使用null对象引用调用静态方法时会发生什么？ [英] What happens when a static method is invoked using a null object reference?

问题描述

public class CallingStaticMethod {
public static void method() {
    System.out.println("I am in method");
}
public static void main(String[] args) {
    CallingStaticMethod csm = null;
    csm.method();
   }
}

有人可以解释如何调用静态方法上面的代码？

Can someone explain how the static method is invoked in the above code?

推荐答案

它已经被编译器优化了，因为没有必要拥有类的实例。编译器基本上替换

It's been optimized away by the compiler, simply because having an instance of the class is not necessary. The compiler basically replaces

csm.method();

by

CallingStaticMethod.method();

一般来说这也是一个很好的做法。即使普通的IDE也会警告你通过实例访问静态方法，至少Eclipse会在这里做。

It's in general also a good practice to do so yourself. Even the average IDE would warn you about accessing static methods through an instance, at least Eclipse does here.

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