Mobile Programming Practice

▪ Layouts

▪ Adapter

▪ Lab#3

1

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

Broadcast receivers

PA#1Services Project 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)

2

Layouts

▪ The View objects are called “widgets”

• Can be one of many subclasses, such as Button or TextView

▪ The ViewGroup objects are called “layouts”

• Can be one of many types that provide a different layout

structure, such as LinearLayout or ConstraintLayout

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Layout parameters

▪ XML layout attributes named layout_something

define layout parameters for the View that are

appropriate for the ViewGroup in which it resides

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Layout position

▪ A View has a location, expressed as a

pair of left and top coordinates, and

two dimensions, expressed as a width

and a height. The unit for location and

dimensions is the pixel.

▪ It is possible to retrieve the location of

a view by invoking the methods

getLeft() and getTop()

• To avoid unnecessary computations,

getRight() and getBottom() are offered.

• getRight() returns getLeft() + getWidth()

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location

width

heig

ht

Layout Size

▪ The size of a view is expressed with a

width and a height.

▪ Drawing width and drawing height

• define the actual size of the view on the screen

• getWidth() and getHeight()

▪ Measured width and measured height

• define how big a view wants to be within its parent

• getMeasuredWidth() and getMeasuredHeight()

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Margin, border, and padding

▪ Margin

• The space between border and its parent

▪ Padding

• The space between border and content

• setPadding(int, int, int, int) : left, top, right, bottom

• getPaddingLeft(), getPaddingTop(), getPaddingRight() and getPaddingBottom()

7*https://medium.com/@geekanamika/android-beginners-views-layouts-657a5bbeebe2

Common layouts

▪ Each subclass of the ViewGroup class provides

a unique way to display the views you nest

within it.

▪ Below are some of the more common layout

types that are built into the Android platform.

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<Linear layout> <Relative layout> <Web view>

Example of LinearLayout

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<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:paddingLeft="16dp"

android:paddingRight="16dp"

android:orientation="vertical" >

<EditText

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:hint="@string/to" />

<EditText

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:hint="@string/subject" />

<EditText

android:layout_width="match_parent"

android:layout_height="0dp"

android:layout_weight="1"

android:gravity="top"

android:hint="@string/message" />

<Button

android:layout_width="100dp"

android:layout_height="wrap_content"

android:layout_gravity="right"

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

</LinearLayout>

Example of RelativeLayout

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<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:paddingLeft="16dp"

android:paddingRight="16dp" >

<EditText

android:id="@+id/name"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:hint="@string/reminder" />

<Spinner

android:id="@+id/dates"

android:layout_width="0dp"

android:layout_height="wrap_content"

android:layout_below="@id/name"

android:layout_alignParentLeft="true"

android:layout_toLeftOf="@+id/times" />

<Spinner

android:id="@id/times"

android:layout_width="96dp"

android:layout_height="wrap_content"

android:layout_below="@id/name"

android:layout_alignParentRight="true" />

<Button

android:layout_width="96dp"

android:layout_height="wrap_content"

android:layout_below="@id/times"

android:layout_alignParentRight="true"

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

</RelativeLayout>

Adapter

▪ When the content for your layout is

dynamic or not pre-determined, you can

use a layout that subclasses AdapterView

to populate the layout with views at

runtime.

▪ A subclass of the AdapterView class uses

an Adapter to bind data to its layout.

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Example of adapter

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…

import android.widget.ArrayAdapter;import android.widget.Spinner;import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {Spinner mySpinner;

@Overrideprotected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);setContentView(R.layout.layout_main); //example of RelativeLayout

mySpinner = findViewById(R.id.dates);ArrayList<String> myDates = new ArrayList<>();myDates.add("Mon, March, 25, 2019");myDates.add("Tue, March, 26, 2019");myDates.add("Wed, March, 27, 2019");ArrayAdapter<String> adapter1 = new ArrayAdapter<>(this, android.R.layout.simple_list_item_1,myDates);mySpinner.setAdapter(adapter1);

}

…

[Lab – Practice #3]

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▪ Make a list which enables to

add a new item by a user on

runtime

▪ Implement your activity to

using the list

APPENDIX A –

Layout Types and Attributes

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Layout types

▪ Linear Layout

• LinearLayout is a view group that aligns all children in a single direction, vertically or horizontally

▪ Relative Layout

• RelativeLayout is a view group that displays child views in relative positions

▪ Table Layout

• TableLayout is a view that groups views into rows and columns

▪ Absolute Layout

• AbsoluteLayout enables you to specify the exact location of its children

▪ Frame Layout

• The FrameLayout is a placeholder on screen that you can use to display a single view

▪ List View

• ListView is a view group that displays a list of scrollable items

▪ Grid View

• GridView is a ViewGroup that displays items in a two-dimensional, scrollable grid.

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Layout attributes

android:id

This is the ID which uniquely identifies the view.

android:layout_width

This is the width of the layout.

android:layout_height

This is the height of the layout

android:layout_marginTop

This is the extra space on the top side of the layout.

android:layout_marginBottom

This is the extra space on the bottom side of the layout.

android:layout_marginLeft

This is the extra space on the left side of the layout.

android:layout_marginRight

This is the extra space on the right side of the layout.

android:layout_gravity

This specifies how child Views are positioned.

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android:layout_weight

This specifies how much of the extra space in th

e layout should be allocated to the View.

android:layout_x

This specifies the x-coordinate of the layout.

android:layout_y

This specifies the y-coordinate of the layout.

android:layout_width

This is the width of the layout.

android:layout_width

This is the width of the layout.

android:paddingLeft

This is the left padding filled for the layout.

android:paddingRight

This is the right padding filled for the layout.

android:paddingTop

This is the top padding filled for the layout.

android:paddingBottom

This is the bottom padding filled for the layout.