To develop apps for Android devices, you use a set of tools that are included in the Android SDK. Once you've downloaded and installed the SDK, you can access these tools right from your Eclipse IDE, through the ADT plugin, or from the command line. Developing with Eclipse is the preferred method because it can directly invoke the tools that you need while developing applications.
However, you may choose to develop with another IDE or a simple text editor and invoke the tools on the command line or with scripts. This is a less streamlined way to develop because you will sometimes have to call command line tools manually, but you will have access to the same number of features that you would have in Eclipse.
The basic steps for developing applications (with or without Eclipse) are shown in figure 1. The development steps encompass four development phases, which include:
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SETUP :-
During this phase you install and set up your development environment. You also create Android Virtual Devices (AVDs) and connect hardware devices on which you can install your applications.
See Managing Virtual Devices and Using Hardware Devices for more information.
DEVELOPMENT :-
During this phase you set up and develop your Android project, which contains all of the source code and resource files for your application. For more information, see Create an Android project.
DEBUGGING AND TESTING :-
During this phase you build your project into a debuggable .apk package that you can install and run on the emulator or an Android-powered device. If you are using Eclipse, builds are generated each time you project is saved. If you're using another IDE, you can build your project using Ant and install it on a device using adb. For more information, see Build and run your application.
Next, you debug your application using a JDWP-compliant debugger along with the debugging and logging tools that are provided with the Android SDK. Eclipse already comes packaged with a compatible debugger. For more information see, Debug your application with the SDK debugging and logging tools.
Last, you test your application using various Android SDK testing tools. For more information, see Test your application with the Testing and Instrumentation framework.
PUBLISHING :-
During this phase you configure and build your application for release and distribute your application to users. For more information, see Publishing Overview.
JAVA INTRODUCTION :-
ava is a programming language created by James Gosling from Sun Microsystems (Sun) in 1991. The first publicly available version of Java (Java 1.0) was released in 1995.
Sun Microsystems was acquired by the Oracle Corporation in 2010. Oracle has now the steermanship for Java.
Over time new enhanced versions of Java have been released. The current version of Java is Java 1.7 which is also known as Java 7.
From the Java programming language the Java platform evolved. The Java platform allows software developers to write program code in other languages than the Java programming language and still runs on the Java virtual machine. The Java platform is usually associated with the Java virtual machine and the Java core libraries.
JAVA VIRTUAL MACHINE :-
Java programs are compiled by the Java compiler into bytecode. The Java virtual machine interprets this bytecode and executes the Java program.
Java Runtime Environment vs. Java Development Kit
A Java distribution comes typically in two flavors, the Java Runtime Environment (JRE) and the Java Development Kit (JDK).
The Java runtime environment (JRE) consists of the JVM and the Java class libraries and contains the necessary functionality to start Java programs.
The JDK contains in addition the development tools necessary to create Java programs. The JDK consists therefore of a Java compiler, the Java virtual machine, and the Java class libraries.
Characteristics of Java
he target of Java is to write a program once and then run this program on multiple operating systems.
Java has the following properties:
Platform independent: Java programs use the Java virtual machine as abstraction and do not access the operating system directly. This makes Java programs highly portable. A Java program (which is standard complaint and follows certain rules) can run unmodified on all supported platforms, e.g. Windows or Linux.
Object-orientated programming language: Except the primitive data types, all elements in Java are objects.
Strongly-typed programming language: Java is strongly-typed, e.g. the types of the used variables must be pre-defined and conversion to other objects is relatively strict, e.g. must be done in most cases by the programmer.
Interpreted and compiled language: Java source code is transferred into the bytecode format which does not depend on the target platform. These bytecode instructions will be interpreted by the Java Virtual machine (JVM). The JVM contains a so called Hotspot-Compiler which translates performance critical bytecode instructions into native code instructions.
Automatic memory management: Java manages the memory allocation and de-allocation for creating new objects. The program does not have direct access to the memory. The so-called garbage collector deletes automatically objects to which no active pointer exists.
The Java syntax is similar to C++. Java is case sensitive, e.g. variables called myValue and myvalue are treated as different variables.
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