dachristenson
Kotlin and Android Development featuring Jetpack: End Ch. 11 app runs but consistently crashes
I’ve got to the end of Ch. 11, and the app runs, with all tabs displaying what they should – at first. After switching around between Standings, Players, Leaders, etc., the app always eventually has problems reloading, for instance, Standings. Then, I’ll try to load Leaders, and it crashes with this error (as far as I can tell, it’s always mentioning the LeadersListFragment). Is this due to the “experimental” status of some of the packages imported, or is it something else? It happens on both my Samsung tablet and on the virtual Pixel 3a.
FATAL EXCEPTION: main
Process: com.example.abl, PID: 13592
androidx.fragment.app.Fragment$InstantiationException: Unable to instantiate fragment com.example.abl.leaders.LeadersListFragment: could not find Fragment constructor
at androidx.fragment.app.Fragment.instantiate(Fragment.java:687)
at androidx.fragment.app.FragmentContainer.instantiate(FragmentContainer.java:57)
at androidx.fragment.app.FragmentManager$3.instantiate(FragmentManager.java:525)
at androidx.fragment.app.FragmentState.instantiate(FragmentState.java:84)
at androidx.fragment.app.FragmentStateManager.<init>(FragmentStateManager.java:91)
at androidx.fragment.app.FragmentManager.restoreSaveStateInternal(FragmentManager.java:2562)
at androidx.fragment.app.Fragment.restoreChildFragmentState(Fragment.java:1988)
at androidx.fragment.app.Fragment.onCreate(Fragment.java:1967)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:3094)
at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:504)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:268)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1943)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1845)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1782)
at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:565)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:246)
at android.app.ActivityThread.main(ActivityThread.java:8653)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)
Caused by: java.lang.NoSuchMethodException: com.example.abl.leaders.LeadersListFragment.<init> []
at java.lang.Class.getConstructor0(Class.java:2332)
at java.lang.Class.getConstructor(Class.java:1728)
at androidx.fragment.app.Fragment.instantiate(Fragment.java:672)
at androidx.fragment.app.FragmentContainer.instantiate(FragmentContainer.java:57)
at androidx.fragment.app.FragmentManager$3.instantiate(FragmentManager.java:525)
at androidx.fragment.app.FragmentState.instantiate(FragmentState.java:84)
at androidx.fragment.app.FragmentStateManager.<init>(FragmentStateManager.java:91)
at androidx.fragment.app.FragmentManager.restoreSaveStateInternal(FragmentManager.java:2562)
at androidx.fragment.app.Fragment.restoreChildFragmentState(Fragment.java:1988)
at androidx.fragment.app.Fragment.onCreate(Fragment.java:1967)
at androidx.fragment.app.Fragment.performCreate(Fragment.java:3094)
at androidx.fragment.app.FragmentStateManager.create(FragmentStateManager.java:504)
at androidx.fragment.app.FragmentStateManager.moveToExpectedState(FragmentStateManager.java:268)
at androidx.fragment.app.FragmentManager.executeOpsTogether(FragmentManager.java:1943)
at androidx.fragment.app.FragmentManager.removeRedundantOperationsAndExecute(FragmentManager.java:1845)
at androidx.fragment.app.FragmentManager.execPendingActions(FragmentManager.java:1782)
at androidx.fragment.app.FragmentManager$5.run(FragmentManager.java:565)
at android.os.Handler.handleCallback(Handler.java:938)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:246)
at android.app.ActivityThread.main(ActivityThread.java:8653)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)
2023-12-06 14:58:29.915 13592-13592 Process com.example.abl I Sending signal. PID: 13592 SIG: 9
Marked As Solved
mfazio23
Author of Kotlin and Android Development featuring Jetpack
Alright, this took me a bit since my original app still works as written, so I’m thinking this is due to a change in one of the navigation library. It’s seems like it’s trying to be helpful and re-create your Fragment automatically, but since it doesn’t know the leaderType it can’t.
I’d say the proper approach here is to send the leaderType as an argument to the LeadersListFragment rather than as a constructor parameter:
val leaderType = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
arguments?.getSerializable(LEADER_TYPE_KEY, LeaderType::class.java)
} else {
arguments?.getSerializable(LEADER_TYPE_KEY) as? LeaderType
} ?: LeaderType.Batting
You can then remove leaderType from the constructor. Note that the extra version check logic is due to arguments?.getSerializable(LEADER_TYPE_KEY) being deprecated for API level 33, but our app supports lower versions.
You can also do this the easy way and make the constructor parameter nullable:
class LeadersListFragment(private val leaderType: LeaderType? = LeaderType.Batting)
Sorry this took a bit for me to get back to you!
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