Attempt to invoke interface method 'java.lang.Object java.util.List.get(int)

Question

I am developing new and I am reading JSON file from asset folder but I am getting the following exception

java.lang.NullPointerException: Attempt to invoke interface method 'java.lang.Object java.util.List.get(int)' on a null object reference
    at yodgorbek.komilov.runtastictask1.CustomAdapter.getView(CustomAdapter.kt:45)
    at android.widget.AbsListView.obtainView(AbsListView.java:2365)
    at android.widget.ListView.makeAndAddView(ListView.java:2052)
    at android.widget.ListView.fillDown(ListView.java:786)
    at android.widget.ListView.fillFromTop(ListView.java:847)
    at android.widget.ListView.layoutChildren(ListView.java:1826)
    at android.widget.AbsListView.onLayout(AbsListView.java:2164)
    at android.view.View.layout(View.java:19828)
    at android.view.ViewGroup.layout(ViewGroup.java:6154)
    at androidx.constraintlayout.widget.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
    at android.view.View.layout(View.java:19828)
    at android.view.ViewGroup.layout(ViewGroup.java:6154)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:19828)
    at android.view.ViewGroup.layout(ViewGroup.java:6154)
    at androidx.appcompat.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:446)
    at android.view.View.layout(View.java:19828)
    at android.view.ViewGroup.layout(ViewGroup.java:6154)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at android.view.View.layout(View.java:19828)
    at android.view.ViewGroup.layout(ViewGroup.java:6154)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1791)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1635)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1544)
    at android.view.View.layout(View.java:19828)
    at android.view.ViewGroup.layout(ViewGroup.java:6154)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
    at com.android.internal.policy.DecorView.onLayout(DecorView.java:765)
    at android.view.View.layout(View.java:19828)
    at android.view.ViewGroup.layout(ViewGroup.java:6154)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2643)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2348)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1482)
    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7124)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:1008)
    at android.view.Choreographer.doCallbacks(Choreographer.java:804)
    at android.view.Choreographer.doFrame(Choreographer.java:732)
    at android.view.Choreographer$FrameHandler.handleMessage(Choreographer.java:907)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:176)
    at android.app.ActivityThread.main(ActivityThread.java:6662)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

below my code to gist

possible duplicate https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it — SebastienRieu, Oct 21 '19 at 12:49
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Ashish, Oct 21 '19 at 12:50
@FurqanKhan My code very long thats why I have posted gistlist please check it stackoverflow did not allowed to post all thats why I shared as gist — Edgar, Oct 21 '19 at 12:53
@sashabeliy check `model` value is it null? `val model = gson.fromJson(loadJSONFromAssets(), NetworkResponse::class.java)` — Basi, Oct 21 '19 at 12:55

score 1 · Answer 1 · answered Oct 21 '19 at 12:56

1

You are using a wrong key for members in your Group data class, it is data while in your json it shows the key is members use the following class and it will work

data class Group(
    @SerializedName("group_id")
    val group_id: Int,

    @SerializedName("group_name")
    val group_name: String,

    @SerializedName("members")
    val members: List<Member>

)

answered Oct 21 '19 at 12:56

Furqan Khan

528
4
14

it is showing empty white screen what is your suggestion – Edgar Oct 21 '19 at 13:02
because in your main activity xml you have not assinged the constraints to list view, i would recommend to change constraint layout to linear layout – Furqan Khan Oct 21 '19 at 13:05
it is still the same i have changed to linearlayout vertical – Edgar Oct 21 '19 at 13:19
what do you think main problem – Edgar Oct 21 '19 at 13:22

score 0 · Answer 2 · answered Oct 21 '19 at 12:58

0

You are not using correct key

data class Group(
@SerializedName("group_id")
val group_id: Int,

@SerializedName("group_name")
val group_name: String,

@SerializedName("data")
val members: List<Member>)

According to your json schema it should be

data class Group(
@SerializedName("group_id")
val group_id: Int,

@SerializedName("group_name")
val group_name: String,

@SerializedName("members")
val members: List<Member>)

answered Oct 21 '19 at 12:58

Amit Tiwary

787
1
8
16

it did not help – Edgar Oct 21 '19 at 13:21
App is still crashing or some other error is coming? – Amit Tiwary Oct 21 '19 at 13:25

Attempt to invoke interface method 'java.lang.Object java.util.List.get(int)

2 Answers2