java - 从孙类调用父类构造函数，调用父类或祖父类构造函数？

Question

当使用二级子类的父类(super class)构造函数时，它会将参数传递给祖父构造函数还是直接父构造函数？

//top class
public First(type first){
  varFirst = first;
}

//child of First
public Second(type second){
  super(second); //calls First(second)
}

//child of Second
public Third(type third){
  super(third); //calls First(third) or Second(third)?
}

Answer 1

super 调用直接父级的构造函数。所以 Third 中的 super 调用将调用 Second 的构造函数，后者又调用 First 的.如果您在构造函数中添加一些 print 语句，您自己就很容易看到这一点:

public class First {
    public First(String first) {
        System.out.println("in first");
    }
}

public class Second extends First {
    public Second(String second) {
        super(second);
        System.out.println("in second");
    }
}

public class Third extends Second {
    public Third(String third) {
        super(third);
        System.out.println("in third");
    }

    public static void main(String[] args) {
        new Third("yay!");
    }
}

你得到的输出:

in first
in second
in third