java - 将 xml 导入到 Android Studio 文本

Question

德斯..

我有下面的代码从 RSS 网页导入 XML，以将 xml 中的文本显示到我的应用程序，在 list 中添加了互联网和网络状态的权限..

import...
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        new Thread() {
            final TextView urlTextOut = (TextView) findViewById(R.id.result);
            final StringBuilder text = new StringBuilder();
            @Override
            public void run() {
                try
                {
                    String str;
                    URL url = new URL("My url");
                    BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
                    while ((str = in.readLine()) != null) {
                        text.append(str);
                    }
                    in.close();
                } catch (IOException ignored)
                {
                }
                urlTextOut.setText(text);
            }
        }.start();
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

但是当我在 Android 模拟器或手机上直接运行它时出现以下错误:

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

.... 你能帮我解决这个问题

Answer 1

嗨，正如我告诉您的，您创建了新线程，并在其中更新了 TextView 。这就是你更新的 View 不是同一个线程的根本原因。理想情况下，在 android 中只有 UI 线程可以触摸 View 进行更新。让我们来吹一下你的代码。

import...
public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final TextView urlTextOut = (TextView) findViewById(R.id.result);
        new Thread() {

            final StringBuilder text = new StringBuilder();
            @Override
            public void run() {
                try
                {
                    String str;
                    URL url = new URL("My url");
                    BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
                    while ((str = in.readLine()) != null) {
                        text.append(str);
                    }
                    in.close();
                } catch (IOException ignored)
                {
                }
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            urlTextOut.setText(text);
                        }
                    });

            }
        }.start();
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}