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Android training day 2
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Android training day 2


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Android Training Day 2 slide organized in Mobile Nepal from 22nd sept, 2013 to 28th sept, 2013 for beginner level

Android Training Day 2 slide organized in Mobile Nepal from 22nd sept, 2013 to 28th sept, 2013 for beginner level

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  • 1. Android Apps Development – Training Day - 2
  • 2. XML ● Android's defined tags ● Used to define some of the resources: – Layouts – Strings ● Android Manifest ● Preferred way for defining UI elements: – Separation of code
  • 3. R class ● Auto-generated: DO NOT EDIT ● Contains ID of the project resources ● Use findViewById and Resources object to get access to the resources: – E.g. Button = (Button)findViewById(; – E.g. getResources().getString(R.string.hello);
  • 4. Layout ● Eclipse has a great UI creator – Generates all the XML for you ! ● Composed of View objects ● Can be specified for portrait or landscape – Different designs for different orientation.
  • 5. Contd. ● A layout/activity is composed of Views and ViewGroups. ● View is something that is visible. ● Examples: – TextViews, Buttons, TimePicker, DatePicker
  • 6. Contd. – Button ● <Button android:id = “@+id/button” android:layout_width = “fill_parent” android:layout_height = “wrap_content” android:text = “Button”/> There are 3 ways to declaring width and height: a. fill_parent b. wrap_content c. match_parent Do not forget to define us :)
  • 7. Contd. – EditText ● <EditText android:id= “@+id/number” android:layout_width= “fill_parent” android:layout_height= “wrap_content” android:inputType= “number”/> You can change the type of inputs as necessary
  • 8. Contd. – TextView ● <TextView android:id= “@+id/result” android:layout_height= “wrap_content” android:layout_width= “fill_parent” android:visibility= “invisible”/> Visibility types: a. visible b. invisible c. gone
  • 9. Contd. ● ViewGroups are the building blocks to Views: – This is the <body> to your View – One or more View can be grouped into a ViewGroup ● Types to ViewGroups: – LinearLayout* – RelativeLayout* – FrameLayout – TableLayout – ScrollView*, etc.
  • 10. ● Each layout has something unique to it ● Each layout has a purpose !
  • 11. LinearLayout ● <LinearLayout xmlns:android=" droid" android:layout_width= “match_parent” android:layout_height= “match_parent” android:orientation= “vertical”> … (TextViews, Buttons etc.) </LinearLayout> Declaring the XML namespace (done in the 1st ViewGroup) Unique for this ViewGroup a. vertical b. horizontal
  • 12. RelativeLayout ● Does not have any android:orientation. ● Affects the layouts inside it. ● Views are arranged according to references.
  • 13. Contd. ● <RelativeLayout … > <Button android:id= “@+id/btn” android:layout_alignParentTop= "true" … /> <TextView android:layout_below = “@id/btn” … /> <TextView android:layout_toRightOf = “@id/btn” …/> <TextView android:layout_toLeftOf = “@id/btn” …/> <TextView android:layout_alignParentBottom = “true” .../> </RelativeLayout> Various other positioning techniques also there: alignLeft alignBaseLine above, etc.
  • 14. LinearLayout VS. RelativeLayout LinearLayout RelativeLayout
  • 15. Lets Unite ! <LinearLayout … > <RelativeLayout … > … </RelativeLayout> </LinearLayout> ● You can use Viewgroups within Viewgroups : LAYOUTCEPTION !
  • 16. Building a simple UI Redirect to another page with all the filled details
  • 17. What is needed for this? ● Intents – <a href= “target”>page 2</a> – Intent = Redirecting ! – But wait … – Intent is used to call into android's drivers, other applications as well. – Powerful inter/intra application message-passing framework.
  • 18. ● Modification in the Android Manifest: <activity android:name=".Classname"> <intent-filter> <action android:name="android.intent.action.NAME"/> <category android:name="android.intent.category.DEFAULT"/> </intent-filter> </activity> Declares an activity (an Activity subclass) that implements part of the application's visual user interface. The types of intents that an app can respond to Adds a category name to an intent filter Adds an action to an intent filter.
  • 19. ● Confused ? Don't worry ! ● Remeber this ?
  • 20. ● In your main class: Intent i = new Intent(MainActivity.this, ClassName.class); // Instantiating the intent class i.putExtra(“name”, value); // values to be sent startActivity(i); // Starting the intent ● Another class: Intent i = getIntent(); //getting the intent object String name = i.getStringExtra(“name”); //getting value from passed intent
  • 21. Explaining it all ● Create your form – UI interface – Result interface ● Create two classes that extend the UI – FormClass? – ResultClass? ● Add your ResultClass to the Android Manifest. ● Pass data from your FormClass to ResultClass using intents.
  • 22. What is Manifest ? ● Presents essential information about: – The application to the Android system ● Information the system must have before it can run any of the application's code.
  • 23. Remember this ?
  • 24. ● Name of the Java package for the application. ● It describes the components of the application — the activities, services, broadcast receivers, and content providers. ● It determines which processes will host application components. ● It declares which permissions the application must have in order to access protected parts of the API and interact with other applications. ● It also declares the permissions that others are required to have in order to interact with the application's components. ● It lists the Instrumentation classes that provide profiling and other information as the application is running. These declarations are present in the manifest only while the application is being developed and tested; they're removed before the application is published. ● It declares the minimum level of the Android API that the application requires. ● It lists the libraries that the application must be linked against.
  • 25. “Have you ever wondered what happens when you press the back button/ home button on android?”
  • 26. Activity Life Cycle