NoClassDefFoundError 当类明显在项目中时答案

【问题标题】：NoClassDefFoundError when class is clearly in projectNoClassDefFoundError 当类明显在项目中时
【发布时间】：2013-06-25 05:52:32
【问题描述】：

当无法找到的类清楚地在项目中时，我收到 NoClassDefFoundError。

错误实际上发生在 AsyncTask 中：

    public class PrefAuth extends AsyncTask<SharedPreferences,Object, Boolean> {

    @Override
    protected Boolean doInBackground(SharedPreferences... params) {
        return TwitterUtils.isAuthenticated(params[0]);
    }

    @Override
    protected void onPostExecute(Boolean isAuthenticated) {
        if (isAuthenticated) {
            GlobalAppContext.setTwitterFlag(true);
            Log.i("here", "isAuthenticated is true");
            Intent i = new Intent(getApplicationContext(), MainActivity.class);
            startActivity(i);
        }
        else {
            Log.i("here", "isAuthenticated is false");
            Intent i = new Intent(getApplicationContext(), LoginActivity.class); 
            startActivity(i);
        }
    }
}

错误指向return TwitterUtils.isAuthenticated(params[0]); 行。 TwitterUtils 是一个引用 Twitter4j 的类。我已经尝试在类路径上进行排序和导出，将 Twitter4j 移到顶部。我试过清理和重建。有谁知道为什么找不到课程？ Logcat 如下：

06-25 00:40:42.021: E/AndroidRuntime(5078): FATAL EXCEPTION: AsyncTask #1
06-25 00:40:42.021: E/AndroidRuntime(5078): java.lang.RuntimeException: An error occured while executing doInBackground()
06-25 00:40:42.021: E/AndroidRuntime(5078):     at android.os.AsyncTask$3.done(AsyncTask.java:200)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.util.concurrent.FutureTask.setException(FutureTask.java:125)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.util.concurrent.FutureTask.run(FutureTask.java:138)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.lang.Thread.run(Thread.java:1027)
06-25 00:40:42.021: E/AndroidRuntime(5078): Caused by: java.lang.NoClassDefFoundError: twitter4j.auth.AccessToken
06-25 00:40:42.021: E/AndroidRuntime(5078):     at com.tforan.blobtag4.twitter.TwitterUtils.isAuthenticated(TwitterUtils.java:17)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at com.tforan.blobtag4.SplashActivity$PrefAuth.doInBackground(SplashActivity.java:41)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at com.tforan.blobtag4.SplashActivity$PrefAuth.doInBackground(SplashActivity.java:1)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at android.os.AsyncTask$2.call(AsyncTask.java:185)
06-25 00:40:42.021: E/AndroidRuntime(5078):     at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306)
06-25 00:40:42.021: E/AndroidRuntime(5078):     ... 4 more

【问题讨论】：

你添加的是库项目还是jar？

标签： android noclassdeffounderror twitter4j

【解决方案1】：

右键单击项目>转到属性> Java构建路径>订购和导出>检查“Android私有库”

然后清理并构建项目，然后运行项目。

如果您已导出到您的项目中，还请检查其他 jar 文件。

希望对你有所帮助。

【讨论】：