CODEWITHSUNDEEP
javafileio
Leander
Leander

Reputation: 1395

Java parse File-path with different working directory

I have a file which contain several paths, like . (relative) or /Users/...../ (absolut). I need to parse the paths that are relative to the directory of the file that contains the paths and not the working-directory and create correct File-instances. I can not change the working directory of the Java-Program, since this would alter the behaviour of other components and i also have to parse several files. I don't think public File(String parent, String child)does what i want, but i may be wrong. The documentation is quite confusing.

Example:

file xy located under /system/exampleProgram/config.config has the following content:
.
/Users/Name/file
./extensions

i want to resolve these to:
/system/exampleProgram/
/Users/Name/file
/system/exampleProgram/file/

Upvotes: 0

Views: 1416

Answers (2)

Nadia Cerezo
Nadia Cerezo

Reputation: 602

So, I am going to assume that you have access to the path of the file you opened (either via File.getAbsolutePath() if it was a File descriptor or via a regex or something)...

Then to translate your relative paths into absolute paths, you can create new File descriptions with your opened file, like so:

File f = new File(myOpenedFilePath);
File g = new File(f, "./extensions");
String absolutePath = g.getCanonicalPath();

When you create a file with a File object and a String, Java treats the String as a path relative to the File given as a first argument. getCanonicalPath will get rid of all the redundant . and .. and such.

Edit: as Leander explained in the comments, the best way to determine whether the path is relative or not (and thus whether it should be transformed or not) is to use file.isAbsolute().

Upvotes: 1

Benjamin Berman
Benjamin Berman

Reputation: 591

Sounds like you probably want something like


    File fileContainingPaths = new File(pathToFileContainingPaths);
    String directoryOfFileContainingPaths =
    fileContainingPaths.getCanonicalFile().getParent();
    BufferedReader r = new BufferedReader(new FileReader(fileContainingPaths));
    String path;
    while ((path = r.readLine()) != null) {
       if (path.startsWith(File.separator)) {
          System.out.println(path);
       } else {
          System.out.println(directoryOfFileContainingPaths + File.separator + path);
       }
    }       
    r.close();

Don't forget the getCanonicalFile(). (You might also consider using getAbsoluteFile()).

Upvotes: 0

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