对象==空或空==对象? [英] object==null or null==object?

问题描述

我听某人说null == object 比object == null 检查

例如:

void m1(Object obj ) {
   if(null == obj)  // Is this better than object == null ? Why ?
       return ;
   // Else blah blah
}

是否有任何原因或这是另一个神话?感谢您的帮助.

Is there any reasons or this is another myth ? Thanks for help.

推荐答案

这可能是从 C 学到的一个习惯，为了避免这种类型的错字(单个 = 而不是双 ==):

This is probably a habit learned from C, to avoid this sort of typo (single = instead of a double ==):

if (object = null) {

将常量放在 == 左侧的约定在 Java 中并没有真正有用，因为 Java 要求 if 中的表达式计算为 boolean 值，因此除非常量是 boolean，否则无论采用哪种方式放置参数，都会出现编译错误.(如果它是一个布尔值，你不应该使用 == 反正...)

The convention of putting the constant on the left side of == isn't really useful in Java since Java requires that the expression in an if evaluate to a boolean value, so unless the constant is a boolean, you'd get a compilation error either way you put the arguments. (and if it is a boolean, you shouldn't be using == anyway...)

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