jason flanagan jason flanagan - 5 months ago 16
Android Question

How do I setup a customListView in android?

I have been following a tutorial but I think it is out of date, I have setup everything I think I need for the listView to work but when I run it, it says -

java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
at youknow.smscontrol.jason.testexpandiblelistview.CoustmListViewSettup.getView(CoustmListViewSettup.java:29)


Here's my XML:


<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Medium Text"
android:textColor="@android:color/white"
android:id="@+id/CMDnameItem"
android:padding="10dp"
android:layout_alignParentTop="true"
android:layout_alignParentStart="true"/>

<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/item_launch"
android:id="@+id/LaunchArrow"
android:layout_alignBottom="@+id/CMDnameItem"
android:layout_alignParentEnd="true"
android:layout_alignTop="@+id/CMDnameItem"/>



Here is my main code:

public void SettupIds(){
listView = (ListView) findViewById(R.id.listView);
}

public void SetupAndDisplayListView(){
String[] CMDlist = {"Launch App Settings", "Alarm Settings", "Lock Screen Settings", "Display Message Settings", "Take Picture Settings"};
ListAdapter CMDlistAdapter = new CustomListViewSetup(getApplicationContext(), CMDlist);
listView.setAdapter(CMDlistAdapter);
}


Here is my customListViewSetup class:

class CustomListViewSetup extends ArrayAdapter<String>{

public CustomListViewSetup(Context context, String[] CMDList){
super(context,R.layout.coustom_list_item ,CMDList);
}

@Override
public View getView(int position, View convertView, ViewGroup parent){

LayoutInflater CMDlistInflater = LayoutInflater.from(getContext());
View coustomView = CMDlistInflater.inflate(R.layout.coustom_list_item, parent, false);

String CurrentCMDlistitem = getItem(position);
LINE 29>> TextView CMDlist = (TextView) convertView.findViewById(R.id.CMDnameItem);
ImageView CMDLaunchArrow = (ImageView) convertView.findViewById(R.id.LaunchArrow);

CMDlist.setText(CurrentCMDlistitem);
CMDLaunchArrow.setBackgroundResource(R.drawable.item_launch);




return coustomView;
}
}


thank you in advance!

Answer

Replace the lines

 TextView CMDlist = (TextView) convertView.findViewById(R.id.CMDnameItem);
ImageView CMDLaunchArrow = (ImageView) convertView.findViewById(R.id.LaunchArrow);

by

 TextView CMDlist = (TextView) coustomView.findViewById(R.id.CMDnameItem);
    ImageView CMDLaunchArrow = (ImageView) coustomView.findViewById(R.id.LaunchArrow);
Comments