issue with resolving activity for an intent - resolveActivityInfo()

Question

I am using resolveActivityInfo to determine if my app was set as a home launcher:

    PackageManager pm = getPackageManager();

    Intent intent = new Intent(Intent.ACTION_MAIN, null);
    intent.addCategory(Intent.CATEGORY_HOME);   

    userHomePackage = intent.resolveActivityInfo(pm, 0).packageName;
    userHomeActivityClass = intent.resolveActivityInfo(pm, 0).name;     
currentHomeLauncherName = intent.resolveActivityInfo(pm, 0).loadLabel(pm).toString();

it works great on emulator and three android devices I have on hands.

Recently I started getting error reports from my users and error log shows that resolveActivityInfo is failing. This happens only on a few phones running on android 2.1 update 1 as I can see. I've received already many positive comments on my app and a few negative because of this issue.

Any advice what could be wrong?

java.lang.NullPointerException
    at android.os.Parcel.readException(Parcel.java:1224)
    at android.os.Parcel.readException(Parcel.java:1206)
    at android.content.pm.IPackageManager$Stub$Proxy.resolveIntent(IPackageManager.java:1418)
    at android.app.ApplicationContext$ApplicationPackageManager.resolveActivity(ApplicationContext.java:2046)
    at android.content.Intent.resolveActivityInfo(Intent.java:3790)
    at com.myapp.myappname.Launcher.setAsHomeApplicationBeforeFroyo(Launcher.java:336)

OR

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.myappname/com.myapp.myappname.Launcher}: java.lang.NullPointerException
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2497)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2513)
    at android.app.ActivityThread.access$2200(ActivityThread.java:119)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1864)
    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$MethodAndArgsCaller.run(ZygoteInit.java:862)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:620)
    at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
    at android.os.Parcel.readException(Parcel.java:1224)
    at android.os.Parcel.readException(Parcel.java:1206)
    at android.content.pm.IPackageManager$Stub$Proxy.resolveIntent(IPackageManager.java:1418)
    at android.app.ApplicationContext$ApplicationPackageManager.resolveActivity(ApplicationContext.java:2046)
    at android.content.Intent.resolveActivityInfo(Intent.java:3790)
    at com.myapp.myappname.Launcher.showHomeChooserDialog(Launcher.java:141)
    at com.myapp.myappname.Launcher.showNextActivity(Launcher.java:122)
    at com.myapp.myappname.Launcher.onCreate(Launcher.java:59)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2460)
    ... 11 more
java.lang.NullPointerException
    at android.os.Parcel.readException(Parcel.java:1224)
    at android.os.Parcel.readException(Parcel.java:1206)
    at android.content.pm.IPackageManager$Stub$Proxy.resolveIntent(IPackageManager.java:1418)
    at android.app.ApplicationContext$ApplicationPackageManager.resolveActivity(ApplicationContext.java:2046)
    at android.content.Intent.resolveActivityInfo(Intent.java:3790)
    at com.myapp.myappname.Launcher.showHomeChooserDialog(Launcher.java:141)

Answer 1

Kevin from TeslaCoil Software here. Sorry for the delay in getting back to you. This is what I'm using to get the Home component in my apps:

public static ComponentName getHomeComponent(PackageManager PM) {
    Intent home_intent = new Intent("android.intent.action.MAIN");
    home_intent.addCategory("android.intent.category.HOME");
    home_intent.addCategory("android.intent.category.DEFAULT");

    ComponentName cn = home_intent.resolveActivity(PM);
    if (cn == null)
        Log.v(TAG, "[Default] package:null");
    else
        Log.v(TAG, "[Default] package:" + cn.getPackageName() + " class:" + cn.getClassName());

    return cn;
}

resolveActivity doesn't normally return null, as it seems to return the resolver activity if there is no default set. But on some phones or something it might return null just to keep things interesting. Perhaps resolveActivityInfo calls resolveActivity but doesn't handle the null case properly.