java修改.jpg图片和mp3音频文件的扩展名

    import java.io.File;
    import java.util.Scanner;
    
    public class test2pro {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("please choose whether to modify or recover?");
        String choose = sc.nextLine();
        int flag = 0;
        if(choose.equals("modify")){
            flag =1;
    
        }else{
            flag = 0;
        }
        modifyExtension(System.getProperty("user.dir"),flag);
    
        System.out.println("done");
    }
    //when flag = 1, cha