setLayoutManager on a null object referent in RecycleView

Question

I am trying to display restaurant by RecyclerView. when I set layoutManager, I do not know reason why LinearLayoutManager is null. Here my code

activity_home.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/app_bar_home">

    <ss.com.bannerslider.Slider
        android:id="@+id/banner_slider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

   <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recycle_restaurant"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

HomeActivity.java

@BindView(R.id.banner_slider)
Slider banner_slider;
@BindView(R.id.recycle_restaurant)
RecyclerView recycle_restaurant;
...
ButterKnife.bind(this);
...
LinearLayoutManager layoutManager = new LinearLayoutManager(this);
recycle_restaurant.setLayoutManager(layoutManager);
recycle_restaurant.addItemDecoration(new DividerItemDecoration(this, 
layoutManager.getOrientation()));

error

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setLayoutManager(androidx.recyclerview.widget.RecyclerView$LayoutManager)' on a null object reference
        at com.huyvt.restaurant.HomeActivity.initView(HomeActivity.java:105)
        at com.huyvt.restaurant.HomeActivity.onCreate(HomeActivity.java:81)
        at android.app.Activity.performCreate(Activity.java:6845)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2700)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2808) 
        at android.app.ActivityThread.-wrap12(ActivityThread.java) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1541) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:165) 
        at android.app.ActivityThread.main(ActivityThread.java:6375) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:912) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:802)

Help me fix it!

Does this answer your question? [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) — Ehsan msz, Jun 11 '20 at 14:00

score 0 · Accepted Answer · answered Jun 11 '20 at 16:18

Just add app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" to your RecyclerView tag in your XML. Like this:

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recycle_restaurant"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

Hope it works for you!

setLayoutManager on a null object referent in RecycleView

1 Answers1