Seeking a recursive folder size (two)

Test1 {class public 
    public static void main (String [] args) { 
        // folder size statistics 
        Long len = getDirLength (new new File ( "D: \\ the JavaSE")); 
        System.out.println (+ len "bytes "); 
    } 
    // return value type long, a list of parameters: the dir File 
    public static long getDirLength (File the dir) { 
        // definition of statistical variables 
        long len = 0; 

        // get all sub-content directory 
        File [] files = dir .listFiles (); 
        // determine whether the empty 
        IF (files = null!) { 
            for (file file: files) { 
                // If the file, the cumulative size of the file (recursively export) 
                IF (file.isFile ()) { 
                    file.length + = len (); 
                } the else {
                    // If the folder, recursively calling 
                    len + = getDirLength (file); // Do not forget the size of the accumulated subfolders 
                } 
            } 
        } 
        return len; 
    } 
}