}

You'll first need to move those methods inside classes to get this to compile. In Java, methods can only exist inside classes. — Andrew Janke
– Andrew Janke, Commented Dec 2, 2014 at 2:48
Just one of them, depends on the instanceOf in. However, the point is I don't want to use instanceOf or any explicit casting. — Lewis Wong
– Lewis Wong, Commented Dec 2, 2014 at 2:51

Sotirios Delimanolis · Accepted Answer · 2014-12-02 02:53:16Z

2

You'd have to refactor and use polymorphism. Declare the testCall method in Super

class Super {
    public void testCall() {}
}

and implement it in the subclasses.

Then invoke it

public void testCall2(Super in) {
    in.testCall(); 
}

Otherwise you'll have to use a cast to transform the value's type to a type expected by either of the methods.

answered Dec 2, 2014 at 2:53

Sotirios Delimanolis

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Comments

Sindhoo Oad · Accepted Answer · 2014-12-02 03:30:55Z

0

Obviously it will give compile time error because you are creating methods out of class body. your all methods are out of class body..

class Super {
}

class Sub1 extends Super {
}

class Sub2 extends Super {
}// your all three classes are started and ended immediately

public void testCall2(Super in) {
    testCall(in);        // <~~~ Compilation Error 

}

public void testCall(Sub1 sub) {

}

public void testCall(Sub2 sub) {

}
//and all three methods are defined out of any  class body.

answered Dec 2, 2014 at 3:30

Sindhoo Oad

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