Develop Reference

How to replace '\' with '//' in java String

For Example:
My String is:
C:\Users\Junaid\Documents\lesson2\lesson2\touchingRectangles\package.bluej
But I want it to be like this:
C://Users//Junaid//Documents//lesson2//lesson2//touchingRectangles//package.bluej

You can achieve the expected result with the following code -
path = path.replace("\\", "//");
Here the backslash() needs to be escaped by a backslash, as it throws invalid sequence error.
But honestly you don't need double front slash(//) unless you're handling anything like an URL(https://). Sometimes the filepath requires double blackslash(//) for file or stream inputs; but not always.
I would suggest you to use File.Separator instead. E.g.
String filePath = "hello" + File.separator + "world"
this gives you -"hello\world"; that is far more enough for file path manipulations.
Hope this helped :)

Is their any way to eliminate two backward slash to one in Eclipse

I came to a scenario while using eclipse, in which if i use two back slash in below mention function.
"private Keywords(){
try{
OR=new Properties();
FileInputStream fs=new FileInputStream(System.getProperty("user.dir")+"**\\src\\com\\config\\OR.properties"**);
OR.load(fs);
"
this function works but if I use single slash it won't work . Is their way that i would be able to use single backward slash only while giving a source path..

Your question has nothing to do with Eclipse.
You need to escape back-slashes in Strings, as they are themselves an escape character.
What you can eventually use to somewhat "shorten" your code is the system property System.getProperty("file.separator"), then assign it to some constant and use that reference instead.
But that's close to cosmetics.

You can use the 2 backslashes as a single variable say,
String separator = "\\";
String file_path = "src"+separator +"com"+separator +"config"+separator +"OR.properties";
System.out.println("File Path is :: " + file_path);
Or as Mena Suggested, you can use:
String separator = System.getProperty("file.separator");

Get it straight with your String literals
http://docs.oracle.com/javase/specs/jls/se7/html/jls-3.html

Java regex for Windows file path

I'm trying to build a Java regex to search a .txt file for a Windows formatted file path, however, due to the file path containing literal backslashes, my regex is failing.
The .txt file contains the line:
C\Windows\SysWOW64\ntdll.dll
However, some of the filenames in the text file are formatted like this:
C\Windows\SysWOW64\ntdll.dll (some developer stuff here...)
So I'm unable to use String.equals
To match this line, I'm using the regex:
filename = "C\\Windows\\SysWOW64\\ntdll.dll"
read = BufferedReader.readLine();
if (Pattern.compile(Pattern.quote(filename), Pattern.CASE_INSENSITIVE).matcher(read).find()) {
I've tried escaping the literal backslashes, using the replace method, i.e:
filename.replace("\\", "\\\\");
However, this is failing to find, I'm guessing this is because I need to further escape the backslashes after the Pattern has been built, I'm thinking I might need to escape upto an additional four backslashes, i.e:
Pattern.replaceAll("\\\\", "\\\\\\\\");
However, each time I try, the pattern doesn't get matched. I'm certain it's a problem with the backslashes, but I'm not sure where to do the replacement, or if there's a better way of building the pattern.
I think the problem is further being compounded as the replaceAll method also uses a regex, with means the pattern will have it's own backslashes in there, to deal with the case insensitivity.
Any input or advice would be appreciated.
Thanks

Seems like you're attempting to to a direct comparison of String against another. For exact matches, you could do (
if (read.equalsIgnoreCase(filename)) {
of simply
if (read.startsWith(filename)) {

Try this :
While reading each line from the file, replace '\' by '\\'.
Then :
String lLine = "C\\Windows\\SysWOW64\\ntdll.dll";
Pattern lPattern = Pattern.compile("C\\\\Windows\\\\SysWOW64\\\\ntdll\\.dll");
Matcher lMatcher = lPattern.matcher(lLine);
if(lMatcher.find()) {
System.out.println(lMatcher.group());
}
lLine = "C\\Windows\\SysWOW64\\ntdll.dll (some developer stuff here...)";
lMatcher = lPattern.matcher(lLine);
if(lMatcher.find()) {
System.out.println(lMatcher.group());
}

The correct usage will be:
String filename = "C\\Windows\\SysWOW64\\ntdll.dll";
String file = filename.replace('\\', ' ');

Replace "\\" with "/" in Java

I am trying to replace '\\'with '/' in java(Android) and this does not seem to work!
String rawPath = filePath.replace("\\\\", "/");
What is wrong with this ? I have escaped "\" and tried escaping '/' but to no use. Nothing happens to the original string.
filePath = abc\\xyz(not after escaping two \\, the original string is with two \\)
rawPath = abc \ xyz
expected = abc/xyz
Whats the correct way of doing this? (Another Windows file to Android path conversion prob)

