我们可以在 Java 中使用 null 对象调用静态方法吗?如果是这样，如何? [英] Can we call a static method with a null object in Java? If so, how?

问题描述

既然静态方法可以直接从类中调用(即ClassName.methodName)，那为什么还需要用类的对象来调用静态方法呢?

Since static methods can be called directly from the class (i.e. ClassName.methodName), why it is required to call a static method with the object of the class?

如果有人知道，请举例说明.

If someone knows then, elaborate with example.

public static void methodA(){

}

推荐答案

以下代码包含一个示例，其中通过 null 引用调用静态方法.

The following code contains an example, in which a static method is called via a null reference.

public class Test {
    public static void main(String... args) {
        Test test = null;
        test.greeting(); // call with null reference
    }
    public static void greeting() {
        System.out.println("Hello World");
    }
}

因为Test::greeting 是一个静态方法，表达式test.greeting() 与Test.greeting() 相同.因此，在运行时不会抛出 NullPointerException.

Because Test::greeting is a static method, the expression test.greeting() is identical to Test.greeting(). For that reason, there is no NullPointerException thrown at runtime.

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