Monday, November 7, 2011

Android Snippet Code: Android ListView with fast scroll and alphabetical section index

This small tutorial will show you how to create a ListView with fast scrolling and alphabetical section list that displays the letter as you quickly scroll the list.

We starting with the ListView example of HelloViews resources in the android tutorials and then apply my adapter that implements the alphabetical section indexer.

  1. Start a new project named QuicklySectionListView.
  2. Create an XML file named list_item.xml and save it inside the res/layout/ folder. This file defines the layout for each item that will be placed in the ListView. Insert the following:
     <?xml version="1.0" encoding="utf-8"?>  
     <TextView xmlns:android=""  
       android:textSize="16sp" >  
  3. Starting from the ListView example I have added an inner class that extends ArrayAdapter and implements SectionIndexer. The code is as follow:
     package com.example.quicklyscrolllistview;  
     import java.util.ArrayList;  
     import java.util.Collections;  
     import java.util.HashMap;  
     import java.util.LinkedList;  
     import java.util.Set;  
     import android.content.Context;  
     import android.os.Bundle;  
     import android.view.View;  
     import android.widget.AdapterView;  
     import android.widget.AdapterView.OnItemClickListener;  
     import android.widget.ArrayAdapter;  
     import android.widget.ListView;  
     import android.widget.SectionIndexer;  
     import android.widget.TextView;  
     import android.widget.Toast;  
     public class QuicklyScrollListViewActivity extends ListActivity {  
          // Called when the activity is first created.  
          public void onCreate(Bundle savedInstanceState) {  
               LinkedList<String> mLinked = new LinkedList<String>();  
               for (int i = 0; i < COUNTRIES.length; i++) {  
               setListAdapter(new MyListAdaptor(this, mLinked));  
               ListView lv = getListView();  
               lv.setOnItemClickListener(new OnItemClickListener() {  
                    public void onItemClick(AdapterView<?> parent, View view,  
                              int position, long id) {  
                         // When clicked, show a toast with the TextView text  
                                   ((TextView) view).getText(), Toast.LENGTH_SHORT).show();  
          static final String[] COUNTRIES = new String[] { "Afghanistan", "Albania",  
                    "Algeria", "American Samoa", "Andorra", "Angola", "Anguilla",  
                    "Antarctica", "Antigua and Barbuda", "Argentina", "Armenia",  
                    "Aruba", "Australia", "Austria", "Azerbaijan", "Bahrain",  
                    "Bangladesh", "Barbados", "Belarus", "Belgium", "Belize", "Benin",  
                    "Bermuda", "Bhutan", "Bolivia", "Bosnia and Herzegovina",  
                    "Botswana", "Bouvet Island", "Brazil",  
                    "British Indian Ocean Territory", "British Virgin Islands",  
                    "Brunei", "Bulgaria", "Burkina Faso", "Burundi", "Cote d'Ivoire",  
                    "Cambodia", "Cameroon", "Canada", "Cape Verde", "Cayman Islands",  
                    "Central African Republic", "Chad", "Chile", "China",  
                    "Christmas Island", "Cocos (Keeling) Islands", "Colombia",  
                    "Comoros", "Congo", "Cook Islands", "Costa Rica", "Croatia",  
                    "Cuba", "Cyprus", "Czech Republic",  
                    "Democratic Republic of the Congo", "Denmark", "Djibouti",  
                    "Dominica", "Dominican Republic", "East Timor", "Ecuador", "Egypt",  
                    "El Salvador", "Equatorial Guinea", "Eritrea", "Estonia",  
                    "Ethiopia", "Faeroe Islands", "Falkland Islands", "Fiji",  
                    "Finland", "Former Yugoslav Republic of Macedonia", "France",  
                    "French Guiana", "French Polynesia", "French Southern Territories",  
                    "Gabon", "Georgia", "Germany", "Ghana", "Gibraltar", "Greece",  
                    "Greenland", "Grenada", "Guadeloupe", "Guam", "Guatemala",  
                    "Guinea", "Guinea-Bissau", "Guyana", "Haiti",  
                    "Heard Island and McDonald Islands", "Honduras", "Hong Kong",  
                    "Hungary", "Iceland", "India", "Indonesia", "Iran", "Iraq",  
                    "Ireland", "Israel", "Italy", "Jamaica", "Japan", "Jordan",  
                    "Kazakhstan", "Kenya", "Kiribati", "Kuwait", "Kyrgyzstan", "Laos",  
                    "Latvia", "Lebanon", "Lesotho", "Liberia", "Libya",  
                    "Liechtenstein", "Lithuania", "Luxembourg", "Macau", "Madagascar",  
                    "Malawi", "Malaysia", "Maldives", "Mali", "Malta",  
                    "Marshall Islands", "Martinique", "Mauritania", "Mauritius",  
                    "Mayotte", "Mexico", "Micronesia", "Moldova", "Monaco", "Mongolia",  
                    "Montserrat", "Morocco", "Mozambique", "Myanmar", "Namibia",  
                    "Nauru", "Nepal", "Netherlands", "Netherlands Antilles",  
                    "New Caledonia", "New Zealand", "Nicaragua", "Niger", "Nigeria",  
                    "Niue", "Norfolk Island", "North Korea", "Northern Marianas",  
                    "Norway", "Oman", "Pakistan", "Palau", "Panama",  
                    "Papua New Guinea", "Paraguay", "Peru", "Philippines",  
                    "Pitcairn Islands", "Poland", "Portugal", "Puerto Rico", "Qatar",  
                    "Reunion", "Romania", "Russia", "Rwanda", "Sqo Tome and Principe",  
                    "Saint Helena", "Saint Kitts and Nevis", "Saint Lucia",  
                    "Saint Pierre and Miquelon", "Saint Vincent and the Grenadines",  
                    "Samoa", "San Marino", "Saudi Arabia", "Senegal", "Seychelles",  
                    "Sierra Leone", "Singapore", "Slovakia", "Slovenia",  
                    "Solomon Islands", "Somalia", "South Africa",  
                    "South Georgia and the South Sandwich Islands", "South Korea",  
                    "Spain", "Sri Lanka", "Sudan", "Suriname",  
                    "Svalbard and Jan Mayen", "Swaziland", "Sweden", "Switzerland",  
                    "Syria", "Taiwan", "Tajikistan", "Tanzania", "Thailand",  
                    "The Bahamas", "The Gambia", "Togo", "Tokelau", "Tonga",  
                    "Trinidad and Tobago", "Tunisia", "Turkey", "Turkmenistan",  
                    "Turks and Caicos Islands", "Tuvalu", "Virgin Islands", "Uganda",  
                    "Ukraine", "United Arab Emirates", "United Kingdom",  
                    "United States", "United States Minor Outlying Islands", "Uruguay",  
                    "Uzbekistan", "Vanuatu", "Vatican City", "Venezuela", "Vietnam",  
                    "Wallis and Futuna", "Western Sahara", "Yemen", "Yugoslavia",  
                    "Zambia", "Zimbabwe" };  
           * The List row creator  
          class MyListAdaptor extends ArrayAdapter<String> implements  
                    SectionIndexer {  
               HashMap<String, Integer> alphaIndexer;  
               String[] sections;  
               public MyListAdaptor(Context context, LinkedList<String> items) {  
                    super(context, R.layout.list_item, items);  
                    alphaIndexer = new HashMap<String, Integer>();  
                    int size = items.size();  
                    for (int x = 0; x < size; x++) {  
                         String s = items.get(x);  
                         // get the first letter of the store  
                         String ch = s.substring(0, 1);  
                         // convert to uppercase otherwise lowercase a -z will be sorted  
                         // after upper A-Z  
                         ch = ch.toUpperCase();  
    // put only if the key does not exist  
                         if (!alphaIndexer.containsKey(ch))
    alphaIndexer.put(ch, x);
    } Set<String> sectionLetters = alphaIndexer.keySet(); // create a list from the set to sort ArrayList<String> sectionList = new ArrayList<String>( sectionLetters); Collections.sort(sectionList); sections = new String[sectionList.size()]; sectionList.toArray(sections); } public int getPositionForSection(int section) { return alphaIndexer.get(sections[section]); } public int getSectionForPosition(int position) { return 0; } public Object[] getSections() { return sections; } } }
MyListAdaptor get a LinkedList of strings and sort it out alphabetically. The indexes have the values of the keys in the LinkedList sorted alphabetically. 
I hope this is helpful.

