“如何度过难关”；java lang运行时异常执行doinbackground时出错；错误？

嗨，我正在尝试创建一个android应用程序来与Github Api交互。 当我尝试使用ASyncTask的一个简单示例时，我使用翻新库来实现这一点

异步任务致命异常

错误，我认为我在这里做得很好，我无法理解遗漏了什么或错了什么
不明白为什么，请帮忙

代码示例：

private class Process extends AsyncTask<String,String,String>
    {

        @Override
        protected String doInBackground(String... params) {
            // TODO Auto-generated method stub
            RestAdapter restAdapter;
            String url= params[0];
            restAdapter = new RestAdapter.Builder()
            .setEndpoint(url)
            .build();


        // Create an instance of our GitHub API interface.
         GitHub github = restAdapter.create(GitHub.class);

        // Fetch and print a list of the contributors to this library.
        List<Contributor> contributors = github.contributors("square", "retrofit");

       return contributors.toString();

        }

        @Override
        protected void onPostExecute(String result) {
            // TODO Auto-generated method stub
            text.setText(result);
        }

    }

---

原因：java.lang.NoClassDefFoundError:Reformation.RestAdapter$Builder

这是什么意思？更新库丢失了还是什么？我在项目中添加了改装库！可能未正确添加。尝试再次添加，清理构建，然后再次运行。刚刚尝试，仍然没有运气：/。。还有其他建议吗？@Dhruti-或者你能给我推荐其他android的Rest库吗？

09-02 07:32:55.132: E/AndroidRuntime(2830): FATAL EXCEPTION: AsyncTask #1
09-02 07:32:55.132: E/AndroidRuntime(2830): Process: com.example.codemymobile, PID: 2830
09-02 07:32:55.132: E/AndroidRuntime(2830): java.lang.RuntimeException: An error occured while executing doInBackground()
09-02 07:32:55.132: E/AndroidRuntime(2830):     at android.os.AsyncTask$3.done(AsyncTask.java:300)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at java.util.concurrent.FutureTask.run(FutureTask.java:242)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at java.lang.Thread.run(Thread.java:841)
09-02 07:32:55.132: E/AndroidRuntime(2830): Caused by: java.lang.NoClassDefFoundError: retrofit.RestAdapter$Builder
09-02 07:32:55.132: E/AndroidRuntime(2830):     at com.example.codemymobile.MainActivity$Process.doInBackground(MainActivity.java:50)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at com.example.codemymobile.MainActivity$Process.doInBackground(MainActivity.java:1)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at android.os.AsyncTask$2.call(AsyncTask.java:288)
09-02 07:32:55.132: E/AndroidRuntime(2830):     at java.util.concurrent.FutureTask.run(FutureTask.java:237)
09-02 07:32:55.132: E/AndroidRuntime(2830):     ... 4 more