파일 반복 변경 접미사

package com.heima.test;

import java.io.File;
import java.util.Scanner;

public class Test16 {

    /**  * @param args */
    public static void main(String[] args) {
        File dir = getDir();
        renameToFile(dir);
    }
    public static void renameToFile(File dir) {
        File[] subFiles = dir.listFiles();
        for (File subFile : subFiles) {
            if(subFile.isDirectory()){
            renameToFile(subFile);
            } else if(subFile.isFile()){
                if(subFile.getName().endsWith(".txt")){
                    System.out.println(subFile.getPath().replaceAll("\\.txt", ".doc"));
                    File newfile = new File(subFile.getPath().replaceAll("\\.txt",".doc"));
                    subFile.renameTo(newfile);
                }
            }
        }
    }

    public static File getDir(){
            Scanner sc = new Scanner(System.in);
            System.out.println(" ：");
            while(true){
                String line = sc.nextLine();
                File dir = new File(line);
                if(!dir.exists()){
                    System.out.println(" ！ ");
                }else if(dir.isFile()){
                    System.out.println(" ！ ：");
                }else{
                    return dir;
                }
            }
        }
}