Mobile Programming Practice

▪ Explicit intent

▪ Implicit intent

▪ Intent filter

▪ Lab#4

▪ PA #1

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Prof. Hwansoo Han

T.A. Sung-in Hong

T.A. Minseop Jeong

Lecture schedule

Spring 2019 (Tuesday)

This schedule can be changed

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5 12 19 26

IntroductionAndroid overview

& basic layoutLayout Advanced UI

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2 9 16 23 30

Intent / filter

PA#1

Broadcast receivers

and ServicesProject proposal

MID TERM

(no exam)

Content providers

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7 14 21 28

Advanced concepts

(1)

APIs (1)

PA#2APIs (2) Profile

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4 11 18

Intro. to the Kotlin

Project

Final

Presentation

END TERM

(no class)

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Proposal presentation

▪ 16th Apr.

▪ ≈5 min presentation (you can change contents)

• Ex)Team members

• Idea

• Goals

• …

▪ Please upload your presentation material on i-Campus until Proposal day

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Intent

▪ An Intent is a messaging object you can use to

request an action from another app component

▪ Three fundamental use cases:

1. Starting an activity : Context.startActivity()

2. Starting a service : Context.startService()

3. Delivering a broadcast : Context.sendBroadcast()

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Intent types

▪ Explicit intents

• specify which application will satisfy the intent, by

supplying either the target app's package name or

a fully-qualified component class name

▪ Implicit intents

• do not name a specific component, but instead

declare a general action to perform, which allows a

component from another app to handle it

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Primary info. of intent

▪ Component name

• The name of the component to start

• Optional, but it’s the critical piece of info. that makes an intent explicit

▪ Action

• A string that specifies the generic action to perform

• Ex) ACTION_IMAGE_CAPTURE

▪ Data

• The URI(a Uri object) that references the data to be acted on and/or the MIME type of that data.

• URI : Uniform Resource Identifier

• MIME : type/subtype (e.g. image/jpeg)

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Primary info. of intent

▪ Category

• A string containing additional information about the

kind of component that should handle the intent

▪ Extras

• Key-value pairs that carry additional information

required to accomplish the requested action

▪ Flags

• defined in the Intent class that function as metadata

for the intent

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Explicit intent

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// Explicit Intent by specifying its class name

Intent i = new Intent(FirstActivity.this, SecondActivity.class);

// Starts TargetActivity

startActivity(i);

*https://www.tutorialspoint.com/android/android_intents_filters.htm

Creating explicit intent

▪ Constructor

• Public Intent(Context packageContext, class<?> cls);• packagageContext : the Context of current Activity

• cls : the class of target Activity

▪ Set parameter to Intent

• putExtra(String name, …); //key, value

// Explicit Intent by specifying its class nameIntent i = new Intent(FirstActivity.this, SecondActivity.class); // Explicit Intent by specifying its class namei.putExtra(“myData”,editText.getText().toString());startActivity(i);

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Receiving an explicit intent

▪ public Intent getIntent();

• Get Intent object which is submitted from previous Component

▪ public bundle getExtra();

▪ public String getStringExtra() : to get String data

▪ public String getIntExtra() : to get Int data

Intent i = getIntent();

bundle extras = i.getExtras();String text = extras.getString(“myData”);OrString text = i.getStringExtra(“myData”);

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Implicit intent

▪ An implicit intent specifies an action that can invoke

any app on the device able to perform the action.

• Using an implicit intent is useful when your app cannot perform

the action, but other apps probably can and you'd like the user to

pick which app to use.

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*http://interviewquestionanswer.com/android-questions/what-is-an-implicit-intent

Creating implicit intent

▪ Constructor

• public Intent(String action)

• public Intent(String action, Uri, uri)

▪ Action strings for instantiating Intent is

statically defined in Intent class

Please refer APPENDIX A – LIST OF

COMMON INTENTS

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Example of implicit intent

String query = "android";

Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);

intent.putExtra(SearchManager.QUERY,query);

startActivity(intent);

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Intent filter

▪ Define the actions which Component will

receive in AndroidManifest

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<activityandroid:name=".MainActivity"android:label="@string/app_name"android:theme="@style/AppTheme.NoActionBar"><intent-filter>

<action android:name="android.intent.action.MAIN" /><action android:name="android.intent.action.VIEW" /><category android:name="android.intent.category.LAUNCHER" />

</intent-filter></activity>

Example of filters

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<activity android:name="MainActivity">

<!-- This activity is the main entry, should appear in app launcher -->

<intent-filter>

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

<activity android:name="ShareActivity">

<!-- This activity handles "SEND" actions with text data -->

<intent-filter>

<action android:name="android.intent.action.SEND"/>

<category android:name="android.intent.category.DEFAULT"/>

<data android:mimeType="text/plain"/>

</intent-filter>

<!-- This activity also handles "SEND" and "SEND_MULTIPLE" with media data -->

<intent-filter>

<action android:name="android.intent.action.SEND"/>

<action android:name="android.intent.action.SEND_MULTIPLE"/>

<category android:name="android.intent.category.DEFAULT"/>

<data android:mimeType="application/vnd.google.panorama360+jpg"/>

<data android:mimeType="image/*"/>

<data android:mimeType="video/*"/>

</intent-filter>

</activity>

Receiving an implicit intent

▪ public Intent getIntent();

• Get Intent object which is submitted from previous Component

▪ public bundle getExtra();

▪ public String getStringExtra() : to get String data

▪ public String getIntExtra() : to get Int data

Intent i = getIntent();

bundle extras = i.getExtras();String text = extras.getString(“myData”);OrString text = i.getStringExtra(“myData”);

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[Lab – Practice #4]

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▪ Create two Activities

▪ The first Activity has

• One editText to input user name

• One button to deliver user name to

next activity

▪ The second Activity has

• Welcome message with user name

• One (or more) function to invoke any

other app

• Ex) set alarm, capture a picture, send

email and etc. (excepts web_search)

• You can add any view what you need

PA#1 – To do list

▪ Implement ‘to do list’ app.

▪ Login activity

• Enter the user id and password from the user

• The password should be covered on display

• Check user id and password are matched

• User id and password were predefined in your app

▪ ToDoList activity

• Has three vertical lists, named TASK, DOING and DONE

• Each card represents “job”• includes Job name, dead line, and description

• Belonging in one of lists

• Can move to another list

• Can be deleted, added and modified

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*Trello

PA#1 – To do list

▪ Individual programming assignment

▪ Recommend to use Android 8.1 Oreo (API level 27)

▪ Please upload your zipped project on i-Campus

▪ Due : 23:59, 18th Apr.

▪ A Chance to earn extra 10 credit :

• User familiar interface or extra functionality

▪ Late submission : 10% penalty per day, up to 5days

• 50% of the full score is the maximum, if you delay more than 5 days

▪ Submitting all PA is mandatory to earn your grade

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APPENDIX A – LIST OF

COMMON INTENTS

https://developer.android.com/g

uide/components/intents-

common

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Common intents

▪ Alarm clock

▪ Calendar

▪ Camera

▪ Contacts/People App

▪ Email

▪ File Storage

▪ Local Actions

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▪ Maps

▪ Music or Video

▪ New Note

▪ Phone

▪ Search

▪ Settings

▪ Text Messaging

▪ Web Browser

APPENDIX B – Forcing an app

chooser

https://developer.android.com/g

uide/components/intents-

filters#ForceChooser

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