public class FileSame {
    public static void main(String[] args) {
        String path="E:\\jar1";
        File file = new File(path);
        String[] strings = file.list();
        String[] strings3=new String[strings.length];
        char[] cs =null;
        for (int i = 0; i < strings.length; ++i) {
            cs = strings[i].toCharArray();
            for (int j = cs.length-1; j >=0; --j) {
                    if (cs[j]=='5') {
                        cs[j]='6';
                        break;
                    }
            }
            strings3[i]=new String(cs);     
        }
        String path2="E:\\jar2";
        File file2 = new File(path2);
        String[] strings2 = file2.list();
        Arrays.sort(strings);
        Arrays.sort(strings2);
        Arrays.sort(strings3);
        if (Arrays.equals(strings3, strings2)) {
            for (int i = 0,j=0; i < strings.length&&j<strings2.length; ++i,++j) {
                file=new File(path+File.separator+ strings[i]);
                file2=new File(path+File.separator+ strings2[j]);
                System.out.println(file.renameTo(file2));
            }
        }

    }