Find all files and folders in JAVA of a given file path and work on it

This function takes a file path, then checks whether is it a folder or not. if it is a folder then finds all files under it. It also checks is the file hidden or not and the file format. Here i checked text (.txt) file.

private void findFileFromFolder(java.io.File file){
    if (file.isDirectory()){
        java.io.File subFile[] = file.listFiles();
       
        for (int i = 0; i < subFile.length; i++){
            if (subFile[i].isDirectory()){
                this.findFileFromFolder(subFile[i]);
            } else {
                if (!subFile[i].isHidden() && this.isExtension(subFile[i], "txt")) {
                   this.doFileProcess( );
                }//if
            }//else
        }//for
    } else {
       this.doFileProcess( );
    }
}

private void doFileProcess( ){
    /// todo: add your file code
}