groovy或java：如何将'\\'替换为'\\\\''C：\\ www \\ web-app \\ StudyReports \\ test.bat'

Question

My eventual goal is to have a string like

def newline = 'C:\\www\web-app\StudyReports\\test.bat'

but my old line only has one '\\' .

I tried different ways of using the following:

def newline = oldline.replaceAll(/\\/,'//')

but that did not compile.

Answer 1

If I were you, I would replace the backslashes with forward slashes:

def newline=oldline.replaceAll(/\\+/, '/')

Both Java and Windows will accept the forward slash as a file separator, and it's lot easier to work with.

Answer 2

To match a single backslash in Java or Groovy, you have to enter it 4 times, because both the compiler and the regex engine use the backslash as the escape character. So if you enter "\\\\\\\\" as a String in Java, the compiler generates the string containing the two characters \\\\ , which the regex engine interprets as a match for exactly one backslash \\ .

The replacement string must be escaped twice too, so you have to enter 8 backslashes as the replacement string.

Answer 3

In Java, you'd use the String.replace(CharSequence target, CharSequence replacement) , which is NOT regex-based.

You'd write something like:

String after = before.replace("\\", "\\\\");

This doubles up every \\ in before .

String path = "1\\2\\\\3\\4";
System.out.println(path);
path = path.replace("\\", "\\\\");
System.out.println(path);

The output of the above is ( as seen on ideone.com )

1\2\\3\4
1\\2\\\\3\\4