Question

因此，由于我对Android开发完全陌生，我想为我的新Moto 360（Google Wear）创建一个简单的应用程序，以显示从网页中提取的一些内容。不幸的是，我收到了这个错误：

 android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.

如何将修改TextView文本值的部分移动到主类？

public class MyActivity extends Activity {

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

    TextView mTextView = (TextView)findViewById(R.id.text);

    myAsyncTask mTask = new myAsyncTask();
    mTask.execute("http://ephemeraltech.com/demo/android_tutorial20.php");


    /* final WatchViewStub stub = (WatchViewStub) findViewById(R.id.watch_view_stub);
    stub.setOnLayoutInflatedListener(new WatchViewStub.OnLayoutInflatedListener() {
        @Override
        public void onLayoutInflated(WatchViewStub stub) {
            mTextView = (TextView) stub.findViewById(R.id.text);
        }
    }); */
}

并且AsyncTask类是

private class myAsyncTask extends AsyncTask<String,Void,Void> {

    @Override
    protected void onPreExecute() {
    }

    @Override
    protected Void doInBackground(String... str) {
        TextView mTextView = (TextView)findViewById(R.id.text);
        try {

            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://ephemeraltech.com/demo/android_tutorial20.php");
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            InputStream webs = entity.getContent();
            try {
                BufferedReader reader = new BufferedReader(new InputStreamReader(webs,"iso-8859-1"),8);
                mTextView.setText(reader.readLine());
                webs.close();
            } catch(Exception e){
                mTextView.setText("HI");
            }
        } catch (Exception e) {
            mTextView.setText(e.toString());
        }

        return null;
    }

}

protected void onPostExecute(String str) {
}

}

Answer 1

您无法从doInBackground更新用户界面。将该代码移至onPostExecute

//In doInBackground

try {
    BufferedReader reader = new BufferedReader(new InputStreamReader(webs,"iso-8859-1"),8);
    resultText = reader.readLine();
    webs.close();
} catch(Exception e){
    resultText = "HI";
}
.  
.
.
// onPostExecute method
protected void onPostExecute(String str) {
    mTextView.setText(resultText);
}

将resultText声明为全局字符串

Answer 2

doInBackground（）方法在后台线程上执行 - 而不是UI线程。只有UI线程才能修改视图。

AyncTask类提供onProgressUpdate（）方法和onPostExecute（）方法，该方法挂钩到UI线程以分别显示进度或结果。

如果要在执行AsyncTask时显示进度，请将用于设置TextView中文本的代码移动到onProgressUpdate（）方法。如果您希望它在执行AsyncTask结束时显示，则将其移至onPostExecute（）。

如何将视图修改为主类的代码

2 个答案: