Java不适用于regex \\ s，表示：无效的转义序列

Question

I want to replace all whitespace characters in a string with a "+" and all "ß" with "ss"... it works well for "ß", but somehow eclipse won't let me use \\s for a whitespace.. I tried "\\t" instead, but it doesn't work either.. I get the following error:

Invalid escape sequence (valid ones are \\b \\t \\n \\f \\r \\" \\' \\ )

this is my code:

try {
    String temp1 = from.getText().toString();
    start_from  = temp1.replaceAll("ß", "ss");
    start_from  = start_from.replaceAll("\s", "+");
}

why doesn't it work? is it a problem with android, eclipse or what?

thanks in advance!

Answer 1

您需要逃脱斜线

start_from  = start_from.replaceAll("\\s", "+");

Answer 2

The problem is that \\ is an escape character in java as well as regex patterns. If you want to match the regex pattern \\n , say, and you'd go ahead and write

replaceAll("\n", "+");

The regex pattern would not end up being \\n : it would en up being an actual newline, since that's what "\\n" means in Java. If you want the pattern to contain a backslash, you'll need to make sure you escape that backslash, so that it is not treated as a special character within the string.

replaceAll("\\s", "+");

Answer 3

You can use the java.util.regex.Pattern class and use something like p = Pattern.compile("\\s"); in combination with p.matcher(start_from).replaceAll("+") . Alternatively, just escape your "\\s" metacharacter as "\\\\s".