create listview with alphabetic separators android - how?

Question

I have the following code. I need to create list separators before A elements, B and so on. I need to have someting like this: A Ana Al...B Bob Bill...C Cane Cod...Z Zane. How to impove my code? need some help. I am new to android and I really don't know how to solve this.

main.xml

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

<ListView
        android:id="@+id/myListView"
        android:fastScrollEnabled="true"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:fadeScrollbars="true"
        android:scrollbarSize="100dp"
        android:scrollbarStyle="insideOverlay"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" />  


</RelativeLayout>

item1.xml

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

<ListView
        android:id="@+id/myListView"
        android:fastScrollEnabled="true"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:fadeScrollbars="true"
        android:scrollbarSize="100dp"
        android:scrollbarStyle="insideOverlay"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" />  

<TextView
android:id="@+id/textSeparator"
android:layout_height="wrap_content" 
android:gravity="center" 
android:text="text" 
android:visibility="visible" 
 android:layout_width="fill_parent" 
android:textColor="#FFFFFFFF" 
android:background="#FFFF0000" />

</RelativeLayout>

.java

package scroll.packet;


    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.HashMap;
    import java.util.Iterator;
    import java.util.List;
    import java.util.Random;
    import java.util.Set;

    import android.app.Activity;
    import android.content.Context;
    import android.os.Bundle;
    import android.util.Log;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;
    import android.widget.SectionIndexer;

    public class FastScrollActivity extends Activity {
            ListView myListView;
            ArrayList<String> elements;

            @Override
            public void onCreate(Bundle savedInstanceState) {
                    super.onCreate(savedInstanceState);
                    setContentView(R.layout.main);

                    // elements
                    String s = "QWERTZUIOPASDFGHJKLYXCVBNM";
                    Random r = new Random();
                    elements = new ArrayList<String>();
                    for (int i = 0; i < 300; i++) {

                            elements.add(s.substring(r.nextInt(s.length())));

                    }
                    Collections.sort(elements); // Must be sorted!

                    // listview
                    myListView = (ListView) findViewById(R.id.myListView);
                    myListView.setFastScrollEnabled(true);


                    //myListView.
                    MyIndexerAdapter<String> adapter = new MyIndexerAdapter<String>(
                                    getApplicationContext(), android.R.layout.simple_list_item_1,
                                    elements);
                    myListView.setAdapter(adapter);

          //          if (myListView.getFirstVisiblePosition() > adapter.getItemId( adapter.getCount()) || myListView.getLastVisiblePosition() <= adapter.getCount()) {
           //               myListView.smoothScrollToPosition( adapter.getCount());}

            }

UPDATE CODE

    class MyIndexerAdapter<T> extends ArrayAdapter<T> implements SectionIndexer {

    ArrayList<String> myElements;
    HashMap<String, Integer> alphaIndexer;
    private static final int TYPE_ITEM = 0;
    private static final int TYPE_SEPARATOR = 1;
    private static final int TYPE_MAX_COUNT = TYPE_SEPARATOR + 1;
    TreeSet mSeparatorsSet = new TreeSet();
    String[] sections;
    LayoutInflater mInflater;

    public MyIndexerAdapter(Context context, int textViewResourceId,
                    List<T> objects) {


            super(context, textViewResourceId, objects);
            mInflater=(LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            myElements = (ArrayList<String>) objects;
            // here is the tricky stuff
            alphaIndexer = new HashMap<String, Integer>();
            // in this hashmap we will store here the positions for
            // the sections

            int size = elements.size();
            for (int i = size - 1; i >= 0; i--) {
                    String element = elements.get(i);
                    alphaIndexer.put(element.substring(0, 1), i);
            //We store the first letter of the word, and its index.
            //The Hashmap will replace the value for identical keys are putted in
            }

            // now we have an hashmap containing for each first-letter
            // sections(key), the index(value) in where this sections begins

            // we have now to build the sections(letters to be displayed)
            // array .it must contains the keys, and must (I do so...) be
            // ordered alphabetically

            Set<String> keys = alphaIndexer.keySet(); // set of letters ...sets
            // cannot be sorted...

            Iterator<String> it = keys.iterator();
            ArrayList<String> keyList = new ArrayList<String>(); // list can be
            // sorted

            while (it.hasNext()) {
                    String key = it.next();
                    keyList.add(key);
            }

            Collections.sort(keyList);

            sections = new String[keyList.size()]; // simple conversion to an
            // array of object
            keyList.toArray(sections);

            // ooOO00K !

    }

 public int getItemViewType(int position)
 {
     return  mSeparatorsSet.contains(position) ? TYPE_SEPARATOR : TYPE_ITEM;
 }

 public int getViewTypeCount()
 {
     return TYPE_MAX_COUNT;
 }

    public int getPositionForSection(int section) {
            // Log.v("getPositionForSection", ""+section);
            String letter = sections[section];

            return alphaIndexer.get(letter);
    }

    public int getSectionForPosition(int position) {

            // you will notice it will be never called (right?)
            Log.v("getSectionForPosition", "called");
            getSections();
            return 0;
    }

    public Object[] getSections() {

            return sections; // to string will be called each object, to display
            // the letter
    }
    public void onListItemClick(ListView parent,View v, int position, long id)
    {

    Toast.makeText(getContext(), "you have selected" + elements.get(position), Toast.LENGTH_SHORT).show();
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        int type = getItemViewType(position);
        System.out.println("getView " + position + " " + convertView + " type = " + type);
        if (convertView == null) {
            holder = new ViewHolder();
            switch (type) {
                case TYPE_ITEM:
                    convertView = mInflater.inflate(R.layout.main, null);
                    holder.textView = (TextView)convertView.findViewById(R.id.text);
                    //break;
                case TYPE_SEPARATOR:
                    convertView = mInflater.inflate(R.layout.item1, null);
                    holder.textView = (TextView)convertView.findViewById(R.id.textSeparator);
                    break;
            }
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder)convertView.getTag();
        }
        holder.textView.setText(elements.get(position));
        return convertView;
    }

}

public void quickScroll(View v) {
    String alphabet = (String)v.getTag();
    int index = 0;
    //find the index of the separator row view
    list.setSelectionFromTop(index, 0);
}


public static class ViewHolder {
    public TextView textView;
}
}

Answer 1

In your adapter you have to override getViewTypeCount and getViewType

the latter will get the type of View that will be created by getView (In your case the view that contains only the starting letter and the view that contains the name), the former will returns the number of types of Views that will be created by getView()