(转载)Just update ADT and Unable to resolve superclass errer appear-优快云博客

本文详细介绍了在使用Android开发工具（ADT）更新后，遇到MainActivity类无法链接的问题，并提供了通过调整Java Build Path和启用Android Private Libraries来解决此问题的方法。

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The error show after I update my ADT, the project is created before the update.

In Login Activity,

public class LoginActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

            // Do something here... if login success, Start another activity
        Intent i = new Intent(LoginActivity.this, MainActivity.class);
        LoginActivity.this.startActivity(i);
    }
.......
}

In MainActivity,

public class MainActivity extends FragmentActivity {
  protected void onCreate(Bundle savedInstanceState) {
    //......
  }
}

I try to remove all the code inside and back to a blank activity. The error is not happen because of the code inside the activity. I think is abut the extend FragmentActivity

Here is the error trace:

Unable to resolve superclass of Lhk/iactive/imoodle/activity/MainActivity; (15)
Link of class 'Lhk/iactive/imoodle/activity/MainActivity;' failed

I get this error after I update my ADT. I do some research on this topic. I try to import the android-support-v4.jar again and this do not fix the problem. I also read some blog like THIS ONE can not help me too :(

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解决方法：

For all projects (app and library):

Right click the project,

and choose PropertiesGo to Java Build Path-Order and Export.

Tick 'Android Private Libraries'