'if' 语句末尾的分号 [英] Semicolon at end of 'if' statement

问题描述

今天找了半个小时的bug，发现可以在if语句后加分号代替代码，像这样:

if(a == b);//做东西

这基本上意味着无论 a 是否等于 b 都会完成这些事情，并且 if 语句没有任何意义.为什么Java不给我一个错误?在任何情况下这会有用吗?

解决方案

为什么会这样?

检查风格

Pmd

他们可以立即突出显示诸如此类的问题.

我建议将这两种解决方案结合起来.

Today, after half an hour of searching for a bug, I discovered that it is possible to put a semicolon after an if statement instead of code, like this:

if(a == b);
// Do stuff

Which basically means that the stuff will be done whether a equals b or not, and the if statement has no point whatsoever. Why doesn't Java give me an error? Is there any situation in which this would be useful?

解决方案

Why does it happen?

Java Language Specification says that:

The Empty Statement

An empty statement does nothing.

EmptyStatement:
    ;

Execution of an empty statement always completes normally

It essentially means that you want to execute empty statement if a==b

if(a == b);

What should you do:

There are two main solutions to this problem:

1. You can avoid problems with empty statement by using code formatter and surrounding stuff inside if with { and }. By doing this Your empty statement will be much more readable.

   if(a == b){
     ;
   }
   

2. You can also check tools used for static code analysis such as:

   • Findbugs
   • Checkstyle
   • Pmd

   They can instantly highlight problems such as this one.

I would recommend to combine both solutions.

这篇关于'if' 语句末尾的分号的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！