CE53105-3 Applied Communications Technology Android lecture 2 - Structures

1. CE53105-3 Applied Communications TechnologyAndroid lecture 2 - Structures • Android File structure • Resources • Drawables • Layout • Values • R Class • Manifest • Running programs • DDMS ( Dalvik Debug Monitor Server ) • Explaining Interesting things in Notes3

2. Android File Structure Layout XML files – Used by Activities to define screens Your Project – Should be a unique name Generated folder – R class here – leave alone Resource folder – XML files defining resources Source objects for Android platform target The Manifest – Declares all bits of project Drawable Folders – Picture, image, icons etc Values folder – In this case a strings XML doc Individual Java source files Source folder – all java files you create

3. Drawable Folders • Contains images that will be used in your programs • Generally three (or one) • Drawable-hdpi – high resolution screen • Drawable –mdpi – medium resolution • Drawable- ldpi – low resolution • Means you may need several versions of your image to suit the screen resolution! • Becoming a problem as sizes proliferate • Referenced using the R class

4. Layout folder • Contains XML documents that define the layout of a particular view. • Activity’s utilise views by the setcontextview statement. • setContentView(R.layout.tigger1); • Layouts can be complex and difficult to build • DroidDraw - http://www.droiddraw.org ?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>

5. Values • Files containing tuples of data • name and value Name – Hello value – Hello World • Can be simple or complex data items • Arrays, menus etc <?xml version="1.0" encoding="utf-8"?> <resources> <string name="hello">Hello World, Viewdemo!</string> <string name="app_name">Viewdemo</string> <string-array name="countries_array"> <item>Bahrain</item> <item>Bangladesh</item> <item>Barbados</item> <item>Belarus</item> <item>Belgium</item> <item>Belize</item> <item>Benin</item> </string-array> </resources> <?xml version="1.0" encoding="utf-8"?><menu xmlns:android="http://schemas.android.com/apk/res/android">    <item android:id="@+id/new_game"          android:icon="@drawable/ic_new_game"          android:title="@string/new_game" />    <item android:id="@+id/quit"          android:icon="@drawable/ic_quit"          android:title="@string/quit" /></menu>

6. The R Class /* AUTO-GENERATED FILE. DO NOT MODIFY. package ac.uk.ere1.Viewdemo; public final class R { public static final class array { public static final int countries_array=0x7f050000; } public static final class attr { } public static final class drawable { public static final int icon=0x7f020000; } public static final class id { public static final int entry=0x7f060001; public static final int label=0x7f060000; public static final int ok=0x7f060002; } public static final class layout { public static final int linearlayoutdemo=0x7f030000; public static final int list_item=0x7f030001; public static final int main=0x7f030002; public static final int relativelayoutdemo=0x7f030003; } public static final class string { public static final int app_name=0x7f040001; public static final int hello=0x7f040000; } } • contains resource IDs for all the resources in your res/ directory • Generated by aapt (Android Asset Packaging Tool) • For each type of resource, there is an R subclass • for each resource of that type, there is a static integer • To use the resource simply add it to your code • R.string.hello or 0x7f040000 • R.layout.linearlayoutdemo or 0x7f030000 • R.array.countries_array or 0x7f050000 • Means that you can change details without having to change the code!

7. The DDMS Perspective Emulators Running Directory Structure of emulator (can push and pull files) Emulator controls – can simulate various phone actions eg receiving a call or gaining GPS input Log provides useful information on what is happening live!

8. Android Manifest Package definition Permissions Required Intent Filter defines what it can do <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="ac.uk.ere1.Viewdemo" android:versionCode="1" android:versionName="1.0“ <application android:icon="@drawable/icon" android:label="@string/app_name"> <activity android:name=".Viewdemo" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name="Listview" /> <activity android:name="Linearlayout" /> <activity android:name="Relativelayout" /> <!-- <activity android:name="Tablelayout" /> <activity android:name="Gridview" /> <activity android:name="Tablayout" /> --> </application> <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" /> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> <uses-permission android:name="android.permission.BATTERY_STATS" /> <uses-sdk android:minSdkVersion="3"></uses-sdk> </manifest> Activities Activities Commented out

9. Notepadv3 Key Points <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.android.demo.notepad3"> <application android:icon="@drawable/icon"> <activity android:name=".Notepadv3" android:label="@string/app_name"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <activity android:name=".NoteEdit" /> </application> </manifest>

10. Notepadv3 (cont) 1- @overide – places an existing definition of the method. 2- super is the root definition and is called to ensure all methods and properties are properly instantiated. 3- setContentview(R.layout.notes_list) – used to define the view being used by the activity. In this case note_list! 4- a- call to a method defined in this class. b- the method definition. 5- Intent starting a new activity (ACTIVITY_CREATE) Note it expects the activity to return a result! 6- Intent starting a new activity (ACTIVITY_EDIT) Also expecting a result to be returned. Note i.putExtra method – allows data to be transmitted to activity. 7- The method dealing with the result returned. 8- Have to create ‘listeners’ for each view item – problematical!