主要活动完成后如何显示服务中的Toast? [英] How to display Toast from a Service after main Activity finishes?

问题描述

更新:我不同意这是重复的-因为我正在寻找退出主应用程序并仍然从该服务显示Toast的方法.

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.

在一个非常简单的测试应用我有2个按钮:

单击任何按钮将运行带有相应操作字符串(打开"或闪光")的服务-

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

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);
    }

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，我的应用崩溃了:

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)

成为Android编程新手，我想知道如何显示从服务以正确的方式敬酒?

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 Home上看到Toasts(即设备屏幕上没有活动"，但仍然有Toasts).

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:我想从我的服务中监视信标设备，并显示一些Toasts文字-即使我的应用已关闭.

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将在不同的Thread中运行 因此，您正在android中不允许的线程中显示Toast

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

因此请更改您的代码

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();              
    }
});

从此服务中的死线程

IntentService将创建一个线程来处理新的意图，并在任务完成后立即终止它.因此，Toast将不受死线程的控制.

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.

当吐司显示在屏幕上时，您应该在控制台中看到一些例外情况.

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

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