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Kode ISH3J4 – Pemrograman Aplikasi Bergerak

Pemrograman MobilePertemuan II

Rahmat Fauzi, S.T.,M.T

Sistem Informasi – Fakultas Rekayasa Industri

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Sprint 1

3MINGGU LALU: MENCOBA DEBUG DI HP SENDIRI

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1.2 Layouts and resources for the UI

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5Contents

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VIEWS, VIEW GROUPS, AND VIEW HIERARCHY

THE LAYOUT EDITOR AND CONSTRAINTLAYOUT

EVENT HANDLING RESOURCES AND MEASUREMENTS

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ViewsIf you look at your mobile device, every user interface element that you see is a View.

Everything you see is a view

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What is a view?

View subclasses are basic user interface building blocks :

● Display text (TextView class), edit text (EditText class)● Buttons (Button class), menus, other controls● Scrollable (ScrollView, RecyclerView)● Show images (ImageView)● Group views (ConstraintLayout and LinearLayout)

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Button

EditText

Slider

CheckBox

RadioButton

Switch

Examples of view subclasses

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● Color, dimensions, positioning● May have focus (e.g., selected to receive user input)● May be interactive (respond to user clicks)● May be visible or not● Relationships to other views

View attributes

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ViewGroup and View hierarchy

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ViewGroup contains "child" views

● ConstraintLayout: Positions UI elements using constraint connections to other elements and to the layout edges

● ScrollView: Contains one element and enables scrolling ● RecyclerView: Contains a list of elements and enables scrolling by

adding and removing elements dynamically

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ViewGroups for layouts

Layouts ● are specific types of ViewGroups (subclasses of ViewGroup)● contain child views● can be in a row, column, grid, table, absolute

13Common Layout Classes

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LinearLayout ConstraintLayout GridLayout TableLayout

14Common Layout Classes

● ConstraintLayout: Connect views with constraints ● LinearLayout: Horizontal or vertical row● RelativeLayout: Child views relative to each other● TableLayout: Rows and columns● FrameLayout: Shows one child of a stack of children

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View hierarchy and screen layout

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The layout editor and ConstraintLayout

17The layout editor with ConstraintLayout

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● Connect UI elements to parent layout

● Resize and position elements

● Align elements to others

● Adjust margins and dimensions

● Change attributes

18What is ConstraintLayout?

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● Default layout for new Android Studio project

● ViewGroup that offers flexibility for layout design

● Provides constraints to determine positions and alignment of UI elements

● Constraint is a connection to another view, parent layout, or invisible guideline

19Layout editor main toolbar

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1. Select Design Surface: Design and Blueprint panes2. Orientation in Editor: Portrait and Landscape3. Device in Editor: Choose device for preview4. API Version in Editor: Choose API for preview5. Theme in Editor: Choose theme for preview 6. Locale in Editor: Choose language/locale for preview

20ConstraintLayout toolbar in layout editor

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1. Show: Show Constraints and Show Margins2. Autoconnect: Enable or disable3. Clear All Constraints: Clear all constraints in layout4. Infer Constraints: Create constraints by inference5. Default Margins: Set default margins6. Pack: Pack or expand selected elements7. Align: Align selected elements8. Guidelines: Add vertical or horizontal guidelines9. Zoom controls: Zoom in or out

21Autoconnect

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● Enable Autoconnect in toolbar if disabled

● Drag element to any part of a layout

● Autoconnect generates constraints against parent layout

22ConstraintLayout handles

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1. Resizing handle2. Constraint line and handle3. Constraint handle4. Baseline handle

23Align elements by baseline

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1. Click the baseline constraint button

2. Drag from baseline to other element's baseline

24Attributes pane

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● Click the Attributes tab● Attributes pane includes:

○ Margin controls for positioning

○ Attributes such as layout_width

25Attributes pane view inspector

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1. Vertical view size control specifies layout_height

2. Horizontal view size control specifies layout_width

3. Attributes pane close button

26Set attributes example: TextView

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27Preview layouts

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Preview layout with horizontal/vertical orientation:

1. Click Orientation in Editor button2. Choose Switch to Landscape or Switch to Portrait

Preview layout with different devices:

1. Click Device in Editor button 2. Choose device

28Create layout variant for landscape

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1. Click Orientation in Editor button

2. Choose Create Landscape Variation

3. Layout variant created: activity_main.xml (land)

4. Edit the layout variant as needed

29Create layout variant for tablet

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1. Click Orientation in Layout Editor

2. Choose Create layout x-large Variation

3. Layout variant created: activity_main.xml (xlarge)

4. Edit the layout variant as needed

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Event Handling

31Events

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Something that happens

● In UI: Click, tap, drag

● Device: DetectedActivity such as walking, driving, tilting

● Events are "noticed" by the Android system

32Event Handlers

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Methods that do something in response to a click

● A method, called an event handler, is triggered by a specific event and does something in response to the event

33Attach in XML and implement in Java

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Attach handler to view in XML layout:android:onClick="showToast"

Implement handler in Java activity:public void showToast(View view) {

String msg = "Hello Toast!";Toast toast = Toast.makeText(

this, msg, duration);toast.show();}

}

34Alternative: Set click handler in Java

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final Button button = (Button) findViewById(R.id.button_id);button.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {String msg = "Hello Toast!";Toast toast = Toast.makeText(this, msg, duration);toast.show();}

});

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Resources and measurements

36Resources

● Separate static data from code in your layouts.

