interfaces.java

public class Main3 {
    private static class Data1 {
        private int data = 5;

        public int getData() {
            return data;
        }
    }

    private static class Data2 {
        private int data = 10;

        public int acquireData() {
            return data;
        }
    }

    private interface DataInterface<T> {
        public int getData(T data);
    }

    private static class Manipulator<T> {

        private DataInterface<T> iface;
        private T data;

        public void setInterface(DataInterface<T> iface) {
            this.iface = iface;
        }

        public Manipulator(T data) {
            this.data = data;
        }

        public void manipulate() {
            System.out.println(iface.getData(data));
        }
    }

    public static void main(String[] args) {
        Data1 D1 = new Data1();
        Data2 D2 = new Data2();

        Manipulator<Data1> M1 = new Manipulator<>(D1);
        M1.setInterface((data) -> data.getData());

        Manipulator<Data2> M2 = new Manipulator<>(D2);
        M2.setInterface((data) -> data.acquireData());

        M1.manipulate();
        M2.manipulate();

        // DataInterface<Data1> if1 = (data) -> data.getData();
        // DataInterface<Data2> if2 = (data) -> data.acquireData();
        // System.out.println(if1.getData(D1));
        // System.out.println(if2.getData(D2));
    }
}