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Android App Basics

Dr. David Janzen

Except as otherwise noted, the content of this presentation is

licensed under the Creative Commons Attribution 2.5 License.

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A First Example: Advent Devotions

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UML Class Diagram

Generated by Android

External Activity

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Two Activities in Advent Devotions

AdventDevos displays

the calendar of dates

Devo displays a single

devotion

Intent myIntent = new Intent(AdventDevos.this, Devo.class);

myIntent.putExtra("ButtonNum", "" + index);

startActivity(myIntent);

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Two Activities in Advent Devotions

AdventDevos displays

the calendar of dates

Devo displays a single

devotion

Bundle extras = getIntent().getExtras();

String value = extras.getString("ButtonNum");

Integer buttonNum = Integer.valueOf(value);

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Launching an Intent you didnt write

Devos has button to

URL

Browser launched

Intent i = new Intent(Intent.ACTION_VIEW,

Uri.parse("http://www.biblegateway.com/passage/?search="+

passage +"&version=NIV"));

startActivity(i);

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Android Activity An activity is a single, focused thing that

the user can do. Almost all activities

interact with the user, so the Activity class

takes care of creating a window for you in

which you can place yourUI with

setContentView(View).

http://developer.android.com/reference/android/app/

Activity.html#ActivityLifecycle

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AndroidManifest.xml

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Look around the files

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Layouts andR

esources See main.xml and devo.xml

Activity associates with layout xml file using

setContentView(R.layout.main); or

setContentView(R.layout.devo); in onCreate()

Note TableLayout and TableRow similar to

and in html Note use of dimen (see values/dimens.xml) and

color (see values/colors.xml)

Also see strings.xml

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main.xml

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devo.xml

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dimens.xml

17sp

20sp

Hello World, AdventDevos!

Advent Devotions

#AAFFFF99

#FF000000

colors.xml

strings.xml