Android Question Audiofocus

Wal

Member
Licensed User
Can I tell if the app lost the Audiofocus ?
 

Wal

Member
Licensed User
I found this
http://developer.android.com/reference/android/media/AudioManager.OnAudioFocusChangeListener.html

B4X:
OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() {
    public void onAudioFocusChange(int focusChange) {
        if (focusChange == AUDIOFOCUS_LOSS_TRANSIENT
            // Pause playback
        } else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) {
            // Resume playback
        } else if (focusChange == AudioManager.AUDIOFOCUS_LOSS) {
            am.unregisterMediaButtonEventReceiver(RemoteControlReceiver);
            am.abandonAudioFocus(afChangeListener);
            // Stop playback
        }
    }
};
B4X:
OnAudioFocusChangeListener afChangeListener = new OnAudioFocusChangeListener() {
    public void onAudioFocusChange(int focusChange) {
        if (focusChange == AUDIOFOCUS_LOSS_TRANSIENT_CAN_DUCK) {
            // Lower the volume
        } else if (focusChange == AudioManager.AUDIOFOCUS_GAIN) {
            // Raise it back to normal
        }
    }
};
Can I translate that into B4A ?
 

Erel

Administrator
Staff member
Licensed User
Try this code:
B4X:
Sub Activity_Create(FirstTime As Boolean)
   Dim jo As JavaObject
   jo.InitializeContext
   jo = jo.RunMethod("getSystemService", Array("audio"))
   Dim event As Object = jo.CreateEventFromUI("android.media.AudioManager.OnAudioFocusChangeListener", _
     "audio", Null)
   Dim p As Phone
   Log(jo.RunMethod("requestAudioFocus", Array (event, p.VOLUME_MUSIC, 2))) '2 = AUDIOFOCUS_GAIN_TRANSIENT

End Sub


Sub audio_Event (MethodName As String, Args() As Object) As Object
   Log(MethodName)
   Return Null
End Sub
MethodName should be onAudioFocusChange when the relevant event fires.
 
Last edited:
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Wal

Member
Licensed User
The Code work's great, but in a service in debug mode not.

B4X:
Sub Service_Start (StartingIntent As Intent)
    Dim jo As JavaObject
    jo.InitializeContext   ' -->>>"java.lang.NoSuchFieldException: context"
       jo = jo.RunMethod("getSystemService", Array("audio"))
       Dim event As Object = jo.CreateEventFromUI("android.media.AudioManager.OnAudioFocusChangeListener", _
     "audio", Null)
       Dim p As Phone
       jo.RunMethod("requestAudioFocus", Array (event, p.VOLUME_MUSIC, 2))
    frequenz = 7
    Volume = 10
    OpenRadio
End Sub
 

Wal

Member
Licensed User
Thank Erel,
for your feedback.
Debug(legacy) - works
Release(obfuscated) - works
Release - works
Debug(rapid) - don't work

Core 4.01
JavaObject 2.01
Reflection 2.40

B4X:
Sub Service_Start (StartingIntent As Intent)
    Dim jo As JavaObject
    jo.InitializeContext  ' --->>> line: 25  (serial)
       jo = jo.RunMethod("getSystemService", Array("audio"))
       Dim event As Object = jo.CreateEventFromUI("android.media.AudioManager.OnAudioFocusChangeListener", _
     "audio", Null)
       Dim p As Phone
       jo.RunMethod("requestAudioFocus", Array (event, p.VOLUME_MUSIC, 2))
    OpenRadio
End Sub
B4X:
Installing file.
PackageAdded: package:b4a.example1
** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
** Service (serial) Create **
** Service (serial) Start **
Error occurred on line: 25 (serial)
java.lang.NoSuchFieldException: context
    at java.lang.Class.getDeclaredField(Class.java:890)
    at anywheresoftware.b4j.object.JavaObject.InitializeContext(JavaObject.java:64)
    at b4a.example1.serial._service_start(serial.java:1209)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:636)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:302)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:238)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:121)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:171)
    at b4a.example1.serial.handleStart(serial.java:71)
    at b4a.example1.serial.onStartCommand(serial.java:55)
    at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2894)
    at android.app.ActivityThread.access$2100(ActivityThread.java:151)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1401)
    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)
** Service (serial) Start **
java.lang.RuntimeException: Unable to start service b4a.example1.serial@352afceb with Intent { cmp=b4a.example1/.serial }: java.lang.RuntimeException: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.reflect.Method.getName()' on a null object reference
    at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2911)
    at android.app.ActivityThread.access$2100(ActivityThread.java:151)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1401)
    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.RuntimeException: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.reflect.Method.getName()' on a null object reference
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:148)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:171)
    at b4a.example1.serial.handleStart(serial.java:71)
    at b4a.example1.serial.onStartCommand(serial.java:55)
    at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2894)
    ... 9 more
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.reflect.Method.getName()' on a null object reference
    at anywheresoftware.b4a.shell.Shell.runGoodChain(Shell.java:406)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:248)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:238)
    at java.lang.reflect.Method.invoke(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:372)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:121)
    ... 13 more
 
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