Suppose i have a project with many objects of different kinds, but they all have an instance variable X, how do i make a method that accepts an object of any type, and returns X?
Dummy code example:
class Car{
int X =19;
}
class Apple{
int X =21;
}
class Bee{
int X =32;
}
public int GetX(Object ANY_OBJECT_HERE){
return ANY_OBJECT_HERE.X;
}
You have 2 options.
Create an interface, say, Xholder, with one method, getX() that returns int. Have Car, Apple, and Bee implement Xholder by returning X. Then, your current GetX method is unnecessary; anything that would have called GetX(yourObject) would now call yourObject.getX().
Use reflection in GetX. Get the object's class with getClass() and get the class's Field with getField, passing the variable name "X". From there you can get the value.
The first option is the best, because reflection is slower and more error-prone.
Two ways off the top of my head:
That been said, your method interface is not correct: you do not expect ANY object, but only those who have that X property. That means that the first solution is, from a design perspective, the most correct.
Make all your Classes extends from a base abstract class (Say MyObject which contains X) and make GetX parameter type be MyObject.
Assuming you know that you could do this by using Polymorphism concepts with an interface or abstract method (of an abstract class);
You could resolve this issue by using Java Reflections. You can study more about it here
Why not just use the java.lang.Object as a Parameter?
getXmethod. Make all your classes implement that interface (possibly by returning the value of their field). Make yourGetXmethod accept a parameter of the interface type and invoke itsgetXmethod.getX