java.lang.IllegalArgumentException：指定为非空的参数是 null：- android，应用程序启动但立即崩溃

Question

Hey guys I have problem with starting my app, I don't know what is the problem, it just crashes right away when I start it, from the log I suppose it is something about databinding but I don't really know what's wrong right now:C

2020-04-10 22:22:22.716 32624-32624/? I/rss.ing_projec: Late-enabling -Xcheck:jni
2020-04-10 22:22:22.746 32624-32624/? E/rss.ing_projec: Unknown bits set in runtime_flags: 0x8000
2020-04-10 22:22:23.053 32624-32624/com.lswarss.ing_project I/Perf: Connecting to perf service.
2020-04-10 22:22:23.070 32624-32624/com.lswarss.ing_project V/Font: Change font:1
2020-04-10 22:22:23.071 32624-32624/com.lswarss.ing_project V/Font: Default family:android.graphics.Typeface@177a2b82
2020-04-10 22:22:23.077 32624-32676/com.lswarss.ing_project E/Perf: Fail to get file list com.lswarss.ing_project
2020-04-10 22:22:23.077 32624-32676/com.lswarss.ing_project E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2020-04-10 22:22:23.077 32624-32676/com.lswarss.ing_project E/Perf: Fail to get file list com.lswarss.ing_project
2020-04-10 22:22:23.078 32624-32676/com.lswarss.ing_project E/Perf: getFolderSize() : Exception_1 = java.lang.NullPointerException: Attempt to get length of null array
2020-04-10 22:22:23.156 32624-32624/com.lswarss.ing_project W/rss.ing_projec: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
2020-04-10 22:22:23.157 32624-32624/com.lswarss.ing_project W/rss.ing_projec: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
2020-04-10 22:22:23.213 32624-32624/com.lswarss.ing_project V/FlingOptimizerScroller: FlingOptimizerOverScroller Init
2020-04-10 22:22:23.251 32624-32624/com.lswarss.ing_project D/AndroidRuntime: Shutting down VM
2020-04-10 22:22:23.253 32624-32624/com.lswarss.ing_project E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.lswarss.ing_project, PID: 32624
    java.lang.RuntimeException: Failed to call observer method
        at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:226)
        at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeMethodsForEvent(ClassesInfoCache.java:194)
        at androidx.lifecycle.ClassesInfoCache$CallbackInfo.invokeCallbacks(ClassesInfoCache.java:185)
        at androidx.lifecycle.ReflectiveGenericLifecycleObserver.onStateChanged(ReflectiveGenericLifecycleObserver.java:37)
        at androidx.lifecycle.LifecycleRegistry$ObserverWithState.dispatchEvent(LifecycleRegistry.java:361)
        at androidx.lifecycle.LifecycleRegistry.forwardPass(LifecycleRegistry.java:300)
        at androidx.lifecycle.LifecycleRegistry.sync(LifecycleRegistry.java:339)
        at androidx.lifecycle.LifecycleRegistry.moveToState(LifecycleRegistry.java:145)
        at androidx.lifecycle.LifecycleRegistry.handleLifecycleEvent(LifecycleRegistry.java:131)
        at androidx.fragment.app.Fragment.performStart(Fragment.java:2735)
        at androidx.fragment.app.FragmentStateManager.start(FragmentStateManager.java:365)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1194)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1356)
        at androidx.fragment.app.FragmentManager.moveFragmentToExpectedState(FragmentManager.java:1434)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1497)
        at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2625)
        at androidx.fragment.app.FragmentManager.dispatchStart(FragmentManager.java:2583)
        at androidx.fragment.app.Fragment.performStart(Fragment.java:2739)
        at androidx.fragment.app.FragmentStateManager.start(FragmentStateManager.java:365)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1194)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1356)
        at androidx.fragment.app.FragmentManager.moveFragmentToExpectedState(FragmentManager.java:1434)
        at androidx.fragment.app.FragmentManager.moveToState(FragmentManager.java:1497)
        at androidx.fragment.app.FragmentManager.dispatchStateChange(FragmentManager.java:2625)
        at androidx.fragment.app.FragmentManager.dispatchStart(FragmentManager.java:2583)
        at androidx.fragment.app.FragmentController.dispatchStart(FragmentController.java:258)
        at androidx.fragment.app.FragmentActivity.onStart(FragmentActivity.java:550)
        at androidx.appcompat.app.AppCompatActivity.onStart(AppCompatActivity.java:201)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1514)
        at android.app.Activity.performStart(Activity.java:7838)
        at android.app.ActivityThread.handleStartActivity(ActivityThread.java:3398)
        at android.app.servertransaction.TransactionExecutor.performLifecycleSequence(TransactionExecutor.java:221)
        at android.app.servertransaction.TransactionExecutor.cycleToPath(TransactionExecutor.java:201)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:173)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2109)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7682)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)
     Caused by: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter data
        at com.lswarss.ing_project.adapters.BindingAdaptersKt.bindRecyclerView(Unknown Source:7)
        at com.lswarss.ing_project.databinding.PostsFragmentBindingImpl.executeBindings(PostsFragmentBindingImpl.java:125)
2020-04-10 22:22:23.253 32624-32624/com.lswarss.ing_project E/AndroidRuntime:     at androidx.databinding.ViewDataBinding.executeBindingsInternal(ViewDataBinding.java:473)
        at androidx.databinding.ViewDataBinding.executePendingBindings(ViewDataBinding.java:445)
        at androidx.databinding.ViewDataBinding$OnStartListener.onStart(ViewDataBinding.java:1687)
        at java.lang.reflect.Method.invoke(Native Method)
        at androidx.lifecycle.ClassesInfoCache$MethodReference.invokeCallback(ClassesInfoCache.java:216)
            ... 41 more

