通用方法调用混乱

Question

I have created a function

public <T> void someFunction(T object) {
    object.someMethod();
}

I have two classes which has same someMethod() function definition. I have to invoke the function by passing argument, the object of these two classes depends on the input provided.

Answer 1

Since T has no type bounds, the compiler can't know if that parameter would be replaced by a class that has a someMethod method.

You can add a type bound:

public <T extends HasSomeMethod> void someFunction(T object) {
    object.someMethod();
}

Where HasSomeMethod is an interface that contains the someMethod method, and the two classes that have someMethod implement that interface. (it will also work if HasSomeMethod is a super-class of your two classes, and it contains the someMethod method (either abstract or not).

EDIT :

An example of wrapping PreparedStatement :

public class MyStatement implements HasSomeMethod
{
    PreparedStatement stmt;

    public MyStatement (PreparedStatement stmt) {
         this.stmt = stmt;
    }

    public void someMethod ()
    {
        stmt.someMethod ();
    }
}

Now if you have a PreparedStatement instance, you can write :

PreparedStatement ps = ...
MyStatement my = new MyStatement(ps);

and pass my to your someFunction method.