How to replace a plus character using Java's String.replaceAll method

Question

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

Answer 1

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.

I.e. this example:

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

Answer 2

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 3

when in doubt, let java do the work for you:

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

Answer 4

If you want a simple string find-and-replace (i.e. you don't need regex), it may be simpler to use the StringUtils from Apache Commons, which would allow you to write:

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