You can put the file path to argument and create a list with all the filepaths and not put it the list manually. Then use a for loop and a reader. Example for txt files:
public static void main(String[] args) throws IOException{
File[] files = new File(args[0].replace("\\", "\\\\")).listFiles(new FilenameFilter() { @Override public boolean accept(File dir, String name) { return name.endsWith(".txt"); } });
ArrayList filedir = new ArrayList();
String FILE_TEST = null;
for (i=0; i