该java程序代码哪里错了啊？

Question

public class Base {

public static void main(String[] args) {
    Derive d = new Derive();

}
private int i;
public Base(int i) {
    this i = i;
}
class Derive extends Base{

    private int j;
}

}

Answer 1

1、Base有参构造器中应该是 this.i = i;
2、子类Derive应该写在Base类下边不是内部
3、由于创建Derive是用的无参构造器，所以需要重写Base和Derive的无参构造器方法
修改后代码如下：

public class Base {

    public static void main(String[] args) {
        Derive d = new Derive();
    }
    private int i;
    public Base() {
    }
    public Base(int i) {
        this.i = i;
    }

}
class Derive extends Base {
    private int j;
    public Derive() {
    }
}