public class Parent {
    int x = 5;
    public void Info(){
        System.out.println("Ini class Parent");
    }
}

Buat class dengan nama Child
public class Child extends Parent {

    int x = 10;

    public void Info() {
        System.out.println("Ini class Child");
    }
}

Buat class dengan nama Tes
public class Tes {

    public static void main(String[] args) {
        Parent tes = new Child();
        System.out.println("Nilai x=" + tes.x);
        tes.Info();
    }
}