ANDROID adapter - NullPointerException at getView method (line : textView.setText())

Question

I have a NPE when coding my android application. I already read at least hundreds of topics about it without finding any answer. So I finally ask directly there. Here is the error :

01-19 21:13:09.886: E/AndroidRuntime(6622): FATAL EXCEPTION: main
01-19 21:13:09.886: E/AndroidRuntime(6622): java.lang.NullPointerException
01-19 21:13:09.886: E/AndroidRuntime(6622):     at esstin.projet.ExpositionAdaptateur.getView(ExpositionAdaptateur.java:59)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.AbsListView.obtainView(AbsListView.java:2465)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.ListView.measureHeightOfChildren(ListView.java:1250)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.ListView.onMeasure(ListView.java:1162)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.View.measure(View.java:15504)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5059)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1396)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.View.measure(View.java:15504)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5059)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.View.measure(View.java:15504)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5059)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1396)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.View.measure(View.java:15504)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5059)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2385)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.View.measure(View.java:15504)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1979)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1222)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1395)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1115)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4526)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.Choreographer.doCallbacks(Choreographer.java:555)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.Choreographer.doFrame(Choreographer.java:525)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.os.Handler.handleCallback(Handler.java:615)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.os.Handler.dispatchMessage(Handler.java:92)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.os.Looper.loop(Looper.java:137)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at android.app.ActivityThread.main(ActivityThread.java:4921)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at java.lang.reflect.Method.invokeNative(Native Method)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at java.lang.reflect.Method.invoke(Method.java:511)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
01-19 21:13:09.886: E/AndroidRuntime(6622):     at dalvik.system.NativeStart.main(Native Method)

Then the class "ExpositionAdaptateur" which is the custom adapter (error at the line with "nomExpo.setText(listeExpo.get(position).getNom());" :

package esstin.projet;

import java.util.List;

import esstin.projet.accesbase.Exposition;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.LinearLayout;
import android.widget.TextView;

public class ExpositionAdaptateur extends BaseAdapter {

    List<Exposition> listeExpo;
    LayoutInflater inflater;
    Context context;

    public ExpositionAdaptateur(Context context, List<Exposition> listeExpo) {
        //inflater = LayoutInflater.from(context);
        inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        this.listeExpo = listeExpo;
        this.context = context;
    }

    @Override
    public int getCount() {
        return listeExpo.size();
    }

    @Override
    public Object getItem(int position) {
        return listeExpo.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
          LinearLayout layoutItem;
          //(1) : Réutilisation des layouts
          if (convertView == null) {
            //Initialisation de notre item à partir du  layout XML "personne_layout.xml"
            layoutItem = (LinearLayout) inflater.inflate(R.layout.expositionadaptateur, parent, false);
          } else {
            layoutItem = (LinearLayout) convertView;
          }

          //(2) : Récupération des TextView de notre layout      
          TextView nomExpo = (TextView)layoutItem.findViewById(R.id.nomExpo);

          //(3) : Renseignement des valeurs       
          nomExpo.setText(listeExpo.get(position).toString());

          //On retourne l'item créé.
          return layoutItem;
        }

}

This is the layout for each line of my ListView :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

    <TextView
        android:id="@+id/nomExpo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </TextView>

</LinearLayout>

Then the main layout :

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <ListView
        android:id="@+id/listViewExpo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" >
    </ListView>

</LinearLayout>

Finally the main class :

package esstin.projet;

import java.util.ArrayList;
import java.util.List;

import esstin.projet.accesbase.Exposition;
import esstin.projet.accesbase.ExpositionBDD;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

public class AccueilGalerie_activity extends Activity implements View.OnClickListener {

    private Button boutonExpo1 = null;
    private Button boutonExpo2 = null;
    private Button boutonExpo3 = null;
    private TextView expo1TxtView = null;
    List<Exposition> listeExposition = new ArrayList<Exposition>();
    ListView listViewExpo;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.accueilgalerie_activity);
        int count = 0;
        ExpositionBDD expoBdd = new ExpositionBDD(this);
        expoBdd.open();

        while(count <= expoBdd.getNumberOfRows()){
            Exposition expoFromDb = expoBdd.getExpositionWithId(count);
            listeExposition.add(expoFromDb);
            count++;
        }

        expoBdd.close();
        ExpositionAdaptateur adapter = new ExpositionAdaptateur(this,listeExposition);
        listViewExpo = (ListView)findViewById(R.id.listViewExpo);
        listViewExpo.setAdapter(adapter);

    }

    @Override
    public void onClick(View v) {

    }

}

I'm trying to fix it since a week, so that would be great if someone could find what's happening :) !

Thanks !

Answer 1

int count = 0;
//...
while(count <= expoBdd.getNumberOfRows()){
    Exposition expoFromDb = expoBdd.getExpositionWithId(count);
    listeExposition.add(expoFromDb);
    count++;
}

This loop runs getNumberOfRows() + 1 times. Now, depending on getExpositionWithId() implementation, it may result in a null to end up in the list, causing a NPE when toString() is called on it here:

nomExpo.setText(listeExpo.get(position).toString());

Quick fix: change the <= to <.