ListView has force close

Question

I am beginner in android and I want to learn working with ListView. I have searched for that and tried to make a List View.

But unfortunately It has force close at the beginning.

here is activity_main.xml:

<ListView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent" 
android:id="@+id/List"/>

here is list_row.xml:

<?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="wrap_content" 
android:orientation="vertical"> 

    <TextView android:id="@+id/groupTitle"   
    android:layout_width="fill_parent"   
    android:layout_height="wrap_content"  
    android:textSize="12dp" />

</LinearLayout>

here is CustomListView.java:

public class CustomListView extends BaseAdapter{

    private ArrayList<ItemClass> arr = new ArrayList<ItemClass>(); 

    public CustomListView( ArrayList<ItemClass> arr) {
        this.arr = arr;
    }

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

    @Override
    public Object getItem(int index) {
        return getItem(index);
    }

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

    @Override
    public View getView(int index, View view, ViewGroup parent) {

        if(view == null)
        {
            LayoutInflater inflator = LayoutInflater.from(parent.getContext());
            view = inflator.inflate(R.layout.list_row, parent, false);
        }

        ItemClass child = arr.get(index);
        TextView Text = (TextView)  view.findViewById(R.id.groupTitle);
        Text.setText(child.getName());
        return null;
    }

}

here is main class:

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ArrayList<ItemClass> arr = new ArrayList<ItemClass>();
        arr.add(new ItemClass("Sh " , 1));
        CustomListView adaptor;
        adaptor = new CustomListView(arr);

        ListView listView = (ListView) findViewById(R.id.List);

        listView.setAdapter(adaptor);
    }
}

and finally here is ItemClass.java:

public class ItemClass {

    //private Context context;
    String name;
    private int rate;

    public ItemClass(String name , int rate ) {
        this.setName(name);
        this.setRate(rate);
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getName() {
        return this.name;
    }

    public void setRate(int rate) {
        this.rate = rate;
    }

    public int getRate() {
        return this.rate;
    }
}

I have commented listView.setAdapter(adaptor); then it had no force close.

can anyone help me??

Thanks in advance for your attention

Answer 1

You need to change your getItem method in your adapter class as below :

@Override
public Object getItem(int index) {
    return arr.get(index);
}

Also change your getView method to return the custom view besides null as below:

@Override
public View getView(int index, View view, ViewGroup parent) {

    if(view == null)
    {
        LayoutInflater inflator = LayoutInflater.from(parent.getContext());
        view = inflator.inflate(R.layout.list_row, parent, false);
    }
  //.............................
    return view;
}

Answer 2

First you correct this you should return a view

 return view;

instead of

 return null;

in getView(....) method in your Adapter

Answer 3

public class ListViewAdapter extends BaseAdapter{
    private ArrayList<String> listname;
    private ArrayList<Integer> listimg;
    private ArrayList<String> listtype;
    private Activity activity;
    public ListViewAdapter(Activity act,ArrayList<String> liststr,ArrayList<Integer> listint,ArrayList<String> list_type)
    {


        super();
        this.listname=new ArrayList<String>();
        this.listname=liststr;
        this.listimg=listint;
        this.listtype=list_type;
        this.activity=act;
        System.out.println("this is contry name "+this.listname);
        System.out.println("this is img  name  "+this.listimg);
        System.out.println("this is type   "+this.listtype);
    }


    @Override
    public int getCount() {
        // TODO Auto-generated method stub
        System.out.println("len " + listname.size());
        return listname.size();
    }

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

    @Override
    public long getItemId(int arg0) {
        // TODO Auto-generated method stub
        return 0;
    }
    public static class ViewHolder {
        public ImageView imgViewFlag;
        public TextView txtViewTitle;
        public TextView txtViewType;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        // TODO Auto-generated method stub
        ViewHolder view;
        LayoutInflater inflator = activity.getLayoutInflater();

        if (convertView == null) {
            view = new ViewHolder();
            convertView = inflator.inflate(R.layout.notes_listlayout, null);

            view.txtViewTitle = (TextView) convertView
                    .findViewById(R.id.note_layout_name);

            //view.txtViewTitle.setText("NO Notes Available.");
            view.txtViewType= (TextView) convertView
                    .findViewById(R.id.note_layout_type);
            view.txtViewType.setTypeface(Typeface.createFromAsset(parent
                    .getContext().getAssets(), "fonts/DroidSerif.ttf"));
            view.txtViewTitle.setTypeface(Typeface.createFromAsset(parent
                    .getContext().getAssets(), "fonts/DroidSerif.ttf"));
        //  view.txtViewTitle.setTextColor(Color.BLACK);
            //view.txtViewType.setTextColor(Color.GRAY);
            /*TextView emptyView = (TextView)findViewById(R.id.emptyTv);
            view.setEmptyView(yourEmptyView);*/
            view.imgViewFlag = (ImageView) convertView
                    .findViewById(R.id.note_layout_img);

        //  view.imgViewFlag.setBackgroundResource(R.drawable.view_default);
            convertView.setTag(view);
        } 



        else {
            view = (ViewHolder) convertView.getTag();
        }
        System.gc();
        try {
            view.txtViewTitle.setText(listname.get(position));
            view.txtViewType.setText(listtype.get(position));
            view.imgViewFlag.setImageResource(listimg.get(position));

        } catch (Exception e) {
            //System.out.println("this is error " + e.getMessage());
        }

        return convertView;
    }

}

to implement it

ListViewAdapter mAdapter;
mAdapter = new ListViewAdapter(this, listCountry, listFlag,
                listfoodtype);
        lv_note = (ListView) findViewById(R.id.lv_note);
        // gridView.setBackgroundColor(Color.WHITE);

        lv_note.setAdapter(mAdapter);