哪个具有更好的性能：test！= null或null！= test

没有不同。

第二个原因仅仅是因为C / C ++程序员总是执行分配而不是比较。

例如

// no compiler complaint at all for C/C++// while in Java, this is illegal.if(a = 2) {}// this is illegal in C/C++// and thus become best practice, from C/C++ which is not applicable to Java at all.if(2 = a) {}

而java编译器会生成编译错误。

因此，由于可读性强，我个人更喜欢第一个，人们倾向于从左到右阅读，

if test is not equal to null

null is notequal to test