为什么当我说 new House("x") 时会调用超类构造函数 Building()？
发布于2022-06-24 17:02 阅读(240) 评论(0) 点赞(1) 收藏(4)
我有以下代码，但我不明白为什么当我运行它时它会在打印"b"之前打印"h hn x"。为什么"b"会打印出来，因为我在Building执行时根本没有调用超类House()。
class Building {
Building() {
System.out.print("b ");
}
Building(String name) {
this();
System.out.println("bn " + name);
}
}
public class House extends Building {
House() {
System.out.println("h ");
}
House(String name) {
this();
System.out.println("hn " + name);
}
public static void main(String[] args) {
new House("x ");
}
}
解决方案
In inheritance it is necessary to initialize all the fields present in super-class first, because those fields are get used in subclasses, for this before construction of your subclass super class constructor get called to initialize all the field present in your super class.
Super class constructor called when you construct subclass instance. In your code you are creating new House("x "); Instance of House.
It calls House parametrized constructor House(String name) at this time your super class implicit constructor get called.
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