从Android的辅助线程调用主线程

如何从Android的辅助线程调用主线程？

Answer 1

最简单的方法是从你的线程调用runOnUiThread（…）

activity.runOnUiThread(new Runnable() { public void run() { ... do your GUI stuff } }); 

Answer 2

我build议在同一个进程中交stream线程是在这些线程之间发送消息。 使用处理程序pipe理这种情况非常简单：

http://developer.android.com/reference/android/os/Handler.html

从Android文档中使用从UI线程处理昂贵工作的示例：

 public class MyActivity extends Activity { [ . . . ] // Need handler for callbacks to the UI thread final Handler mHandler = new Handler(); // Create runnable for posting final Runnable mUpdateResults = new Runnable() { public void run() { updateResultsInUi(); } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); [ . . . ] } protected void startLongRunningOperation() { // Fire off a thread to do some work that we shouldn't do directly in the UI thread Thread t = new Thread() { public void run() { mResults = doSomethingExpensive(); mHandler.post(mUpdateResults); } }; t.start(); } private void updateResultsInUi() { // Back in the UI thread -- update our UI elements based on the data in mResults [ . . . ] } } 

Answer 3

您将需要一个Handler ，将信息传递回主线程。

Answer 4

另外，最好记住，如果通过AsyncTask获得辅助线程，则可以select调用onProgressUpdate（） ， onPostExecute（）等来在主线程上工作。

Answer 5

使用HandlerThread的示例代码

 public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final Handler responseHandler = new Handler(Looper.getMainLooper()){ @Override public void handleMessage(Message msg) { //txtView.setText((String) msg.obj); Toast.makeText(MainActivity.this, "Result from UIHandlerThread:"+(int)msg.obj, Toast.LENGTH_LONG) .show(); } }; HandlerThread handlerThread = new HandlerThread("UIHandlerThread"){ public void run(){ /* Add your business logic to pupulate attributes in Message in place of sending Integer 5 as in example code */ Integer a = 5; Message msg = new Message(); msg.obj = a; responseHandler.sendMessage(msg); System.out.println(a); } }; handlerThread.start(); } } 

说明：

1. 在上面的例子中， HandlerThread在UI Thread的Handler上发布了一个Message ，该Message已经被UI Thread的Looper初始化了。

    final Handler responseHandler = new Handler(Looper.getMainLooper()) 

2. responseHandler.sendMessage(msg); 将Message从HandlerThread发送到UI线程Handler 。

3. handleMessage处理在MessageQueue收到的Message ，并在UI线程上显示Toast。