Is it possible to use generic Consumer as function argument in Java?

Question

Code:

public void ifChangedString(String key, Consumer<String> consumer) {
    ...
    consumer.accept(getString(key));
}

public void ifChangedBoolean(String key, Consumer<Boolean> consumer) {
    ...
    consumer.accept(getBoolean(key));
}

Is it possible to make single method like public <T> void ifChanged(String key, Class<T> clazz, Consumer<T> consumer)?

Well obvious solution is public void ifChanged(String key, Consumer<Object> consumer) but I don't want to use Object as argument type, better to use several methods like above.

The problem is that for accept method I need ? super XXX and only super is Object. So is it possible at all?

Answer 1

You can create generic method that accepts type T object and Consumer of type T

public <T> void ifChanged(T t, Consumer<T> consumer) {

    consumer.accept(t);

}

And you can call that method by passing any object with corresponding Consumer action

ifChanged("String", s->System.out.println(s.length()));
ifChanged(10, i->System.out.println(i.toString()));