Mobile Systems and Technologies Prefinals Reviewer

Input Controls

Involves tapping, typing, using gestures, or talking

Button

Is usually a rectangle or rounded rectangle with a descriptive caption or icon in its center. It can text, icon, or both

Syntax to create a button with text

<Button

android:layout_width=”wrap_content”

android:layout_height=”wrap content”

android:src=”@string/button_text” />

Syntax to create a button with icon

<ImageButton

android:layout_width=”wrap_content”

android:layout_height=”wrap content”

android:src=”@drwable/button_icon” />

Syntax to create a button with text and icon

<Button

android:layout_width=”wrap_content”

android:layout_height=”wrap content”

android:src=”@string/button_text”

android:drawableLeft=”@drawable/button_icon” />

Three states of button

These are the states the ____ element:

• Normal

• Disabled

• Pressed

Raised Button

Appears lifted from the screen, the shading around it indicates that it is possible to tap or click it

Flat button

Also known as a borderless button, is a text-only button that looks flat and doesn’t have a shadow

ImageView

Is used to display image resources. It can be turned into a button by adding the android:onClick attribute in the XML layout

Floating Action Button

Is a circular button that appears to float above the layout

Touch Gesture

Occurs when a user places one or more fingers on the touchscreen, and the app interprets that pattern of touches as a particular gesture, such as top, touch and hold, double-tap, fling, or scroll

Input Controls

Are interactive elements in the app’s UI that accept data input

Text Field (EditText)

Is used for entering and modifying text

Syntax that stores the value of the selected option in a String

<Spinner

android:id=”@+id/language_spinner”

android:layout_width=”fill_parent”

android:layout_height=”wrap_content”

android:entries=”@array/language_array” />

String text = mySpinner.getSelectedItem().toString();

Toggle Button

Lets the user change a setting between two states

Switch

A type of toggle button, provides a slider for selection

SeekBar

Is dragged to the left or right to indicate a progress level

Event

Occurs when the user interacts with an input control or item in the user interface

Event Listener

Is an interface in the View class that contains a single callback method. These methods will be called when the View to which the listener has been registered is triggered by user interaction with the item in the UI

OnClick()

When the user either touches or focuses upon the item

onLongClick()

When the user either touches or focuses upon the item for a second

onKey()

When the user is focused on the item and presses or releases a hardware key on the device

onTouch()

When the user performs an action qualified as a touch event (a press, a release, or any movement gesture on the screen)

Drawable

Is a graphic that can be drawn to the screen. It is the class used for adding rich images in an app with a minimal impact on its performance

WebP

A modern image format developed by Google that provides superior lossless and lossy compression for images on the web

PNG

Portable Network Graphics

JPG/JPEG

Joint Photographic Experts Group

GIF

Graphics Interchange Format

BMP

Bitmap

Recommended image formats

• WebP

• PNG

• JPG

Style

A collection of attributes that define the look and format of a view

Platform Styles

The styles that Android provides

<style>

This element must include the following:

• name

• parent (optional)

• Any number of <item> elements as child elements of <style>

Inheritance

Allows a style to inherit the properties of an existing style

Theme

Is a collection of attributes that define the look and format of an activity or an entire app. Any style can be used as a theme