Marakana Android User Interface
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The document discusses building user interfaces for Android applications. It explains that Android uses XML layout files and Java code to create UIs either procedurally or declaratively. Key UI components include views, view groups, adapters, and complex components like maps. The document also covers graphics, multimedia, menus, and optimizing UIs for performance.
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Marakana Android User Interface
- 1. Android User Interface Marko Gargenta Marakana
- 2. HELLO WORLD!
- 3. Create New Project Use the Eclipse tool to create a new Android project. Here are some key constructs: Project Eclipse construct Target minimum to run App name whatever Package Java package AcBvity Java class
- 4. The Manifest File <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.marakana" android:versionCode="1" android:versionName="1.0"> <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".HelloAndroid" 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> <uses-sdk android:minSdkVersion="5" /> </manifest>
- 5. The Layout Resource <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/hello" /> </LinearLayout>
- 6. The Java File package com.marakana; import android.app.Activity; import android.os.Bundle; public class HelloAndroid extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } }
- 8. Two UI Approaches Procedural Declara;ve You write Java code You write XML code Similar to Swing or AWT Similar to HTML of a web page You can mix and match both styles. Declarative is preferred: easier and more tools
- 9. XML-‐Based User Interface Use WYSIWYG tools to build powerful XML-based UI. Easily customize it from Java. Separate concerns.
- 10. Dips and Sps px (pixel) Dots on the screen in (inches) Size as measured by a ruler mm (millimeters) Size as measured by a ruler pt (points) 1/72 of an inch dp (density-‐independent pixel) Abstract unit. On screen with 160dpi, 1dp=1px dip synonym for dp and o^en used by Google sp Similar to dp but also scaled by users font size preference
- 11. Views and Layouts ViewGroup ViewGroup View View View View ViewGroups contain other Views but are also Views themselves.
- 12. Common UI Components Android UI includes many common modern UI widgets, such as Buttons, Tabs, Progress Bars, Date and Time Pickers, etc.
- 13. SelecBon Components Some UI widgets may be linked to zillions of pieces of data. Examples are ListView and Spinners (pull-downs).
- 14. Adapters Adapter Data Source To make sure they run smoothly, Android uses Adapters to connect them to their data sources. A typical data source is an Array or a Database.
- 15. Complex Components Certain high-level components are simply available just like Views. Adding a Map or a Video to your application is almost like adding a Button or a piece of text.
- 17. Graphics & AnimaBon Android has rich support for 2D graphics. You can draw & animate from XML. You can use OpenGL for 3D graphics.
- 18. MulBmedia AudioPlayer lets you simply specify the audio resource and play it. VideoView is a View that you can drop anywhere in your activity, point to a video file and play it. XML: <VideoView android:id="@+id/video" android:layout_width="fill_parent" android:layout_height="fill_parent" android:layout_gravity="center” /> Java: player = (VideoView) findViewById(R.id.video); player.setVideoPath("/sdcard/samplevideo.3gp"); player.start();
- 19. Google Maps Google Maps is an add-on in Android. It is not part of open-source project. However, adding Maps is relatively easy using MapView. XML: <com.google.android.maps.MapView android:id="@+id/map" android:clickable="true" android:layout_width="fill_parent" android:layout_height="fill_parent" android:apiKey="0EfLSgdSCWIN…A" />
- 20. Building UI for Performance A handy Hierarchy Viewer tool helps with optimizing the UI for performance
- 21. Summary Main difference between Java and Android is User Interface. Android has two approaches to UI: programmatic and declarative. Best practice is to use both. Lifecycle of an activity is very important for overall performance of your app. So, optimize your UI. Marko Gargenta, Marakana.com [email protected] +1-415-647-7000 Licensed under Creative Commons License (cc-by-nc-nd). Please Share!