Develop Reference

App Crashes after a long time of inactivity

I get the following error when the app is not in use for longer than 15-30 mins. I am really new into this and app is currently published but I don't know how to fix this error. I see it's because of the ZoomButtonsController. Please see the following what I am doing in my code.
Code
webview.getSettings().setBuiltInZoomControls(true);
if (Build.VERSION.SDK_INT > Build.VERSION_CODES.HONEYCOMB) {
webview.getSettings().setDisplayZoomControls(false);
}
Error
java.lang.IllegalArgumentException: Receiver not registered: android.widget.ZoomButtonsController$1#40813248
at android.app.LoadedApk.forgetReceiverDispatcher(LoadedApk.java:610)
at android.app.ContextImpl.unregisterReceiver(ContextImpl.java:878)
at android.content.ContextWrapper.unregisterReceiver(ContextWrapper.java:331)
at android.widget.ZoomButtonsController.setVisible(ZoomButtonsController.java:404)
at android.widget.ZoomButtonsController$2.handleMessage(ZoomButtonsController.java:178)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:3691)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:847)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:605)
at dalvik.system.NativeStart.main(Native Method)

How to avoid class not found exception in android

I am getting class not found exception on some android devices, it's happening only on some devices.
This is the call-stack i have got,
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.picframes.android/com.picframes.android.first}: java.lang.ClassNotFoundException: com.picframes.android.first
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2240)
at android.app.ActivityThread.access$600(ActivityThread.java:139)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1262)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:156)
at android.app.ActivityThread.main(ActivityThread.java:4987)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.ClassNotFoundException: com.picframes.android.first
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
at android.app.Instrumentation.newActivity(Instrumentation.java:1039)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
Any suggestions for resolving this problem, I could not reproduce this problem on my device.

On devices with which android version program works and where it doesn't work? I am not sure if this is the case but you probably get this error on older devices, is that right? You should make sure that all the functionality of your program is available on older systems. Use your manifest file:
<uses-sdk android:minSdkVersion="integer"
android:targetSdkVersion="integer"
android:maxSdkVersion="integer" />
to define minimum sdk version, and you will get errors in your code if you are trying to use features that are not available on the device that you target.

android error java.lang.NoClassDefFoundError

I have android app in market so I get this error but I don't know why.
Exception class java.lang.NoClassDefFoundError
Source method MainActivity.onCreate()
java.lang.NoClassDefFoundError: android.app.DownloadManager
at com.example.viewpagerexample.MainActivity.onCreate(MainActivity.java:182)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1069)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2751)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2803)
at android.app.ActivityThread.access$2300(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2136)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:144)
at android.app.ActivityThread.main(ActivityThread.java:4937)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)

DownloadManager was added on API level 9 (aka Gingerbread).
My guess you declared minSDK as lower than 9 in your AndroidManifest.xml
If that is the case, you need to devise a workaround for users using older Android version.
You can check on which version your app is running by using the following code:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.GINGERBREAD) {
// Use DownloadManager
}
else {
// Workaround
}

Error: Alarm (Unable to start receiver)

Please advice what the problem is with my code...
I am constantly getting this exception any suggestion would be really appreciated.
STACK_TRACE=java.lang.RuntimeException: Unable to start receiver com.platinumapps.platinumtasks.AlarmReceiver: java.lang.NullPointerException
at android.app.ActivityThread.handleReceiver(ActivityThread.java:1975)
at android.app.ActivityThread.access$1400(ActivityThread.java:122)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1074)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:132)
at android.app.ActivityThread.main(ActivityThread.java:4123)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.platinumapps.platinumtasks.AlarmReceiver.onReceive(AlarmReceiver.java:109)
at android.app.ActivityThread.handleReceiver(ActivityThread.java:1968)
... 10 more
java.lang.NullPointerException
at com.platinumapps.platinumtasks.AlarmReceiver.onReceive(AlarmReceiver.java:109)
at android.app.ActivityThread.handleReceiver(ActivityThread.java:1968)
at android.app.ActivityThread.access$1400(ActivityThread.java:122)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1074)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:132)
at android.app.ActivityThread.main(ActivityThread.java:4123)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:491)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
at dalvik.system.NativeStart.main(Native Method)

Its a nullpointer exception.
Means that something you are calling isn't initiated correctly, Or that you dont have access to that part(ei. havn't decalred activities in AndroidManifest. Or havn't included the rights jars etc.)
If you want better help, post the code you are working with.

AdWhirl with Admob bug fix

Updated to the latest version of AdWhirl and AdMob SDK but getting a known error from the AdMob SDK in Android 2.1-update1. Found in this thread https://groups.google.com/forum/#!topic/google-admob-ads-sdk/cNxRgIUHJH0
but it refers to only and AdMob fix not AdWhirl any clue what changes can be made to the AdWhirl SDK to fix this?
Thanks In Advance!
java.lang.NullPointerException
at android.webkit.WebView.getSettings(WebView.java:2791)
at android.webkit.WebView.onWindowFocusChanged(WebView.java:3616)
at android.view.View.dispatchWindowFocusChanged(View.java:3764)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:754)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:758)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:758)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:758)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:758)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:758)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:758)
at android.view.ViewRoot.handleMessage(ViewRoot.java:1819)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:123)
at android.app.ActivityThread.main(ActivityThread.java:4370)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:521)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
at dalvik.system.NativeStart.main(Native Method)
How about this one:
java.lang.NullPointerException
at com.adwhirl.AdWhirlLayout.handleAd(AdWhirlLayout.java:227)
at com.adwhirl.AdWhirlLayout.access$3(AdWhirlLayout.java:215)
at com.adwhirl.AdWhirlLayout$HandleAdRunnable.run(AdWhirlLayout.java:410)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3691)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:670)
at dalvik.system.NativeStart.main(Native Method)

The issue is not in the AdWhirl code, or even the AdMob code. This is a NullPointerException in the Android WebView, and there is no known workaround for the AdMob/AdWhirl code. This shouldn't be happening that often, but if it really is a deal breaker, you may want to turn down the number of requests you're sending to AdMob.

Yes, I also have this problem.
My workaround: extend AdWhirlLayout, override dispatchWindowFocusChanged and every other method that have this exception occurring and catch the exception.