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

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.

From stackoverflow

• 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);
  

• 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:

  "\\+"
  

  Aaron Maenpaa : I have the bad habit of using '/'s when building the regex and then running .replace('/', '\\'), so that I don't have to type "\\\\" to match a literal backslash.

  gustafc : If you want to replace a fixed string, Pattern.quote(String) is a very nice friend.

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

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

  John Topley : That's a nice technique - thanks.

• 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");
  

  Gerhard Dinhof : thx for pointing to this. helped me remembering using this non-regex solution in simple cases.

  Vinze : isn't that equivalent to using mystr.replace("+", "plus") ? replace does not use regex (while replaceAll does).