How to use Baseadapter in a listview?Why i am getting Null point exception?

Question

I tried to insert elements into a listview using baseadapter.I want to insert the menu into the listview.I have used an adapter-DatasetAdapter to inflate row into the listview,but i am getting null pointer exception at this line-row = inflater.inflate(R.layout.menu_detail, parent,false);

DatasetAdapter adapter=new DatasetAdapter(this,menu);
        dList.setAdapter(adapter);
menu = new String[]{"Feedback","Help","Tour","Sign in/Sign up"};

DataSetAdapter.java

public class DatasetAdapter extends BaseAdapter  {


private Context context;
private String[] menuitems;

LayoutInflater inflater;

public DatasetAdapter(Context cont, String[] menu) {
    this.context=cont;
    this.menuitems=menu;

}

@Override
public int getCount() {
    // TODO Auto-generated method stub

    return menuitems.length;
}

@Override
public Object getItem(int position) {
    // TODO Auto-generated method stub
    return null;
}

@Override
public long getItemId(int arg0) {
    // TODO Auto-generated method stub
    return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    // TODO Auto-generated method stub
    View row = convertView;

    if (row == null)
        row = inflater.inflate(R.layout.menu_detail, parent,false);

    TextView titlerow = (TextView) row.findViewById(R.id.detail);

    return row;
}


}

menu_detail.java

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:gravity="center"
    android:background="#5ba4e5"
    android:layout_height="match_parent">
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="8pt"
        android:textColor="#000000"
        android:layout_gravity="center"
        android:id="@+id/detail"/>

</LinearLayout>

Answer 1

you are getting NullPointerException because menuitems is null when getCount is invoked. Change

DatasetAdapter adapter=new DatasetAdapter(this,menu);
dList.setAdapter(adapter);
menu = new String[]{"Feedback","Help","Tour","Sign in/Sign up"};

to

menu = new String[]{"Feedback","Help","Tour","Sign in/Sign up"};
DatasetAdapter adapter=new DatasetAdapter(this,menu);
dList.setAdapter(adapter);

your getItem should return the item at position. You are not using it right now, but you will probably use it int the future:

@Override
public Object getItem(int position) {    
    return menuitems[position];
}

in your constructor you never initialize inflater

public DatasetAdapter(Context cont, String[] menu) {
    this.context=cont;
    this.menuitems=menu;
    inflater = LayoutInflater.from(cont);
}

and you can avoid to keep a reference to the context since you are not using it anywhere