Java中的无参构造函数和默认构造函数的区别 [英] Difference between a no-arg constructor and a default constructor in Java

问题描述

实际上，我不明白无参arg构造函数和默认构造函数之间的区别。

Actually I can not understand that what is the difference between a no-arg constructor and a default constructor.

import javax.swing.*;

public class Test extends JFrame {
   public Test() {
     super();
     this.setSize(200,200);
     this.setVisible(true);
   }
   public static void main(Sting[] arg) {
       Test cFrame = new Test();
   }
}

在创建时调用此类的默认构造函数默认构造函数是一个无参考的对象，名为cFrame？

Does this invoke the default constructor of this class while creating Test object called cFrame?

推荐答案

args构造函数，Java编译器代表您插入;它包含默认调用 super（）; （不是 supper c $ c>），这是默认行为。如果您实现了任何构造函数，那么您不再接收默认构造函数。

The default constructor is a no-args constructor that the Java compiler inserts on your behalf; it contains a default call to super(); (not supper()) which is the default behavior. If you implement any constructor then you no longer receive a default constructor.

JLS-8.8.9。默认构造函数说明（部分）

如果类不包含构造函数声明，

If a class contains no constructor declarations, then a default constructor with no formal parameters and no throws clause is implicitly declared.

如果被声明的类是原始类Object，那么默认构造函数具有一个空体。否则，默认构造函数只是调用没有参数的超类构造函数。

If the class being declared is the primordial class Object, then the default constructor has an empty body. Otherwise, the default constructor simply invokes the superclass constructor with no arguments.

这篇关于Java中的无参构造函数和默认构造函数的区别的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！