方法重载的Java编译错误

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) {

}

Answer 1

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.

Answer 2

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.