如何从服务显示吐司？发送消息到处理程序上的死线 [英] How to display Toast from a Service? Sending message to a Handler on a dead thread

问题描述

更新：我不同意这是一个重复的 - 因为我在寻找一种方式来退出主应用程序，仍然从服务显示吐司

UPDATE: I don't agree that this is a duplicate - because I am seeking for a way to exit the main app and still show a Toast from the service.

在<一个href=\"https://github.com/afarber/android-newbie/tree/q12/MyNotification/src/de/afarber/mynotification\"相对=nofollow>一个非常简单的测试应用我有2个按钮：

点击任何按钮，将运行一个相应的操作字符串即服务（打开或闪） -

Clicking any of the buttons will run a service with a corresponding action string ("open" or "flash") -

<一个href=\"https://github.com/afarber/android-newbie/blob/q12/MyNotification/src/de/afarber/mynotification/OpenActivity.java\"相对=nofollow> OpenActivity.java ：

public class OpenActivity extends Activity {
    private Intent mServiceIntent;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_open);
        mServiceIntent = new Intent(this, RegionService.class);
   }

    public void openCar(View v) {
        mServiceIntent.setAction("open");
        startService(mServiceIntent);
    }

<一个href=\"https://github.com/afarber/android-newbie/blob/q12/MyNotification/src/de/afarber/mynotification/RegionService.java\"相对=nofollow> RegionService.java ：

public class RegionService extends IntentService {
    private static final String TAG = "RegionService";

    @Override
    protected void onHandleIntent(Intent intent) {
        Log.d(TAG, "Received an intent: " + intent);
        String action = intent.getAction();
        Log.d(TAG, "Received an action: " + action);

        if(action.equals("open")) {
            Toast.makeText(this, 
                    getString(R.string.car_opened), 
                    Toast.LENGTH_SHORT).show();
        } 

不幸的是我的应用程序崩溃，

Unfortunately my app crashes with:

D/RegionService(24506): Received an intent: Intent { act=open cmp=de.afarber.mynotification/.RegionService }

D/RegionService(24506): Received an action: open

W/MessageQueue(24506): Handler (android.os.Handler) {422768a8} sending message to a Handler on a dead thread
W/MessageQueue(24506): java.lang.RuntimeException: Handler (android.os.Handler) {422768a8} sending message to a Handler on a dead thread
W/MessageQueue(24506):  at android.os.MessageQueue.enqueueMessage(MessageQueue.java:320)
W/MessageQueue(24506):  at android.os.Handler.enqueueMessage(Handler.java:626)
W/MessageQueue(24506):  at android.os.Handler.sendMessageAtTime(Handler.java:595)
W/MessageQueue(24506):  at android.os.Handler.sendMessageDelayed(Handler.java:566)
W/MessageQueue(24506):  at android.os.Handler.post(Handler.java:326)
W/MessageQueue(24506):  at android.widget.Toast$TN.hide(Toast.java:370)
W/MessageQueue(24506):  at android.app.ITransientNotification$Stub.onTransact(ITransientNotification.java:54)
W/MessageQueue(24506):  at android.os.Binder.execTransact(Binder.java:412)
W/MessageQueue(24506):  at dalvik.system.NativeStart.run(Native Method)

作为一个Android编程的新手，我不知道如何显示从服务以正确的方式吐司？

Being an Android programming newbie I wonder How to display a Toast from Service in a correct way?

我想我已经在Android主看到祝酒词（即有设备屏幕上没有任何活动，仍然有祝酒词）。

I think I've already seen Toasts at Android Home (i.e. there was no Activity on the device screen and still there were Toasts).

我的背景：我想监视从我服务的灯塔设备，并显示一些文字祝酒词 - 即使我的应用程序已经关闭

My background: I would like to monitor a beacon device from my service and show some text Toasts - even when my app has been closed.

推荐答案

OnHandleIntent 将在歧线程中运行
所以你展示吐司中未在android系统允许一个线程

OnHandleIntent will run in a differant Thread so you are showing Toast in a thread which is not allowed in android

因此​​改变你的code这样的

so change your code like this

Handler handler = new Handler(Looper.getMainLooper());
handler.post(new Runnable() {

    @Override
    public void run() {
         Toast.makeText(getApplicationContext(), 
                       getString(R.string.car_opened), 
                       Toast.LENGTH_SHORT).show();              
    }
});

从这个<一个href=\"http://stackoverflow.com/questions/3296639/toast-created-in-an-intentservice-never-goes-away/16766109#16766109\">dead线程服务

IntentService将创建一个线程来处理新的意图，立即终止它一旦任务完成。因此，面包会出1死线程控制。

IntentService will create a thread to handle the new intent, and terminated it immediately once the task has done. So, the Toast will be out of controlled by a dead thread.

您应该在控制台中看到一些例外的时候敬酒显示在屏幕上。

You should see some exceptions in the console when the toast showing on the screen.

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