3. Tip Calculator App
Objectives
In this chapter you’ll:
Design a GUI using LinearLayouts and a GridLayout.
Use the IDE’s Outline window to add GUI components to LinearLayouts and a GridLayout.
Use TextView, EditText and SeekBar GUI components.
Use Java object-oriented programming capabilities, including classes, objects, interfaces, anonymous inner classes and inheritance to add functionality to an Android app.
Programmatically interact with GUI components to change the text that they display.
Use event handling to respond to user interactions with an EditText and a SeekBar.
Specify that the keypad should always be displayed when an app is executing.
Specify that an app supports only portrait orientation.
3.2 Test-Driving the Tip Calculator App
3.3.2 Activity Lifecycle Methods
3.3.3 Arranging Views with LinearLayout and GridLayout
3.3.5 Formatting Numbers as Locale-Specific Currency and Percentage Strings
3.3.6 Implementing Interface TextWatcher for Handling EditText Text Changes
3.3.7 Implementing Interface OnSeekBarChangeListener for Handling SeekBar Thumb Position Changes
3.4.2 Creating the TipCalculator Project
3.4.3 Changing to a GridLayout
3.4.4 Adding the TextViews, EditText, SeekBar and LinearLayouts
3.4.5 Customizing the Views to Complete the Design
3.5 Adding Functionality to the App
Self-Review Exercises | Answers to Self-Review Exercises | Exercises