public class Base {

private int i = 2;public void display() {    System.out.println(i);}public Base() {    display();}

} public class Derived extends Base {

private int i = 22;public void display() {    System.out.println(i);}public Derived() {    i = 222;}public static void main(String[] args) {    Derived d = new Derived();}

} 输出结果为0，子类与父类的变量都存在，父类构造方法，调用子类的display()方法