Podcast
Questions and Answers
Which widget type is a digital representation of time in Android?
Which widget type is a digital representation of time in Android?
In event-driven programming, which of the following is not a common kind of event?
In event-driven programming, which of the following is not a common kind of event?
What is the purpose of the Properties panel when designing a user interface in Android?
What is the purpose of the Properties panel when designing a user interface in Android?
Which of the following statements is true about event listeners in Android?
Which of the following statements is true about event listeners in Android?
Signup and view all the answers
Which Java component is a parent class for all widget types in Android?
Which Java component is a parent class for all widget types in Android?
Signup and view all the answers
What is the first step when setting an event listener for a widget?
What is the first step when setting an event listener for a widget?
Signup and view all the answers
Which of the following is a valid method for accessing a widget's properties in Java?
Which of the following is a valid method for accessing a widget's properties in Java?
Signup and view all the answers
Which XML file is typically opened to design the main interface layout in Android?
Which XML file is typically opened to design the main interface layout in Android?
Signup and view all the answers
What is the first step to access a widget in Java code according to Android development practices?
What is the first step to access a widget in Java code according to Android development practices?
Signup and view all the answers
Which method is correctly used to retrieve the View object of a widget in Java after assigning it a unique ID?
Which method is correctly used to retrieve the View object of a widget in Java after assigning it a unique ID?
Signup and view all the answers
In the 'Bigger Number' game, what happens upon a user's guess?
In the 'Bigger Number' game, what happens upon a user's guess?
Signup and view all the answers
In Android's Toast class, which parameter specifies how long the toast message will be displayed?
In Android's Toast class, which parameter specifies how long the toast message will be displayed?
Signup and view all the answers
What is the purpose of the setText method in the button1_onclick function?
What is the purpose of the setText method in the button1_onclick function?
Signup and view all the answers
What does the 'button1_onclick' method signify in Android event-driven programming?
What does the 'button1_onclick' method signify in Android event-driven programming?
Signup and view all the answers
What is the purpose of the 'drawable/' directory within the resource files?
What is the purpose of the 'drawable/' directory within the resource files?
Signup and view all the answers
In the context of Android app development, what does 'event-driven programming' primarily focus on?
In the context of Android app development, what does 'event-driven programming' primarily focus on?
Signup and view all the answers
Which file is primarily responsible for the configuration of the build process in an Android application?
Which file is primarily responsible for the configuration of the build process in an Android application?
Signup and view all the answers
What role do widgets play in an Android activity?
What role do widgets play in an Android activity?
Signup and view all the answers
When setting up virtual devices in Android Studio, which of the following is a disadvantage of using an actual Android device for testing?
When setting up virtual devices in Android Studio, which of the following is a disadvantage of using an actual Android device for testing?
Signup and view all the answers
In creating XML layouts for Android apps, which of the following would typically be used to structure the arrangement of GUI widgets?
In creating XML layouts for Android apps, which of the following would typically be used to structure the arrangement of GUI widgets?
Signup and view all the answers
What is the key advantage of using Gradle as a build system in Android development?
What is the key advantage of using Gradle as a build system in Android development?
Signup and view all the answers
Which statement best describes the 'activity' in Android terminology?
Which statement best describes the 'activity' in Android terminology?
Signup and view all the answers
Study Notes
User Interface Components
- Action Bar: Contains a menu of common actions at the top of the app.
- Notification Area: Displays the topmost system menu and icons for alerts.
- Android Widgets: Various UI components such as:
- Analog/Digital Clock, Button, Checkbox, Date/Time Picker
- EditText, Gallery, ImageView/Button, ProgressBar
- RadioButton, Spinner, TextView, MapView, WebView
Designing a User Interface
- XML layout files (e.g., activity_main.xml) are used to define UI components.
- Widgets can be dragged from the Palette to a preview image for layout design.
- Properties for each widget can be set in the Properties panel.
Events and Event-Driven Programming
- Events: Stimuli such as mouse motion, key presses, timers, and network data.
- Event-driven programming relies on user actions to control program flow and is common in graphical applications.
- To respond to events:
- Create methods known as "listener" methods to handle specific events.
- Attach these methods to GUI widgets in the design view.
Setting an Event Listener
- Select the widget in Design view, find the onClick property, and specify the method name.
- Switch to Text view to locate the XML for the button and create the method for the click action.
View Objects
- Each widget corresponds to a Java object that is a subclass of the View class.
- View objects have various methods to get and set properties like background, ID, margins, padding, and visibility.
- Example method for a Button’s text:
public String getText()andpublic void setText(String text).
Accessing Widgets in Java Code
- Assign a unique ID value to each widget in Design view.
- Use
findViewByIdto access the widget in Java, casting it to the correct type (e.g., Button, TextView). - Example function to handle button click events: sets text in a TextView.
Exercise: Number Game
- Concept for "Bigger Number" game:
- User compares two numbers by selecting corresponding buttons.
- Displays "correct" or "incorrect" messages after each guess.
- Scoring system awards points for correct answers and penalizes for incorrect answers.
Displaying Toast Messages
- Use
Toast.makeTextto display short messages for user feedback. - Toast duration can be set to LENGTH_SHORT or LENGTH_LONG.
- Toasts are used for brief status updates but should not be relied on for critical information.
Resource Files Structure
-
drawable/: Stores images. -
layout/: Contains descriptions of the GUI layout. -
menu/: Defines overall app menu options. -
values/: Holds constant values and arrays including strings for localization data and styles for visual appearance.
Gradle Build System
- Gradle manages build/compile processes for Android projects.
- The
build.gradlefile serves as the main configuration file for project builds.
Virtual Devices (AVDs)
- AVDs allow for running projects in an emulator, simulating various Android devices.
- When running a project in Android Studio, the app builds, installs, and loads on the virtual device.
- Alternatively, apps can be tested directly on actual Android devices for better performance but require physical connectivity to a development PC.
Top-Down Design Approach
- Emphasizes starting from app design and learning required skills to build that app.
- Example application: the "Bigger Number" game incorporates user interaction through buttons to select the bigger number among two provided options.
Android Terminology
- Activity: A single screen in an app, fundamental GUI component.
- View: Elements displayed in an activity, including widgets and layouts.
- Widget: GUI controls such as buttons and text fields.
- Layout: An invisible container managing positions and sizes of widgets.
- Event: Actions triggered by user interactions with widgets.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
