Adding an infix between file name and extension using java 8

Question

In my code, I would like to transform a path of the form

/a/path/to/a/file/image.jpg

to

/a/path/to/a/file/image_resized.jpg

Currently, I am using the the following code which uses FilenameUtils from apache commons IO.

public Path resize(Path original) {
    String baseName = FilenameUtils.getBaseName(original.toString());
    String extension = FilenameUtils.getExtension(original.toString());
    return Paths.get(original.getParent().toString(), baseName + "_resized." + extension);
}

I was wondering if some of this code could be enhanced using java 8 features, specifically:

• is there a java-8 way for extracting the extension and basename, without using a dependency on Apache Commons IO (FilenameUtils), and without regex (I prefer dependency on apache commons IO over using a regex here)
• joining to Paths without toString() in Paths.get(existingPath.toString(), "path/to/append");

The second part of the question is answered in Combine paths in Java

Answer 1

You don't need a library for such a small and simple task IMO (and no java-8 does not add support for that); and I also can't tell why a regex is out of the question

    int where = input.lastIndexOf(".");

    String result = input.substring(0, where) + "_resized" + input.substring(where);
    System.out.println(result);

Answer 2

How about this? you can use Path#resolveSibling(String) to get the path relative to the original path. and use the Path#getFileName to get the filename in path.

thanks to @Holger point out that I can use the regex "(.*?)(\\.[^.]+)?$" instead.

public Path resize(Path original) {
    return original.resolveSibling(original.getFileName().toString()
            //               v--- baseName 
            .replaceFirst("(.*?)(\\.[^.]+)?$", "$1_resized$2"));
            //                      ^--- extension            
}

Output

//            v---for printing, I used the `String` here,actually is Paths.get(...)
resize("/a/b/image.jpg") =>  "/a/b/image_resized.jpg";

resize("/a/b/image.1.jpg") => "/a/b/image.1_resized.jpg";

resize("/a/b/image1") => "/a/b/image1_resized";

Answer 3

I'm sure that Java8 doesn't have anything to deal with this. Maybe you can checkout the Files API from Guava.Files.getFileExtension(fileName)

Answer 4

This problem can be solved by using simple string operations, you don't need libraries for stuff like this. One of the solution to this problem is -

class Solution {
    public static void main(String[] args) {
     String path = "/a/path/to/a/file/image.jpg";
     String[] temp = path.split("/");
     String[] tmp = temp[temp.length - 1].split("\\.");
     tmp[0] = tmp[0] + "-resized";
     String fullname = String.join(".", tmp);
     temp[temp.length - 1] = fullname;
     String newPath =  String.join("/", temp);
     System.out.print(newPath);

  }
}

Answer 5

So, I combine your answers into this one:

First, there seem to be no way of java build in way of extracting the file name extension in java (other stackoverflow question)

Then using the String.lastIndexOf() is a simple reliable manner to get the extension (Eugene). Finally using Path.resolveSibling() (holi-java) joins the new filename with the parent path.

resulting code:

public Path resize(Path original) {
    String fileName = original.getFileName().toString();
    int extIndex = fileName.lastIndexOf(".");
    String baseName = fileName.substring(0,extIndex);
    String extension = fileName.substring(extIndex);
    return original.resolveSibling(baseName+"_resized"+extension);
}