If you need to perform some operations with a given Android contact, a contact selector might prove useful.
For this, a few steps are involved:
– define a cursor, to access all visible contacts
– populate a listview
– add a search filter to make the selection easier
– on filter change event, refine de query cursor and update the contacts list accordingly.
As in the previous samples for the Android Contacts tutorials, special permissions must be defined in AndroidManifest.xml:

Android Contacts – Add a new Contact using ContentProvider
Android Contacts – Custom Contact column to get the LOOKUPKEY
Android Contacts – Invoke the Edit Contact Intent
Android Contacts – Searching for contacts

To start, we create a simple interface with a editext for the filter, and a listview. It’s the classic Header+Scrollable content+Footer GUI design presented here.

Initially the Listview is populated by calling the ReadContacts(String sort) function with sort=”” (so all contacts are displayed):

void ReadContacts(String sort) {
	final Uri uri = ContactsContract.Contacts.CONTENT_URI;
	final String[] projection = new String[] {
			ContactsContract.Contacts._ID,
			ContactsContract.Contacts.DISPLAY_NAME
	};
	String selection = ContactsContract.Contacts.IN_VISIBLE_GROUP + " = '1'";
	String[] selectionArgs = null;
	final String sortOrder = ContactsContract.Contacts.DISPLAY_NAME + " COLLATE LOCALIZED ASC";

	m_curContacts = managedQuery(uri, projection, selection, selectionArgs, sortOrder);
	String[] fields = new String[] {ContactsContract.Data.DISPLAY_NAME};
	m_slvAdapter = new SimpleCursorAdapter(this, 
			android.R.layout.simple_list_item_1, 
			m_curContacts,
			fields, 
			new int[] {android.R.id.text1});
	m_slvAdapter.setFilterQueryProvider(new FilterQueryProvider() {
 
		public Cursor runQuery(CharSequence constraint) {
			Log.d(LOG_TAG, "runQuery constraint:"+constraint);
			String selection = ContactsContract.Contacts.IN_VISIBLE_GROUP + " = '1'" +
				" AND "+ ContactsContract.Contacts.DISPLAY_NAME + " LIKE '%"+constraint+"%'";
			String[] selectionArgs = null;
			Cursor cur = managedQuery(uri, projection, selection, selectionArgs, sortOrder);
			return cur;
		}
	
	});
	m_lvContacts.setAdapter(m_slvAdapter); 		 
}

This function looks similar to those presented in the previous article on Android contacts. Since for the listview content we’re using a SimpleCursorAdapter, we need to define a FilterQueryProvider() . runQuery is called every time the text in the EditText changes, as a result to the callback code:

public void onTextChanged(CharSequence s, int start, int before, int count) {
	if (m_slvAdapter!=null) {
		m_slvAdapter.getFilter().filter(s);
		m_lvContacts.setAdapter(m_slvAdapter); 
	}
}

m_slvAdapter.getFilter().filter(s); results in calling runQuery – this will run another managedQuery command to only select the contacts that contain the given String (LIKE ‘%”+constraint+”%’). Easy.

To get the onTextChanged callback on the EditText, it must be set accordingly:

m_etSearch.addTextChangedListener((TextWatcher) this);

Clicking the listview items, returns the item and a few details, extracted from the current cursor:

public void onItemClick(AdapterView arg0, View v, int position, long id) {
	Cursor cursor = (Cursor) m_lvContacts.getItemAtPosition(position);
	String szDisplayName = cursor.getString(cursor.getColumnIndexOrThrow( ContactsContract.Contacts.DISPLAY_NAME));
	String szId = cursor.getString(cursor.getColumnIndexOrThrow( ContactsContract.Contacts._ID));
	int nId = cursor.getInt(cursor.getColumnIndexOrThrow( ContactsContract.Contacts._ID));
	
	Log.d(LOG_TAG, "Item click:"+position+" szId:"+szId+" nId:"+nId+" Data:"+szDisplayName);
	Toast.makeText(getBaseContext(), "Item click:"+position+" szId:"+szId+" nId:"+nId+" Data:"+szDisplayName, Toast.LENGTH_SHORT).show();
}

Easy, and works extremely quickly. The complete project source code is available here:
AndroidContactsSelector