new T

gistfile1.java

/**
 * We can't write 'new T()' in Java, and it wouldn't be typesafe if we could. Some people blame type erasure for this, but
 * the real problem is that we haven't specified that T has a zero-argument constructor, we just assumed it.
 * To do it properly, encode the constructors through generics. No runtime type information needed...
 */

    interface Constructor0<T> {
        T make();
    }

    class Example0<T, F extends Constructor0<T>> {
        private final T thing;

        public Example0(F factory) {
            this.thing = factory.make();
        }
    }

    interface Constructor1<T, A> {
        T make(A a);
    }
    
    class Example1<T, F extends Constructor1<T, Integer>> {
        private final T thing;
        
        public Example1(F factory) {
            this.thing = factory.make(12);
        }            
    }