在Java中，什么是布尔＆QUOT;操作顺序及QUOT ;? [英] In Java, what are the boolean "order of operations"?

问题描述

让我们看一个物体猫的一个简单的例子。我想肯定了不空猫为橙色或灰色。

 如果（猫= NULL＆放大器;！＆安培; cat.getColor（）==橙色|| cat.getColor（）==灰色）{
//做东西
}
 

我相信并且是第一位的，然后是OR。我有点模糊的，所以这里是我的问题：

1. 有人能走我通过这句话，所以我敢肯定，我得到了什么情况？




2. 另外，如果我加括号会发生什么;这是否改变操作的顺序？




3. 请问我的操作顺序，可改变从语言到语言？

解决方案

Java教程有说明的运算符precedence 。平等的运营商将首先计算，那么＆放大器;＆安培; ，那么 || 。括号将任何事情之前进行评估，因此增加他们可以更改顺序。这通常是pretty多从语言到语言相同，但它总是一个好主意，仔细检查。

这是在行为上的微小变化，你不期望能引起你花了整整一天的调试，那么那么你肯定评价的顺序将是什么它是把括号的地方是个好主意。

Let's take a simple example of an object Cat. I want to be sure the "not null" cat is either orange or grey.

if(cat != null && cat.getColor() == "orange" || cat.getColor() == "grey") {
//do stuff
}

I believe AND comes first, then the OR. I'm kinda fuzzy though, so here are my questions:

1. Can someone walk me through this statement so I'm sure I get what happens?

2. Also, what happens if I add parentheses; does that change the order of operations?

3. Will my order of operations change from language to language?

解决方案

The Java Tutorials has a list illustrating operator precedence. The equality operators will be evaluated first, then &&, then ||. Parentheses will be evaluated before anything else, so adding them can change the order. This is usually pretty much the same from language to language, but it's always a good idea to double check.

It's the small variations in behavior that you're not expecting that can cause you to spend an entire day debugging, so it's a good idea to put the parentheses in place so you're sure what the order of evaluation will be.

这篇关于在Java中，什么是布尔＆QUOT;操作顺序及QUOT ;?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！