Archive for august, 2011
Android este o platforma open source pentru dezvoltarea si rularea de aplicatii mobile, dezvoltata de Google si Open Handset Alliance. Initial creata pentru telefoane mobile, Android a devenit o platforma majora de aplicatii pentru o gama larga de dispozitive mobile.
Scopul acestui post este de a descrie pasii necesari configurarii mediului de dezvoltare astfel incat sa permita unui programator sa inceapa sa invete si sa dezvolte aplicatii mobile pentru Android.
Tutorialul Android acopera toate conceptele importante ce permit unui programator nou sa invete sa dezvolte aplicatii mobile pentru platforma Android. Tutorialul este scris din perspectiva unui programator şi intra după puţine subiecte ce descriu platforma Android, în aplicatii simple, de tipul “Cum se face …” , care sunt usor de urmat. În ciuda simplitaţii aparente, fiecare parte a tutorialului evidenţiază elementele importante ale platformei Android şi sintetizeaza aspecte descrise în detaliu pe portalul developer.android.com.
In this post we will see what are the basics for developing an Android mobile application that has multiple windows or activities. To do that, we need to know how to create and display a new form, window or activity (for the rest of the post we will use the Android vocabulary and call it just activity).
We have seen in the previous parts of the Android Tutorial which are the fundamentals of an Android application and its components. Also we have seen that behind a window there is an Activity type instance that has a lifecycle and a display.
Behind any window or form in the Android mobile application there is an Activity instance. In order to develop a mobile application with multiple windows you must create, for each display, a new class that extends Activity class.
In this post we will see how to create a new Activity programmatically or using the Manifest WYSIWYG graphical editor that comes with the Android ADT Plugin for Eclipse.
This article describes different methods of changing a QR code in Photoshop that allow to insert a logo, image or text. The custom or branded QR code will be read correctly despite the modification.
The QR (Quick Response code, Denso Barcode, ISO/IEC18004) code represents a two-dimensional code bar, initially used by industry, but widely used today to encode and transmit short information, like URLs, phone numbers, contact information, business cards, meetings, GPS locations, email. The transmission is done visually and the receiver is a mobile device that has a camera and a code reader software.
QR codes were created in 1994 by a subsidiary of Toyota, Denso Wave , to be used by the carmaker in the management of various auto parts. QR Codes were use din the production for fast visual identification of components and for storing additional information.
Codurile QR (Quick Response code, Denso Barcode, ISO/IEC18004) reprezinta un cod de bare matriceal (bi-dimensional) utilizat in prezent pentru a transmite rapid informatii scurte de tip (URL, telefon, adresa contact, carte de vizita, intalnire, pozitie geografica, email) catre dispozitive mobile.
Codurile QR au fost create in 1994 de o subsidiara Toyota, Denso Wave, pentru a fi folosite de constructorul de masini in managementul diferitelor componente auto. Codurile QR au permis implementarea unui mecanism de identificare vizuala rapida a acestora si posibilitatea stocarii de informatii suplimentare.
Android mobile applications are relying on user interfaces composed on dialog windows, visual controls, 2D graphics and other multimedia elements for efficiency and usability. The Android platforms allows programmers to use two methods to design user interfaces: procedural or declarative.
In this post we develop a simple Android mobile applications that will help to make an analysis on procedural vs. declarative design of user interfaces.
Procedural means to use only Java code to design the user interface. This is something usual in designing Swing interfaces on JSE platform or designing user interfaces in J2ME MIDlets. Because every element of the user interface is managed by different classes instance, designing means to create them and to manage them.
Declarative means to use a descriptive markup language, as XHTML or XML, to describe the user interface. This is similar to how simple HTML pages are done. The designer describes the page look and the browser interprets and generates the user interface.
The Android tutorial covers all important concepts that will allow a new programmer to learn how to develop mobile applications for the Android platform. The tutorial is written from a programmer perspective and dives after few topics into simple and do-by-example applications which are easy to follow. Despite the apparently simplicity, each topic highlights important aspect of the Android platform and synthetize aspects described in detail on the developer.android.com portal.
Topics posted until now:
How to encrypt/decrypt files in Java with AES in CBC mode using Bouncy Castle API and NetBeans or Eclipse
The Bouncy Castle Crypto API for Java provides a lightweight cryptography API that is an alternative to the standard Sun Java Cryptographic Architecture (JCA) and Java Cryptographic Extension (JCE) bundled in the JDK. The API can be used in J2ME MIDlet applications or in other Java applications up to the 1.7 platform.
The Bouncy Castle lightweight cryptographic API can be used as a:
- Cryptographic Service Provider (CSP) for the JCA;
- external library.
In this post we will see how to use the the Bouncy Castle lightweight cryptographic API in both situations, as the syntax differs from one approach to the other. To highlight the differences, the advantages and the disadvantages of the two solutions, the Bouncy Castle API is used in a console Java application to encrypt/decrypt files with the AES (Advanced Encryption Standard) or Rijndael algorithm in Cipher Block Chaining (CBC) mode.
When processing binary values it is very difficult to read or to display them because any printing function generates a String value. The problem with this approach is that not all byte values can be interpreted as a printable char (i.e. the 0 binary value represents the NUL symbol; for more details check ASCII Codes + HTML Codes and Special Characters) and the resulting String will not contain all the byte values or it will not be accurate. Moreover in Java a char is stored on 2 bytes.
In this post we will see how to convert a byte array to a Hex String in a Java application. The solution is useful because:
- printing binary values in base 2 or base 10 format can become difficult to read as the value can have multiple digits;
- is easier to read values in hexadecimal base;
- it is easier to check or compare values in hexadecimal base.