Question

I have a method that takes a generic parameter type. The scenario I have is this method will be called with different parameter types.

class something{
    public void someMethod(){
        List<A> listA = ....; //Class A have a field String Id;
        List<B> listB = ....; //Class B haave a field String Id;

        testMethod(listA);
        testMethod(listB);
    }

    private <T> void testMethod( List<T> list ){
            for( T event : list ){
                //TODO (something like): event.getId();
            }
        }
}

In the above code all the parameters will be be a List<someObjectType>. All the object types have a common field and need to use the getter to fetch its value. Now since the method definition is generic, how do I achieve this?

Answer 1

Have A and B implement a common interface that has a method getID:

interface SomeInterface {
    String getID();
}

then you could have:

private <T extends SomeInterface> void testMethod(List<T> list) {
    for (T event : list) {
        // now you can use `event.getID()` here
    }
}