如何使用Java的String.replaceAll方法替换加号字符

Question

What's the correct regex for a plus character (+) as the first argument (ie the string to replace) to Java's replaceAll method in the String class? I can't get the syntax right.

Answer 1

You need to escape the + for the regular expression, using \\ .

However, Java uses a String parameter to construct regular expressions, which uses \\ for its own escape sequences. So you have to escape the \\ itself:

"\\+"

Answer 2

如果有疑问，让java为你做的工作：

myStr.replaceAll(Pattern.quote("+"), replaceStr);

Answer 3

You'll need to escape the + with a \\ and because \\ is itself a special character in Java strings you'll need to escape it with another \\.

So your regex string will be defined as "\\\\+" in Java code.

Ie this example:

String test = "ABCD+EFGH";
test = test.replaceAll("\\+", "-");
System.out.println(test);

Answer 4

Others have already stated the correct method of:

1. Escaping the + as \\\\+
2. Using the Pattern.quote method which escapes all the regex meta-characters.

Another method that you can use is to put the + in a character class. Many of the regex meta characters ( . , * , + among many others) are treated literally in the character class.

So you can also do:

orgStr.replaceAll("[+]",replaceStr);

Ideone Link

Answer 5

如果你想要一个简单的字符串查找和替换（即你不需要正则表达式），使用Apache Commons中的StringUtils可能会更简单，这可以让你写：

mystr = StringUtils.replace(mystr, "+", "plus");

Answer 6

假设您要替换-使用\\\\\\- ，请使用：

 text.replaceAll("-", "\\\\\\\\-");

Answer 7

String str="Hello+Hello";   
str=str.replaceAll("\\+","-");
System.out.println(str);

OR

String str="Hello+Hello";   
str=str.replace(Pattern.quote(str),"_");
System.out.println(str);

Answer 8

How about replacing multiple '+' with an undefined amount of repeats?

Example: test+test+test+1234

(+) or [+] seem to pick on a single literal character but on repeats.