Android Project Anatomy

Transcription

1 Android Project Anatomy What is JDK, SDK, ADT, AVD and Eclipse!! When you complete lab0 you will notice that we have installed a lot of components in order to start developing android. The figure below shows the relations between these components ( The big picture ). Eclipse IDE We write our code here Much like Netbeans ADT Plug-in Android Development Tool a plug-in to make using eclipse easier and provide some wizards for designing interfaces and viewing xml files. Android SDK Software Development Toolkit Contains all APIs, Libraries and Documentation used to develop android apps Download new platforms Android AVD Android Virtual Device Simple tool used to create Android emulator (Virtual machines). Java JDK : Java Development Toolkit 1

2 Project Files and Folders When you first create an Android project, you will get these files and folders created Package of the project Java Source code files Auto generated Java files External resources including photos, Layouts, String and so on. Android manifest.xml a file used to control general application configuration What makes an Android Application? 1. Components o Activities. (This lab) o Services. o Content providers. o Broadcast receivers. 2. Manifest file. (This lab) 3. Resources. (This lab) Others will be covered later. 2

3 Activities One of the fundamental units in android applications. Simply, a single screen with a user interface. You might think of it as a Frame in JAVA. An activity is composed form : a java source file and an XML for user interface. Activities' interfaces could be built with code but we will lose the code-interface separation! An Application consists of multiple activities. When you create a new android project you will have completely running android application : the hello world application. We said that an activity should have a java class that extends the activity class and an.xml file to define the interface. Let's check that out! package nour.myfirstproject; import android.app.activity; import android.os.bundle; FirstProject.java public class FirstProject extends Activity { /** Called when the activity is first created. public void oncreate(bundle savedinstancestate) { } } super.oncreate(savedinstancestate); setcontentview(r.layout.main); main.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android=" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /> </LinearLayout> 3

4 Note that the method setcontentview(r.layout.main); are used to connect the activity code to its xml interface! But what is R.layout? When compiling code android generates the class R that contains all references to resources folders shown previously. Lab Work Create another activity and interface then bind then together. AndroidManifest.xml Extremely important file that introduces your application to the android system. When you create your application this files looks like this : AndroidManifest.xml <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android=" package="nour.myfirstproject" android:versioncode="1" android:versionname="1.0"> </manifest> <uses-sdk android:minsdkversion="10" /> <application android:icon="@drawable/ic_launcher" android:label="@string/app_name"> <activity android:name=".firstproject" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.main" /> <category android:name="android.intent.category.launcher" /> </intent-filter> </activity> </application> As you can see most of our application's settings like version, icon, sdk, activities and permissions. Simple but important! 4

5 Lab Work Add your activity to the android manifest file. Try to bind the activities built before. External Resources Application resources are stored under the res/ folder of your project hierarchy. In this folder each of the available resource types are stored in a subfolder containing those resources. drawable/ Bitmap files (.png,.9.png,.jpg,.gif) or XML files that are compiled into the following drawable resource subtypes: Bitmap files Nine-Patches (re-sizable bitmaps) State lists Shapes Animation drawables layout/ XML files that define a user interface layout. values/ XML files that contain simple values, such as strings, integers, and colors. Lab Work Why the folder drawable is repeated 4 times? Based on the above answer : Try to change your application icon. Try to change language to Arabic without changing the code!! 5

6 Homework Follow Steps from lab0 to prepare your environment. Try doing the Labworks by yourself. Reports should be Done individually : Groups are for projects only! 6