declare generic parents statement in aspectj - aop

Question

Is it possible to use generic types with declare parents such that a class defined with generics implements an interface with the same generic types
i.e declare parents: AClass<Generic1,Generic2> implements
AnInterface<Generic1,Generic2>
What I am saying is whether it is possible to pass the generic types of the child to parents

Answer 1

Kind of. Check this out:
Generic class:
package de.scrum_master.app;
public class KeyValuePair<K,V> {
private K key;
private V value;
KeyValuePair(K key, V value) {
this.key = key;
this.value = value;
}
public K getKey() { return key; }
public V getValue() { return value; }
#Override
public String toString() {
return "KeyValuePair [key=" + key + ", value=" + value + "]";
}
}
Generic interface:
package de.scrum_master.app;
public interface KeyValueComparator<K, V> {
boolean equalsKey(K otherKey);
boolean equalsValue(V otherValue);
}
Aspect with ITD:
The ITD (inter-type definition) makes sure that the class implements the interface and also gets method implementations for the interface at the same time.
package de.scrum_master.aspect;
import de.scrum_master.app.KeyValuePair;
import de.scrum_master.app.KeyValueComparator;
public aspect InterfaceIntroductionAspect {
declare parents : KeyValuePair implements KeyValueComparator;
public boolean KeyValuePair.equalsKey(K otherKey) {
return this.getKey().equals(otherKey);
}
public boolean KeyValuePair.equalsValue(V otherValue) {
return this.getValue().equals(otherValue);
}
}
Driver application:
Create two different types of class objects and try to cast them both to the introduced interface:
package de.scrum_master.app;
public class Application {
public static void main(String[] args) {
KeyValuePair<Integer, String> pair1 = new KeyValuePair<>(11, "eleven");
System.out.println(pair1);
KeyValueComparator<Integer, String> comparator1 = (KeyValueComparator<Integer, String>) pair1;
System.out.println("equalsKey = " + comparator1.equalsKey(12));
System.out.println("equalsValue = " + comparator1.equalsValue("eleven"));
KeyValuePair<String, Integer> pair2 = new KeyValuePair<>("twelve", 12);
System.out.println(pair2);
KeyValueComparator<String, Integer> comparator2 = (KeyValueComparator<String, Integer>) pair2;
System.out.println("equalsKey = " + comparator2.equalsKey("twelve"));
System.out.println("equalsValue = " + comparator2.equalsValue(11));
}
}
Output:
KeyValuePair [key=11, value=eleven]
equalsKey = false
equalsValue = true
KeyValuePair [key=twelve, value=12]
equalsKey = true
equalsValue = false