● Strings, dimensions, images, menu text, colors, styles

● Useful for localization

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37Where are the resources in your project?

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resources and resource filesstored in res folder

38Values Folder

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Name File DescriptionColor res/values/colors.xml Define colorDimensions res/values/dimens.xml Define size i.g. padding,

margin, font, etc.Strings res/values/strings.xml Define textStyles res/values/styles.xml Define Style

39Refer to resources in code

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● Layout:R.layout.activity_main

setContentView(R.layout.activity_main);

● View:R.id.recyclerview

rv = (RecyclerView) findViewById(R.id.recyclerview);

● String:In Java: R.string.titleIn XML: android:text="@string/title"

40Measurements

● Density-independent Pixels (dp): for Views

● Scale-independent Pixels (sp): for text

Don't use device-dependent or density-dependent units:

● Actual Pixels (px)

● Actual Measurement (in, mm)

● Points - typography 1/72 inch (pt)

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Textview

42TextView for text

● TextView is View subclass for single and multi-line text

● EditText is TextView subclass with editable text

● Controlled with layout attributes

● Set text:○ Statically from string resource in XML

○ Dynamically from Java code and any source

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43Formatting text in string resource

● Use <b> and <i> HTML tags for bold and italics

● All other HTML tags are ignored

● String resources: one unbroken line = one paragraph

● \n starts a new a line or paragraph

● Escape apostrophes and quotes with backslash (\", \')

● Escape any non-ASCII characters with backslash (\)

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44Creating TextView in XML

<TextView android:id="@+id/textview"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:text="@string/my_story"/>

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45Common TextView attributes

android:text—text to displayandroid:textColor—color of textandroid:textAppearance—predefined style or themeandroid:textSize—text size in spandroid:textStyle—normal, bold, italic, or bold|italicandroid:typeface—normal, sans, serif, or monospaceandroid:lineSpacingExtra—extra space between lines in sp

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46Formatting active web links

<string name="article_text">... www.rockument.com ...</string>

<TextViewandroid:id="@+id/article"android:layout_width="wrap_content"android:layout_height="wrap_content"android:autoLink="web"android:text="@string/article_text"/>

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Don’t use HTML for a web link in free-form text

autoLink values:"web", "email", "phone", "map", "all"

47Creating TextView in Java code

TextView myTextview = new TextView(this);

myTextView.setWidth(LayoutParams.MATCH_PARENT);

myTextView.setHeight(LayoutParams.WRAP_CONTENT);

myTextView.setMinLines(3);

myTextView.setText(R.string.my_story);

myTextView.append(userComment);

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ScrollView

49What about large amounts of text?

● News stories, articles, etc…● To scroll a TextView, embed it in a ScrollView● Only one View element (usually TextView) allowed in a

ScrollView● To scroll multiple elements, use one ViewGroup (such as

LinearLayout) within the ScrollView

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50ScrollView for scrolling content

● ScrollView is a subclass of FrameLayout● Holds all content in memory● Not good for long texts, complex layouts● Do not nest multiple scrolling views● Use HorizontalScrollView for horizontal scrolling● Use a RecyclerView for lists

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<ScrollViewandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_below="@id/article_subheading">

<TextViewandroid:layout_width="wrap_content"android:layout_height="wrap_content".../>

</ScrollView>

ScrollView layout with one TextView

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<ScrollView ...<LinearLayout

android:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="vertical">

<TextViewandroid:id="@+id/article_subheading" .../>

<TextViewandroid:id="@+id/article" ... />

</LinearLayout></ScrollView>

ScrollView layout with a view group

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53ScrollView with image and button

<ScrollView...>

<LinearLayout...>

<ImageView.../>

<Button.../>

<TextView.../>

</LinearLayout>

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Children of the layout

One child of ScrollViewwhich can be a layout

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Hallo Toast

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SI4108 :bit.ly/Video1SI4108

(Terakhir 23.59 Selasa, 28 Januari 2020)

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Pengumpulan Praktikum

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Thank YouAny Question ? ?

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Daftar Referensi

1) https://developer.android.com/courses/fundamentals-training/toc-v2