That's the log given by android studio And it have some problems with this class but what wrong with it:

package com.lswarss.ing_project.adapters

import android.view.View
import android.widget.ImageView
import androidx.databinding.BindingAdapter
import androidx.recyclerview.widget.RecyclerView
import com.lswarss.ing_project.R
import com.lswarss.ing_project.domain.PostItem
import com.lswarss.ing_project.fragments.PostsApiStatus

@BindingAdapter("listData")
fun bindRecyclerView(recyclerView: RecyclerView, data: List<PostItem>?){
    val adapter  = recyclerView.adapter as PostsAdapter
    adapter.submitList(data)
}


@BindingAdapter("postApiStatus")
fun bindStatus(statusImageView: ImageView, status: PostsApiStatus?) {
    when (status) {
        PostsApiStatus.LOADING -> {
            statusImageView.visibility = View.VISIBLE
            statusImageView.setImageResource(R.drawable.loading_animation)
        }
        PostsApiStatus.ERROR -> {
            statusImageView.visibility = View.VISIBLE
            statusImageView.setImageResource(R.drawable.ic_connection_error)
        }
        PostsApiStatus.DONE -> {
            statusImageView.visibility = View.GONE
        }
    }
}

I was trying to do this application using the app made in udacity course Mars Real Estate App

Here is link to my app on github: https://github.com/LSWarss/ing_project The code I have problems with is on branch new_architecture

Sory if this is stupid question but I'm new to android and koltlin, or even posting on stack:)

Answer 1

   Caused by: java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter data
   at com.lswarss.ing_project.adapters.BindingAdaptersKt.bindRecyclerView(Unknown Source:7

This is happening because as long as I saw from github, in your PostsFragment you are not setting the adapter to the recycler view, so it's null when the binding adapter is trying to access it.

Also, I noticed this in your master branch:

viewModel.posts.observe(viewLifecycleOwner, Observer {
    posts -> recycler_view_posts.also{
    it.layoutManager = LinearLayoutManager(requireContext())
    it.setHasFixedSize(true)
    it.adapter = PostsAdapter(posts)
}

You don't have to initialize your recycler view each time you get something on observe.

In onViewCreated() method from fragment you can set the adapter and the layoutManager (and this will also solve your error if you add it in PostsFragment):

private fun initRecyclerView(){
    recycler_view_posts.run{
        adapter = PostsAdapter(posts)
        layoutManager = LinearLayoutManager(requireContext())
        setHasFixedSize(true)
    }
}

and then on observe you only have to refresh the content with the approach from new_architecture branch ( adapter.submitList(list) ) or by setting the new list in adapter and calling adapter.notifyDataSetChange() .

Answer 2

change bindRecyclerView to this:

@BindingAdapter("listData")
fun bindRecyclerView(recyclerView: RecyclerView, data: List<PostItem>?){
    val adapter  = recyclerView.adapter as PostsAdapter? // changed to nullable type
    adapter?.submitList(data)// nullablity checked
}