I'm trying to populate a RecyclerView with movie posters, however the app keeps crashing. Giving me this error:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
I have looked at all the similar threads and tried everyones suggestions but it still wont work.
Here is my code where the error is:
//I get the error on this line
MoviesRV.setAdapter(movieAdapter);
//I set the layout which some people said may cause the error.
MoviesRV.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
Here's my MovieAdapter class
package com.example.myapplication1
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import java.util.List;
public class MovieAdapter extends RecyclerView.Adapter<MovieAdapter.MyViewHolder> {
Context context ;
List<Movie> mData;
public MovieAdapter(Context context, List<Movie> mData) {
this.context = context;
this.mData = mData;
}
@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {
View view = LayoutInflater.from(context).inflate(R.layout.content_movie,viewGroup,false);
return new MyViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, int i) {
myViewHolder.TvTitle.setText(mData.get(i).getTitle());
myViewHolder.ImgMovie.setImageResource(mData.get(i).getThumbnail());
}
@Override
public int getItemCount() {
return mData.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
private TextView TvTitle;
private ImageView ImgMovie;
public MyViewHolder(@NonNull View itemView) {
super(itemView);
TvTitle = itemView.findViewById(R.id.movie_id);
ImgMovie = itemView.findViewById(R.id.movie_poster);
}
}
}
MainActivity.Java
package com.example.myapplication1;
import android.os.Bundle;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
import android.view.View;
import androidx.navigation.NavController;
import androidx.navigation.Navigation;
import androidx.navigation.ui.AppBarConfiguration;
import androidx.navigation.ui.NavigationUI;
import com.google.android.material.navigation.NavigationView;
import androidx.drawerlayout.widget.DrawerLayout;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.view.Menu;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private AppBarConfiguration mAppBarConfiguration;
private RecyclerView MoviesRV;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MoviesRV = findViewById(R.id.RV_Posters);
Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = findViewById(R.id.drawer_layout);
NavigationView navigationView = findViewById(R.id.nav_view);
// Passing each menu ID as a set of Ids because each
// menu should be considered as top level destinations.
mAppBarConfiguration = new AppBarConfiguration.Builder(
R.id.nav_home, R.id.nav_watching, R.id.nav_settings,
R.id.nav_contact, R.id.nav_share)
.setDrawerLayout(drawer)
.build();
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
NavigationUI.setupWithNavController(navigationView, navController);
List<Movie> movies1 = new ArrayList<>();
movies1.add(new Movie("Yu-Gi-Oh! The Movie", R.drawable.yugiohthemovie));
MovieAdapter movieAdapter = new MovieAdapter(this, movies1);
MoviesRV.setAdapter(movieAdapter);
MoviesRV.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onSupportNavigateUp() {
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
return NavigationUI.navigateUp(navController, mAppBarConfiguration)
|| super.onSupportNavigateUp();
}
}
Here is my logcat and HomeFragment
2019-08-22 20:34:43.899 10976-10976/com.example.webtoons E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.webtoons, PID: 10976
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.webtoons/com.example.webtoons.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2778)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.recyclerview.widget.RecyclerView.setAdapter(androidx.recyclerview.widget.RecyclerView$Adapter)' on a null object reference
at com.example.webtoons.MainActivity.onCreate(MainActivity.java:61)
at android.app.Activity.performCreate(Activity.java:7009)
at android.app.Activity.performCreate(Activity.java:7000)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1214)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2731)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856)
at android.app.ActivityThread.-wrap11(Unknown Source:0)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589)
at android.os.Handler.dispatchMessage(Handler.java:106)
at android.os.Looper.loop(Looper.java:164)
at android.app.ActivityThread.main(ActivityThread.java:6494)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)
HomeFragment
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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">
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/RV_Posters"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="52dp"
android:layout_marginBottom="489dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.228"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
