I want to call a method of an abstract class from abstract class called by inherit class.
Abstract class:
public abstract class Abstract {
protected void updateMotionY(float deltaTime) {
System.out.println("Abstrcat updateMotionY");
}
public void update(float deltaTime) {
this.updateMotionY(deltaTime);
}
}
Inherit class:
public class Obj extends Abstract {
@Override
protected void updateMotionY(float deltaTime) {
System.out.println("updateMotionY");
super.updateMotionY(deltaTime);
}
@Override
public void update(float deltaTime) {
super.update(deltaTime);
}
}
Main method class:
public static void main(String[] args) {
(new Obj()).update(10.0f);
}
Whenever I try to call new Obj().update() method in main class, it prints "updateMotionY" and "Abstrcat updateMotionY". I want to get only "Abstrcat updateMotionY".
Can anyone tell me how to resolve this problem?
(new Obj()).update(10.0f) calls Obj::update which calls Abstract::update which calls this.updateMotionY. Because this is an instance of Obj, this calls Obj::updateMotionY.
This prints "updateMotionY".
This then calls super.updateMotionY(deltaTime) which is Abstract::updateMotionY.
This prints "Abstrcat updateMotionY".
That's the end of the call hierarchy and everything unwinds.
Fundamentally your confusion seems to stem from the fact that this.updateMotionY(deltaTime); in the Abstract class resolves to updateMotionY in the Obj class. That's basically the whole point of polymorphism.
One thing you could do is to add a private method (so that it cant be overridden) which contains the actual implementation, and defer to it:
public abstract class Abstract {
private void motionY(float dt)
{
System.out.println("Abstrcat updateMotionY");
}
protected void updateMotionY(float deltaTime) {
motionY(deltaTime);
}
public void update(float deltaTime) {
motionY(deltaTime);
}
}
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