Java Question raise an activity sub from java class without having control over its "Initialize" (so BA object is null ?)

[abilio486software]

Hi,

I have a library (Activity kind), that does not have received an .Initialize from my B4A source code.

Hoever I pretend to call a sub (like raising an event) to the activity that is on screen.

I'm getting an error when call

if (BA.subExists( "pushy_msg")) {
   BA.raiseEventFromUI(this, "pushy_msg", notificationText);
}

telling that "ba" is null.

Error message:

{message=Ola!!!!}
Invoking push receiver via reflection: com.teste.PushReceiver2
MSG:Ola!!!!
Invoking push receiver via reflection failed
java.lang.reflect.InvocationTargetException
    at java.lang.reflect.Method.invoke(Native Method)
    at me.pushy.sdk.model.PushyBroadcastReceiver.execute(PushyBroadcastReceiver.java:22)
    at me.pushy.sdk.util.PushyBroadcastManager.sendBroadcast(PushyBroadcastManager.java:158)
    at me.pushy.sdk.util.PushyBroadcastManager.publishNotification(PushyBroadcastManager.java:99)
    at me.pushy.sdk.util.PushyMqttConnection.messageArrived(PushyMqttConnection.java:251)
    at me.pushy.sdk.lib.paho.internal.CommsCallback.deliverMessage(CommsCallback.java:475)
    at me.pushy.sdk.lib.paho.internal.CommsCallback.handleMessage(CommsCallback.java:379)
    at me.pushy.sdk.lib.paho.internal.CommsCallback.run(CommsCallback.java:183)
    at java.lang.Thread.run(Thread.java:818)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean anywheresoftware.b4a.BA.subExists(java.lang.String)' on a null object reference
    at com.teste.PushReceiver2.onReceive(PushReceiver2.java:58)
    ... 9 more

How can I use ba from an external class that is automatically initialized not by me but from an external SDK?

How to force BA to evoke the current activity?

 

[Erel]

You can't raise a regular event without a BA context.
My guess is that you are making a mistake to use a library for MQTT based push notifications. It will be simpler and will work better to implement it yourself with jMQTT.

 

[abilio486software]

I'm implementing Pushy.me and it's working but at this stage without triggering to the activity.
For this project I would opt to usr Pushy.me for several reasons.
It is possible to declare on a Java public var the actual BA context and use it from my library?

 

[Erel]

No. The BA context (for events) must be passed from the B4A code. You can do different things like sending an intent to the activity or probably better a service.

 

[abilio486software]

Hi Erel, It's working without BA context or raise event.

I found with Reflection the way to call a B4A activity method from a pure java class:

        // "notificationText" is the String with the notification text to send to main activity
        BA.Log("MSG:" + notificationText );
        // Locate the activity
        ActivityManager activityManager = (ActivityManager)    context.getSystemService("activity");
        List<ActivityManager.RunningTaskInfo> taskInfo = activityManager.getRunningTasks(1);
        String currentTopActivity = taskInfo.get(0).topActivity.getClassName();
        // This is the top activity
        BA.Log("MSG ACTIVITY:" + currentTopActivity );
        // Try to instance the object to call the remote method
        try {
            Class myClass = Class.forName(currentTopActivity); 
            Activity act;
            act = (Activity) myClass.newInstance();
            //Get the list of possible methods held in this object.
            Method[] methods = myClass.getMethods();

            // iterate through them
            //for (Method method : methods) {
            //  BA.Log("" + this.getClass().getName() + "--------------------------");
            // BA.Log("" + this.getClass().getName()+ "Method: " + method.getName());
            // BA.Log("" + this.getClass().getName()+ "Return Type: " + method.getReturnType());
            // BA.Log("" + this.getClass().getName()+ "Class: " + method.getClass());
            // BA.Log("" + this.getClass().getName()+ "Declaring Class: " + method.getDeclaringClass());
            //}
            // BA.Log("" + this.getClass().getName()+"--------------------------");
       
                // But I now exactly the method I want
            Method setNameMethod = myClass.getMethod("_recebeu_mensagem", String.class);
            // Now call the method of main activity 
            setNameMethod.invoke(act, notificationText); // pass arg
 
      }
      catch( Exception e){
        
          BA.Log("ERRO!!! = " + e);
      }

I hope it can be usefull for someone else

Thanks,

Abilio