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: 
You need to escape the slash

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

```
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", "+");

```