面试题与答案

Android supports java, c++, c# etc. language to develop android applications. Java is the officially supported language for android. All the android examples of this site is developed using Java language and Eclipse IDE.

Here, we are going to tell you, the required softwares to develop android applications using Eclipse IDE.

Simple way by ADT Bundle

It is the simplest technique to install required softwares for android application. It includes:

Eclipse IDE

Android SDK

Eclipse Plugin

If you download the ADT from android site, you don't need to have eclipse IDE, android SDK and eclipse Plugin because it is already included in adt bundle.

If you have downloaded the ADT bundle, unjar it, go to eclipse IDE and start the eclipse by clicking on the eclipse icon. You don't need to do any extra steps here.

In this page, you will learn what softwares are required for running an android application on eclipse IDE. Here, you will be able to learn how to install the android SDK ADT plugin for Eclipse IDE. Let's see the softwares required to setup android for eclipse IDE manually.

Install the JDK

Download and install the Eclipse for developing android application

Download and Install the android SDK

Intall the ADT plugin for eclipse

Configure the ADT plugin

Create the AVD

Create the hello android application

As we know the modern JVM is high performance and provides excellent memory management. But it need to be optimized for low-powered handheld devices.

The Dalvik Virtual Machine (DVM) is optimized for mobile devices. It optimizes the JVM for memory, battery life and performance.

Dalvik is a name of a town in Iceland. The Dalvik VM was written by Dan Bornstein.

The Dex compiler converts the class files into the .dex files that run on the Dalvik VM.

The javac tool compiles the java source file into the class file.

The dx tool takes all the class files of your application and generates a single .dex file. It is a platform-specific tool.

The Android Assets Packaging Tool (aapt) handles the packaging process.

The AndroidManifest.xml file contains information about your package, including components of the application such as activities, services, broadcast receivers, content providers etc.

It performs some other tasks also:

It is responsible to protect the application to access any protected parts by providing the permissions.

It also declares the android api that the application is going to use.

It lists the instrumentation classes. The instumentation classes provides profiling and other informations. These informations are removed just before the application is published etc.

This is the required xml file for all the android application and located inside the root directory.

A simple AndroidManifest.xml file looks like this:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"  

    package="com.javatpoint.hello"  

    android:versionCode="1"  

    android:versionName="1.0" >  

  

    <uses-sdk  

        android:minSdkVersion="8"  

        android:targetSdkVersion="15" />  

  

    <application  

        android:icon="@drawable/ic_launcher"  

        android:label="@string/app_name"  

        android:theme="@style/AppTheme" >  

        <activity  

            android:name=".MainActivity"  

            android:label="@string/title_activity_main" >  

            <intent-filter>  

                <action android:name="android.intent.action.MAIN" />  

  

                <category android:name="android.intent.category.LAUNCHER" />  

            </intent-filter>  

        </activity>  

    </application>  

  

</manifest>  

Elements of the AndroidManifest.xml file

The elements used in the above xml file are described below.

manifest is the root element of the AndroidManifest.xml file. It has package attribute that describes the package name of the activity class.

application is the subelement of the manifest. It includes the namespace declaration. This element contains several subelements that declares the application component such as activity etc.

The commonly used attributes are of this element are icon, label, theme etc.

android:icon represents the icon for all the android application components.

android:label works as the default label for all the application components.

android:theme represents a common theme for all the android activities.

activity is the subelement of application and represents an activity that must be defined in the AndroidManifest.xml file. It has many attributes such as label, name, theme, launchMode etc.

android:label represents a label i.e. displayed on the screen.

android:name represents a name for the activity class. It is required attribute.

intent-filter is the sub-element of activity that describes the type of intent to which activity, service or broadcast receiver can respond to.

It adds an action for the intent-filter. The intent-filter must have at least one action element.

It adds a category name to an intent-filter.