Java 批量修改文件后缀

import java.io.*;

public class test {

  public void reName(String path, String from, String to) {

    File f = new File(path);

    File[] fs = f.listFiles();

    for (int i = ; i < fs.length; ++i) {

      File f2 = fs[i];

      if (f2.isDirectory()) {

        reName(f2.getPath(), from, to);

      } else {

        String name = f2.getName();

          if (name.endsWith(from)) {

          f2.renameTo(new File(f2.getParent() + "/" + name.substring(, name.indexOf(from)) + to));

        }

      }

    }

  }

  public static void main(String[] args) {

   test rf = new test();

    rf.reName("C:/Documents and Settings/xxxxx/Desktop/astaxie", ".md",".txt");

  }

}