How to rename all files of a folder using Java?

Often, when transferring files from the camera folder to a workspace where we would like to analyze the pictures, it becomes difficult to deal with long file and type them out again and again when testing them through a code. Also, the number of files might be too large to manually rename each one of them. Hence, it becomes a necessity to automate the renaming process.

Examples:

Input : Read 50 files from the folder 
"C:\Users\Anannya Uberoi\Desktop\myfolder":
Snapshot 1 (12-05-2017 11-57).png
Snapshot 2 (12-05-2017 11-57).png
Snapshot 3 (12-05-2017 11-57).png
Snapshot 4 (12-05-2017 11-57).png   and so on.

Output :Renamed to
1.png
2.png
3.png
4.png   and so on.

// Java program to illustrate
// how to rename Multiple Files
// together using single program
import java.io.File;
import java.io.IOException;

public class rename
{
    public static void main(String[] argv) throws IOException
    {
        // Path of folder where files are located
        String folder_path =
               "C:\\Users\\Anannya Uberoi\\Desktop\\myfolder";

        // creating new folder
        File myfolder = new File(folder_path);

        File[] file_array = myfolder.listFiles();
        for (int i = 0; i < file_array.length; i++)
        {

            if (file_array[i].isFile())
            {

                File myfile = new File(folder_path +
                         "\\" + file_array[i].getName());
                String long_file_name = file_array[i].getName();
                String[] tokens = long_file_name.split("\\s");
                String new_file_name = tokens[1];
                System.out.println(long_file_name);
                System.out.print(new_file_name);

                // file name format: "Snapshot 11 (12-05-2017 11-57).png"
                // To Shorten it to "11.png", get the substring which
                // starts after the first space character in the long
                // _file_name.
                myfile.renameTo(new File(folder_path +
                             "\\" + new_file_name + ".png"));
            }
        }
    }
}

Output:

The files get renamed successfully.

Note: A double slash (\\) is required since one of the backslash (\) acts as an escape character and the other backslash (\) denotes directory change.