Question

我正在使用以下代码，

public class Live extends ActionBarActivity {
super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_live);

        Long time = new GregorianCalendar().getTimeInMillis()+10*1000;

        Intent intentAlarm = new Intent(this, AlarmReceiver.class);

        AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
        alarmIntent=PendingIntent.getBroadcast(this, 1, intentAlarm, 0);

        alarmManager.set(AlarmManager.RTC_WAKEUP,time, alarmIntent);

        alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(),1000 * 10, alarmIntent);

        Toast.makeText(this, "Alarm Manager calling....", Toast.LENGTH_LONG).show();
}

在我的清单文件中，我也包括以下行 <receiver android:name=".AlarmReceiver"/>

我的AlarmReceiver Class只显示Toast

public class AlarmReceiver extends BroadcastReceiver
{
@Override
    public void onReceive(Context context, Intent intent)
    {
                 Toast.makeText(context,"Alarm ringing",Toast.LENGTH_SHORT).show();
    }
}

所以当我启动Application时，它会给我空指针异常Log cat

    05-07 14:27:49.192: E/AndroidRuntime(17793): FATAL EXCEPTION: main
05-07 14:27:49.192: E/AndroidRuntime(17793): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.livestream/com.example.livestream.Live}: java.lang.NullPointerException
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2114)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2139)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.ActivityThread.access$700(ActivityThread.java:143)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.os.Handler.dispatchMessage(Handler.java:99)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.os.Looper.loop(Looper.java:137)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.ActivityThread.main(ActivityThread.java:4960)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at java.lang.reflect.Method.invokeNative(Native Method)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at java.lang.reflect.Method.invoke(Method.java:511)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at dalvik.system.NativeStart.main(Native Method)
05-07 14:27:49.192: E/AndroidRuntime(17793): Caused by: java.lang.NullPointerException
05-07 14:27:49.192: E/AndroidRuntime(17793):    at com.example.livestream.Live.onCreate(Live.java:63)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.Activity.performCreate(Activity.java:5203)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
05-07 14:27:49.192: E/AndroidRuntime(17793):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2078)
05-07 14:27:49.192: E/AndroidRuntime(17793):    ... 11 more

你能告诉我哪里出错了吗？

Answer 1

您应该尝试删除set方法

 alarmManager.set(AlarmManager.RTC_WAKEUP,time, alarmIntent);

并仅使用setRepeating（如果您想重复该服务，否则请删除setRepeating）

在此之后，您必须创建一个扩展IntentService的类并插入方法onHandleIntent

@Override
protected void onHandleIntent(Intent intent) {
    ..code here.. (toast example)
}

之后，在Receiver类上，重写onReceiver方法并插入调用服务的意图

Intent i = new Intent(context,IntentService);
context.startService(i);

在最后一步中，在Manifest中添加服务信息（如接收者）

<service android:name=".name of your class"
    android:exported="true" />  <-I write also this

警报管理器崩溃了

1 个答案: