英文:
Java: Purpose of double \\ characters?
问题
command = command.replaceAll("\\{player}", e.getPlayer().getName());
What is the purpose of the "\\" in "\\{player}" within that line?
Why doesn't the programmer just do "{player}"?
英文:
command = command.replaceAll("\\{player}", e.getPlayer().getName());
What is the purpose of the "\" in "\\{player}" within that line?
Why doesn't the programmer just do "{player}" ?
答案1
得分: 6
这是一个转义序列。因为在正则表达式中，{ 字符有特殊含义，所以需要进行转义，以表示你实际上是指字面的 {。
英文:
That's an escape sequence. Since the { character has a special meaning in a regex, it needs to be escaped to signify you actually meant the literal {.
答案2
得分: 2
反斜杠通常用于“转义”字符。通常可以用于正则表达式的字符。在这种情况下，{} 可以被解释为正则表达式（您可以用它进行字符串操作），因此您必须转义它们，以便您的 {} 被解释为文字括号，而不是正则表达式。
英文:
Backslash are usually to "escape" characters. Characters that usually can be used for regex. In this case, the {} can be interpreted as regex (which you can utilize for string manipulations), hence why you'd have to escape them for your {} to be interpreted as a literal brackets instead of reg ex.
答案3
得分: 1
\后面的一些字符具有特殊含义。
例如，\n 换行 \t 输入"tab"字符，诸如此类。
因此，如果您确实想在代码中写入\，比如 "c:\someFolder\someFile"，您应该使用 "C:\\someFolder\\someFile" </br>
\ 被称为转义字符
如果您写成
String text = "firstname\lastname";
编译器会给出"非法转义字符"的错误
这意味着您不应该单独使用""在您的代码中。
祝编码愉快！
英文:
"\ with some other characters have special meanings.
For example, \n moves to next line \t writes "tab" character and so on.
Because of this, if you really want to write \ in your code like, "c:\someFolder\someFile" you should use "C:\\someFolder\\someFile" </br>
\ called escape character
If you write
String text ="firstname\lastname";
compiler gives you an error "illegal escape character"
It means that you should not use"" alone in your code.
Happy coding!
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