在Java中的类的主体内实例化对象 [英] Instantiating object from inside the main of that class in Java

问题描述

我通过我的OOP类文档，我发现这个例子：

I was looking through my OOP class documentation and I found this example:

class Student {
    private String name;
    public int averageGrade;


    public Student(String n, int avg) {
        name = n;
        averageGrade = avg;
    }

    public static void main(String[] args) {
        Student s = new Student("John", 9);
    }
}

我觉得很困惑，主要是同一个类。这被认为是不好的做法吗？新创建的对象 s 有主方法吗？

谢谢！

推荐答案

这里没有什么错。这是完全正常的。 （不可否认，对于具有main方法的类来说，显然可以执行更有意义 - main $ c> Student 类不太有意义。）

There's nothing wrong at all with this. It's entirely normal. (Admittedly it would make more sense for a class with a main method to be something one could obviously execute - a main method in a Student class doesn't make as much sense.)

对象实际上没有方法 - classes 有方法，无需任何特定上下文调用的静态方法，以及在该类型（或子类）的特定对象上调用的实例方法。

Objects don't really have methods - classes have methods, either static methods which are called without any particular context, and instance methods which are called on a particular object of that type (or a subclass).

虽然您可以调用 s.main（...），但实际上只是解析为静态方法的调用 Student.main ;你不应该调用静态方法via这样的表达式，因为它很混乱。

While you could call s.main(...) that would actually just resolve to a call to the static method Student.main; you shouldn't call static methods "via" expressions like this, as it's confusing.

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