Android异步任务错误

Question

我是新来的android和与AsyncTask实践短信应用程序。当我在模拟器应用程序上运行它时，无法启动。致命异常AsyncTAsk＃1发生错误。 我正在尝试使用AsyncTask填充收件箱。 Plz帮助。

public class Welcome extends Activity implements OnClickListener{ 
ListView smslist; 
Cursor cursor; 
Context context; 
SimpleCursorAdapter mcursor; 
Button button; 
private static final String TAG = "ADA CLASS"; 
private static final String TAG1 = "ADAPTE CLASS"; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_welcome); 
    button= (Button) findViewById(R.id.button1); 
    button.setOnClickListener(this); 
    smslist = (ListView) findViewById(R.id.listView1); 

    new thrd().execute(context); 
} 

    class thrd extends AsyncTask<Context,Void,SimpleCursorAdapter>{ 
     String [] a= {"address", "body","date"}; 
     int[] b={R.id.textView1,R.id.textView2,R.id.textView4}; 
     @Override 
     protected SimpleCursorAdapter doInBackground(Context... params) { 
      Context c= params[0]; 
      Uri smsuri = Uri.parse("content://sms/inbox"); 
      cursor=getContentResolver().query(smsuri, null, null ,null,null); 
      mcursor=new SimpleCursorAdapter(c, R.layout.row, cursor, a,b, 0); 
      return mcursor; 
     } 

     @Override 
     protected void onPostExecute(SimpleCursorAdapter result) { 
      smslist.setAdapter(result); 
     } 
    } 

@Override 
public void onClick(View v) { 
    Intent intent=new Intent(this, SendSMS.class); 
    startActivity(intent); 

} 

}

Answer 1

请方面的价值。

上下文= getApplicationContext（）;