CODEWITHSUNDEEP
javagenerics
Khafaga
Khafaga

Reputation: 1547

Invoking a method within a generic type class

Suppose that we have 2 classes A,B:

class A extends SomeClass {
   public String getProp() {
      return "propA";
   }
}

class B extends SomeOtherClass{
   private String propB;

   public B setProp(String value) {
      propB = value;
      return this;
   }

   public String getProp() {
      return propB;
   }
}

and suppose that we have another class called X and this class X has a method someMethod that takes a reference to any of these classes ,is there a way that we can use generics in this method to call getProp() according to the object that has been passed?

Upvotes: 0

Views: 86

Answers (4)

Khafaga
Khafaga

Reputation: 1547

Well this can be considered an answer , but I don't like it..

public class X<T>{
public void someMethod(T t) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException{
    t.getClass().getMethod("getProp", null).invoke(t, null);
}
public static void main(String[] args) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
    X<A> weird = new X<>();
    A a = new A();
    weird.someMethod(a);
}

}

Upvotes: 0

Sujay
Sujay

Reputation: 6783

Generics is meant for type-safety at compile time and not for achieving polymorphism at run-time. So I don't think what you're asking is possible.

In your scenario, you should consider creating an interface. Something like this:

public interface PropInf{
  String getProp();
}

You would then have to implement this interface in both your classes. Using a reference variable of this interface, you can then achieve polymorphism.

Upvotes: 0

epsalon
epsalon

Reputation: 2294

Define an interface as follows:

interface StringPropProvider {
  String getProp();
}

then define your classes to implement that interface:

class A extends SomeClass implements StringPropProvider {
   public String getProp() {
    return "propA";
}

class B extends SomeOtherClass implements StringPropProvider {
  private String propB;

  public B setProp(String value) {
    propB = value;
    return this;
  }

  public String getProp() {
    return propB;
  }
}

Upvotes: 0

driis
driis

Reputation: 164341

Not using generics.

You can define a common interface for these classes that has the getProp() method. The method using it should then accept an instance of the interface, and can call the getProp() method on the interface, which will be implemented by the concrete class you pass in.

Upvotes: 2

Related Questions