You can find the source code here.

Friday, July 29, 2011

Getting Started with Arduino (OS Ubuntu)

I was excited and impatient to see Arduino to work, so I immediately began to prepare the development environment on my Ubuntu machine and with a small example I gave birth to my first project with Arduino.
In this tutorial I will show you how to get ready the Arduino IDE on Ubuntu OS and an easy example of how to use it.

Installing Arduino on Ubuntu is very easy and fast, with a few steps you will have the development environment through which you can spread out your creativity handling projects based on Arduino.

You must install:

  • OpenJDK Java 6 Runtime – (Java Runtime Environment)
  • avr-libc
  • gcc-avr
  • Open-source Arduino enviroment

You can use the Ubuntu Software Center to install the OpenJDK:

OpenJDK Java 6

We install avr-libc and gcc-avr packages using the package manager:

avr-libc package

gcc-avr package

Now we have to download the development environment, go to the download area of Arduino site and download your specific version (Linux 32 or 64 bit):

Download page

After you downloaded the file, unzip it and keep the files in a folder.

WOW !! We have already finished !!

Yes, because - unlike Windows and Mac OS - since the version 2.6.31, the linux kernel includes drivers for Arduino !

For launching the Arduino development environment, do double click on the file named Arduino, included into the folder where unzipped files are. 
For more information about Arduino development environment, please refer to this link : Arduino Development Environment.

Arduino Development Environment

Our first project (very simple) 


  • Start Arduino development environment
  • Click on File -> Examples -> Basic -> Blink
  • Click Tools -> Board and select your specific board
  • Click Tools -> Serial Port -> /dev/ttyACM1
  • Upload this example code

This example code turns on for one second, then off for one second, the Led on pin 13.

When the upload is finished, your Led starts blinking. 


Blink Example Code

Tuesday, July 26, 2011

Finally... Arrived !!

Hello everyone, 
finally today my Arduino Starter kit is arrived !!

For those who don't know what Arduino is these are the links to Wikipedia and to Arduino.

For now I have nothing else to write but soon the blog will be filled with all my Arduino/Android projects !!