When using String.replace(String, String) the backslash doesn't need to be escaped twice (thats when using replaceAll - it deals with regex). So:
String rawPath = filePath.replace("\\", "/");
Or using char version:
String rawPath = filePath.replace('\\', '/');

You do not need the quad-druple escape,
\\\\
, just simply
\\
.

escape with single slash should be enough. Following is working fine for me.
String rawPath = filePath.replace("\\", "/");

public static void main(String[] args) {
String s = "foo\\\\bar";
System.out.println(s);
System.out.println(s.replace("\\\\", "/"));
}
will print
foo\\bar
foo/bar

If you want to replace a sequence of 2 backslashes in your original string with a single forward slash, this should work:
String filePath = "abc\\\\xyz";
String rawPath = filePath.replace("\\\\", "/");
System.out.println(filePath);
System.out.println(rawPath);
outputs:
abc\\xyz
abc/xyz

Do you really have two backslashes in the String in the first place? That only appears in Java source code. At runtime there will only be one backslash. So the task reduces to changing backslashes to forward slashes (why?). For which you need a regex if you are using replaceAll(), which would require four of them: two for the compiler, and two for the regex, but you aren't using that, you are using replace(), which isn't a regex, so you only need two, one for the compiler and one for itself.
Why are you doing this? It is never necessary to use a backslash in a File path in Java at all, and it is also never necessary to translate them to / unless you are doing URL-like things with them, in which case there are File.toURI() methods and URI and URL classes for that.

Here is a very small method to get the desktop path and show you how to replace them in the return statement.
public static String getDesktopPath() {
String desktopPath = System.getProperty("user.home") + "/Desktop";
return desktopPath.replace("\\", "/");
}

Java Regex - Changing path with an alias

I have a path called $SERVER/public_html/ab1/ab2/.
I want to change it so that instead of $SERVER it just replaces it with my user directory. So I do
path = path.replaceFirst("\\$SERVER", System.getProperty("user.dir"));
but when I run it, it removes my \ in the new string.
F:Programming ProjectsJava Project/public_html/ab1/ab2/

Pattern has a String quote(String) function that will help you for the first string and Matcher has String quoteReplacement(String) for the second:
path = path.replaceFirst(java.util.regex.Pattern.quote("$SERVER"), java.util.regex.Matcher.quoteReplacement(System.getProperty("user.dir")));
edit: the reason you have to escape anything is because the second string has the semantics of Matcher.appendReplacement which treats backslashes and dollars as escape next char and insert captured group resp.
from the doc:
Note that backslashes () and dollar
signs ($) in the replacement string
may cause the results to be different
than if it were being treated as a
literal replacement string. Dollar
signs may be treated as references to
captured subsequences as described
above, and backslashes are used to
escape literal characters in the
replacement string.
a more obvious solution is (be careful of the needed escaped with that backslash)
path = path.replaceFirst("\\$SERVER", System.getProperty("user.dir").replaceAll("\\\\","\\\\\\\\"));

Yea you are completly right. I am trying to figure out why it is happening so.
But at the moment the only think I can suggest is to go with such a solution.
public class RegExTest
{
public static void main(String[] args)
{
String path = "$SERVER/public_html/ab1/ab2";
System.out.println("path before="+path);
String user = System.getProperty("user.dir");
System.out.println("user="+user);
System.out.println("replaceFirst using user="+path.replaceFirst("\\$SERVER", user));
path = path.replaceFirst("\\$SERVER", "");
path = user +path;
System.out.println("path after="+path);
}
}
EDIT: ..Why it does that?
From what I see in the code of the method line 701 to 708 they must do it. They just skip them. As to the reason why they do it, I still am not sure.
EDIT2:
OK reading the doc for the method answers it all. They do it so they can interpret accordingly special characters. Thus when reading the replacement they spot a slash the algorithm assumes it can be a part of special character and in result skips it.
if (nextChar == '\\') {
cursor++;
nextChar = replacement.charAt(cursor);
result.append(nextChar);
cursor++;
} else if (nextChar == '$') {
// Skip past $
cursor++;

Ok so in Windows the default slashes look like so '\' whereas on *nix the slashes look like so '/' . The simplest way to get through this problem is to invoke the replace function with the following parameters '\\' and '/' . That way you path will have its slashes all facing the same way.