为什么不能将Java类声明为static？ [英] Why can't a Java class be declared as static?

问题描述

我想找到为什么类不能被创建为静态的？ Like：

I am trying to find why the class cant be created as a static? Like:

public static class Qwert{

    public static void main(String args[]){

        int x = 12;
        while(x<12){
            x--;
        }
        System.out.println(" the X value is : "+ x);
    }
}

推荐答案

Java， static 关键字通常将方法或字段标记为对于类的每个实例不存在一次，而是一次。一个类存在一次，所以实际上，所有类都是静态这样，所有对象都是类的实例。

In Java, the static keyword typically flags a method or field as existing not once per instance of a class, but once ever. A class exists once anyway so in effect, all classes are "static" in this way and all objects are instances of classes.

static 确实对 inner 类有一个含义，这是完全不同的：通常内部类实例可以访问它绑定的外部类实例的成员，但如果内部类 static ，它没有这样的引用，可以实例化没有外部类的实例。也许你看到那个地方，然后试图在一个顶级类中使用它，在那里没有意义。

static does have a meaning for inner classes, which is entirely different: Usually an inner class instance can access the members of an outer class instance that it's tied to, but if the inner class is static, it does not have such a reference and can be instantiated without an instance of the outer class. Maybe you saw that someplace, then tried to use it on a top-level class, where it isn't meaningful.

也许你在其他语言如C＃ ，它的语法是一个很可怕的很像Java的。

Or maybe you saw it in other languages like C#, whose syntax is an awful lot like Java's.

（有一次我不知道为什么外部类实例没有被垃圾回收 - 因为我在其他地方保持对其内部类实例的引用，内部类不是 static ，因此有一个对外部类实例的引用。因此，默认情况下，我现在做内部类 static 。

(One time I couldn't figure out why an outer class instance wasn't being garbage-collected -- it was because I was keeping a reference to one of its inner class instances elsewhere, and the inner class was not static and so had a reference to the outer class instance. So by default, I make inner classes static now.)

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