I wanted to create a quick scroll with a front character to display on the screen when the user drags the alphabet list

Question

I made a contact list, how the image looks in the link below,

http://deshmukhanil.blogspot.in/2012/02/wanted-to-create-fast-scrolling-with.html

but the problem is that when I click on the list of alphabets, the charter is not displayed, it only appears when I scroll through “setFastScrollEnabled”, but I don’t want to display “FastScroll” on my screen: here is the link that shows what I want,

http://deshmukhanil.blogspot.in/2012/02/wanted-to-create-fast-scrolling-with_09.html

Answer 1

Please refer to the following code for XML.

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <ListView android:id="@+id/myListView" android:layout_width="fill_parent" android:layout_height="fill_parent"> </ListView> </LinearLayout> 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 AlphabetIndexer 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); MyIndexerAdapter<String> adapter = new MyIndexerAdapter<String>( getApplicationContext(), android.R.layout.simple_list_item_1, elements); myListView.setAdapter(adapter); } class MyIndexerAdapter<T> extends ArrayAdapter<T> implements SectionIndexer { ArrayList<String> myElements; HashMap<String, Integer> alphaIndexer; String[] sections; public MyIndexerAdapter(Context context, int textViewResourceId, List<T> objects) { super(context, textViewResourceId, objects); 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 ! } @Override public int getPositionForSection(int section) { // Log.v("getPositionForSection", ""+section); String letter = sections[section]; return alphaIndexer.get(letter); } @Override public int getSectionForPosition(int position) { // you will notice it will be never called (right?) Log.v("getSectionForPosition", "called"); return 0; } @Override public Object[] getSections() { return sections; // to string will be called each object, to display // the letter } } }