java 没有大括号的嵌套 if-else 行为
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Nested if-else behaviour without braces
提问by usr-local-ΕΨΗΕΛΩΝ
Consider the following unformatted nested if-elseJava code
考虑以下未格式化的嵌套if-elseJava 代码
if (condition 1)
if (condition 2)
action 1;
else
action 2;
My question is: according to the Java language specifications, to what if does the elsebranch apply?
我的问题是：根据 Java 语言规范，如果else分支适用于什么？
By hand-reformatting and adding braces, which of these two is correct?
通过手动重新格式化和添加大括号，这两个中哪一个是正确的？
Block 1:
第 1 块：
if (condition 1) {
if (condition 2) {
action 1;
} else
action 2;
}
}
Block 2:
第 2 块：
if (condition 1) {
if (condition 2) {
action 1;
}
}
else {
action 2;
}
回答by Vincent van der Weele
From the documentation:
从文档：
The Java programming language, like C and C++ and many programming languages before them, arbitrarily decrees that an else clause belongs to the innermost if to which it might possibly belong.
Java 编程语言与 C 和 C++ 以及它们之前的许多编程语言一样，任意规定 else 子句属于它可能所属的最内层 if。
回答by ThaBomb
Block 1 is correct, in if else situations with no brackets the else is linked to the nearest if
块 1 是正确的，在没有括号的 if else 情况下，else 链接到最近的 if
if (condition 1)
if (condition 2)
action 1;
else
action 2;
is the same as
是相同的
if (condition 1)
if (condition 2)
action 1;
else
action 2;
also brackets are for the sake of understanding level, and ease. In larger if else statements, having no brackets makes error very common
括号也是为了理解层次，方便。在较大的 if else 语句中，没有括号会使错误非常普遍
回答by James Montagne
You can try it and find that the elseapplies to the inner if:
您可以尝试一下，发现else适用于内部if：
This is a good reason not to write code like this. It's very hard to read and understand what is happening.
这是不编写这样的代码的一个很好的理由。很难阅读和理解正在发生的事情。
回答by Duracell De Monaco
Just my 2 cents for a better visual representation.
只需我的 2 美分即可获得更好的视觉表现。
Everything inside braces will be completely ignored.
大括号内的所有内容都将被完全忽略。
if (false) {
if (true)
System.out.println("1");
else
System.out.println("2");
}
