是否可以从BrodcastReceiver启动警报对话框?
问题描述:
我正在创建一个闹钟应用程序,在指定的时间,AlarmBroadcast
启动。 我想在指定的时间添加Alert Dialog
。是否可以从BrodcastReceiver启动警报对话框?
这就是我所做的。
public class AlarmBrodcast extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
final AlertDialog alertDialog = new AlertDialog.Builder(context.getApplicationContext()).create();
alertDialog.setTitle("Delete Remainder");
alertDialog.setMessage("Are you sure you want to Delete this Remainder");
alertDialog.setButton(AlertDialog.BUTTON_POSITIVE, "Yes", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
alertDialog.dismiss();
}
});
alertDialog.setButton(AlertDialog.BUTTON_NEGATIVE, "No", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
alertDialog.dismiss();
}
});
alertDialog.show();
这给我下面的错误信息。
了java.lang.RuntimeException:无法实例化接收机 com.example.taha.alarmproject.AlarmBrodcast: java.lang.ClassCastException: com.example.taha.alarmproject.AlarmBrodcast不能转换到Android的 .content.BroadcastReceiver
编辑 MainActivity
Intent intent = new Intent(this, AlarmBrodcast.class);
intent.putExtra("message", "Alarm Message 00001");
PendingIntent pendingIntent = PendingIntent.getBroadcast(
this.getApplicationContext(), 234324243, intent, 0);
AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
/* alarmManager.set(AlarmManager.RTC_WAKEUP, cal.getTimeInMillis(), pendingIntent);*/
alarmManager.set(AlarmManager.RTC_WAKEUP, System.currentTimeMillis()
+ (i * 1000), pendingIntent);
Toast.makeText(this, "Alarm set in " + i + " seconds", Toast.LENGTH_LONG).show();
我也尝试从BrodcastReceiver
启动Activity
,但它也未能启动。
答
一个简单的解决方案就是使用Event
。这是你如何用一个漂亮的小库我在项目中使用做到这一点:
compile 'org.greenrobot:eventbus:3.0.0'
是一行添加到您的build.gradle
(模块级)文件。
这里的想法是在调用onReceive
时,使AlarmBroadcast
能够通知Activity
类。
创建一个Plain Old Java Object (POJO)
类来表示您的事件!现在
public class BroadCastEvent{
private boolean isCompleted;
BroadCastEvent(boolean completed){
this.isCompleted = completed;
}
//getter
public boolean isCompleted(){
return this.isCompleted;
}
}
,里面onReceive
方法您AlarmBroadcast
类:
EventBus.getDefault().post(new BroadCastEvent(true));
接下来,在您的活动,注册侦听此事件是这样的:
EventBus.getDefault().register(this);
然后重写此方法:
public void onEvent(BroadCastEvent event){
if(event.isCompleted()){
//show your dialog here or start next activity
}
}
接下来,方法的onDestroy里面注销eventbus:
@Override
public void onDestroy(){
super.onDestroy();
EventBus.getDefault().unregister(this);
}
这样可以使你的代码,并允许您,让您AlarmBroadcast类Publisher
和活动为您提供Subscriber
!
我希望这可以帮助,请让我知道它是怎么回事!
您是否在清单中添加了'receiver'? –
是的我添加了,我成功地能够打印吐司消息 – Kirmani88
请发布代码,你实例化广播接收机 – Lino