Java-N个被覆盖的抽象方法之一的强制继承

Question

Using Java 6, I have a situation where I want to force a child class to implement 1 of N overridden methods. Let me explain with an example:

public abstract class TestClass {

  public abstract String isValidInput(ObjectOne objectOne);

  public abstract String isValidInput(ObjectOne objectOne, ObjectTwo objectTwo);

  public abstract String isValidInput(ObjectOne objectOne, ObjectTwo objectTwo, ObjectThree objectThree);

  //Lots of other Code

}

The problem I'm facing is that I do not know exactly how many objects or types of objects that I'm going to have to validate. However, I do know that there is a limited number of possibilities. (I used 3 in the example above but in reality it will likely be 5.) What I want to do is force my child class to implement only one of the isValidInput(...) methods depending on the situation.

What is the cleanest way to solve this problem?

Thank you very much for you time!

Answer 1

The only existing option in java is ellipsis (...) for a variable amount of arguments of the same type.

For example:

public void doSomething(Object... arguments){
    // something
}

arguments is in that case a simple array. Other options are probably rethinking the architecture. Which would be in my opinion the best option.

Answer 2

Why not make it a composition of above answers with added generics ?

public interface Validator<T> {

    boolean validate(T... objects);
}

public class StringValidator implements Validator<String> {

    @Override
    public boolean validate(String... objects) {
        return false;
    }
}

Answer 3

I do not know exactly how many objects or types of objects

Then make all the objects you want to test, regardless of type, implement the same interface. For example:

public interface Testable {
    public boolean isValid();
}

Then you can just pass a list of Testable objects:

public abstract class TestClass {
    public abstract String isValidInput(List<Testable> list);
}