Question

我正在尝试根据this问题将值传递给来自活动的广播接收器。

然而，这样做会导致我的应用程序崩溃。这是我的活动代码。

private void setAlarm(Calendar targetCal)
{

    Intent in = new Intent("my.action.string");
    in.putExtra("ALARM_NO", tempx);
    sendBroadcast(in);

    Intent alarmintent = new Intent(AddAlarm.this, AlarmReceiver.class);
    PendingIntent sender = PendingIntent.getBroadcast(AddAlarm.this, pen, alarmintent, PendingIntent.FLAG_ONE_SHOT);
    AlarmManager alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE);
    alarmManager.setExact(AlarmManager.RTC_WAKEUP, targetCal.getTimeInMillis(), sender);


}

这里也是广播接收器代码：

public void onReceive(final Context context, Intent intent) {
    int state;
    String action = intent.getAction();

    Log.i("Receiver", "Broadcast received: " + action);

    if(action.equals("my.action.string"))
    {
        state = intent.getIntExtra("ALARM_NO",0);

    }

    if(state==1) {

        //intent to call the activity which shows on ringing
        Intent myIntent = new Intent(context, Time_Date.class);
        myIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(myIntent);
    }

    if(state==2)
    {
        //intent to call the activity which shows on ringing
        Intent myIntent = new Intent(context, AlarmLaunch2.class);
        myIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        context.startActivity(myIntent);
    }

这就是我在logcat中获得的。

> 07-21 16:40:40.769  26721-26721/zyia.alarm.zyia.zyia E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: zyia.alarm.zyia.zyia, PID: 26721
    java.lang.RuntimeException: Unable to start receiver zyia.alarm.zyia.zyia.AlarmReceiver: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
            at android.app.ActivityThread.handleReceiver(ActivityThread.java:2616)
            at android.app.ActivityThread.access$1700(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1380)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.String.equals(java.lang.Object)' on a null object reference
            at zyia.alarm.zyia.zyia.AlarmReceiver.onReceive(AlarmReceiver.java:29)
            at android.app.ActivityThread.handleReceiver(ActivityThread.java:2609)
            at android.app.ActivityThread.access$1700(ActivityThread.java:151)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1380)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5254)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

那么，什么导致空指针异常？以及如何解决这个问题？任何帮助将不胜感激。

Answer 1

你应该这样做：

private void setAlarm(Calendar targetCal)
{
    Intent alarmintent = new Intent(AddAlarm.this, AlarmReceiver.class);
    alarmintent.putExtra("ALARM_NO", tempx);
    alarmintent.setAction("my.action.string");
    PendingIntent sender = PendingIntent.getBroadcast(AddAlarm.this, pen, alarmintent, PendingIntent.FLAG_ONE_SHOT);

    AlarmManager alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE);
    alarmManager.setExact(AlarmManager.RTC_WAKEUP, targetCal.getTimeInMillis(), sender);


}

alarmintent.setAction（＆＃34; my.action.string＆＃34）;

Answer 2

您可以使用putExtra本身进行比较

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="more">click for more</div>
<div class="dropdown">Droppie down</div>

广播接收器中的
getStringExtra（＆＃34; action＆＃34;）

尝试将值传递给来自Activity的广播接收器崩溃应用程序

2 个答案: