Is there a way in Java to determine if a path is valid without attempting to create a file?

Question

I need to determine if a user-supplied string is a valid file path (i.e., if createNewFile() will succeed or throw an Exception) but I don't want to bloat the file system with useless files, created just for validation purposes.

Is there a way to determine if the string I have is a valid file path without attempting to create the file?

I know the definition of "valid file path" varies depending on the OS, but I was wondering if there was any quick way of accepting C:/foo or /foo and rejecting banana.

A possible approach may be attempting to create the file and eventually deleting it if the creation succeeded, but I hope there is a more elegant way of achieving the same result.

Answer 1

Path class introduced in Java 7 adds new alternatives, like the following:

/**
 * <pre>
 * Checks if a string is a valid path.
 * Null safe.
 *  
 * Calling examples:
 *    isValidPath("c:/test");      //returns true
 *    isValidPath("c:/te:t");      //returns false
 *    isValidPath("c:/te?t");      //returns false
 *    isValidPath("c/te*t");       //returns false
 *    isValidPath("good.txt");     //returns true
 *    isValidPath("not|good.txt"); //returns false
 *    isValidPath("not:good.txt"); //returns false
 * </pre>
 */
public static boolean isValidPath(String path) {
    try {
        Paths.get(path);
    } catch (InvalidPathException | NullPointerException ex) {
        return false;
    }
    return true;
}

Edit:
Note Ferrybig's comment : "The only disallowed character in a file name on Linux is the NUL character, this does work under Linux."

Answer 2

This would check for the existance of the directory as well.

File file = new File("c:\\cygwin\\cygwin.bat");
if (!file.isDirectory())
   file = file.getParentFile();
if (file.exists()){
    ...
}

It seems like file.canWrite() does not give you a clear indication if you have permissions to write to the directory.