Android 通过广播发送数据

服务

 public class MainActivity extends Activity implements SurfaceHolder.Callback 
{
private Intent intent;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);


       if (activityReceiver != null)
{ 
       IntentFilter intentFilter = new IntentFilter();
      registerReceiver(activityReceiver, intentFilter);
}

    intent = new Intent(this, Service.class);
    startService(intent);

    }

 private BroadcastReceiver activityReceiver = new BroadcastReceiver(){
    public void onReceive(Context context, Intent intent) {
    int value=intent.getIntExtra("VALUE", 0);
    txtData.setText(""+value);
    }}

}

}

---

我试图使用广播将一个整数值从服务发送到活动，并在活动中的文本框中显示该整数值。这很简单，但我的程序还是崩溃了。这是我代码的一部分，我添加了广播代码。谁能告诉我这有什么问题吗？还有什么需要添加的吗？

在清单中声明服务

public class Service extends IOIOService {
//Intent intent=new Intent(this, MainActivity.class);
private final int BUTTON_PIN = 34;
@Override
protected IOIOLooper createIOIOLooper() {
    return new BaseIOIOLooper() {
        private DigitalOutput led_;
        private DigitalInput mButton;
        int  oneTime = 0;



        @Override
        protected void setup() throws ConnectionLostException,
                InterruptedException {
            led_ = ioio_.openDigitalOutput(IOIO.LED_PIN);
            mButton = ioio_.openDigitalInput(BUTTON_PIN, DigitalInput.Spec.Mode.PULL_UP);
        }

        @Override
        public void loop() throws ConnectionLostException,
                InterruptedException {

             final boolean reading1 = mButton.read();
             if (reading1) 
             {
                 led_.write(false);
                 if(oneTime == 0)
                 {
                                             Intent intent = new Intent();
                     intent.putExtra("VALUE", 100);
                     sendBroadcast(intent);
                     oneTime = 1;
                 }

                          } 
             else 

             {
                               led_.write(true);
                             }
            Thread.sleep(100);
              }

    };
}
}
  @Override
public void onStart(Intent intent, int startId) {
    super.onStart(intent, startId);
    NotificationManager nm = (NotificationManager) getSystemService(NOTIFICATION_SERVICE);
    if (intent != null && intent.getAction() != null
            && intent.getAction().equals("stop")) {
        // User clicked the notification. Need to stop the service.
        nm.cancel(0);
        stopSelf();
    } else 
    {
        // Service starting. Create a notification.
        Notification notification = new Notification(
                R.drawable.ic_launcher, "IOIO service running",
                System.currentTimeMillis());
        notification
                .setLatestEventInfo(this, "IOIO Service", "Click to stop",
                        PendingIntent.getService(this, 0, new Intent(
                                "stop", null, this, this.getClass()), 0));
        notification.flags |= Notification.FLAG_ONGOING_EVENT;
        nm.notify(0, notification);
    }
}

@Override
public IBinder onBind(Intent arg0) {
    return(null);

}

在

onCreate（）中更改以下行：

<service
                android:name=".Service">
 </service>

为此：

   intent = new Intent(this, Service.class);
    startService(new Intent(this, Service.class));

编辑：

intent = new Intent(this, Service.class);
startService(intent);

并在活动的
onreceive（）方法中获取值

在活动中注册广播：

//send broadcast from activity to all receivers listening to the action 
        Intent intent = new Intent();
        intent.putExtra("VALUE", 100);
        sendBroadcast(intent);

发布您的日志，同时发布您的IOIOS服务代码。@sush它已经存在了der@user3040168是的，它在那里，但是它被延长了。原始代码位于IOIOService类中。希望扩展服务类及其正确性，否则用这段代码很难找出问题所在。看看我的答案。希望它能帮助我们更早地尝试它…仍然认为问题在于这行
Intent-Intent=new-Intent（this，MainActivity.class）在您的服务类中。因为它无法获取上下文。只需注释这一行，然后选中@User3040168“是”，它工作时没有崩溃，但服务中的代码没有执行……整数没有传递。在代码中，intent为null，这就是为什么它没有得到值的原因。@GrlHu但当我命令intent intent=new intent（this，MainActivity.class）；，它要求初始化“意图”意图；。。。dis行要求初始化“意图”…因为意图意图=新意图（这是MainActivity.class）；不使用
public class MainActivity extends Activity implements SurfaceHolder.Callback 
{
private Intent intent;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    intent = new Intent(this, Service.class);
    startService(intent);
if (activityReceiver != null)
  {
           IntentFilter intentFilter = new IntentFilter();
        //Map the intent filter to the receiver
         registerReceiver(activityReceiver, intentFilter);
  }

}

 private BroadcastReceiver activityReceiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {
        Toast.makeText(getApplicationContext(), "received message in activity..!", Toast.LENGTH_SHORT).show();
           int value=intent.getIntExtra("VALUE", 0);
           txtData.setText(value);
    }
};


 }

             // cuase for null pointer exception, intent is getting set as null first
then ur using putExtra method on it.  
              Intent intent = null;
                 intent.putExtra("VALUE", 100);
                 sendBroadcast(intent);
                 oneTime = 1;