Android™ How to Program, Second Edition

3.5. Adding Functionality to the App

Class MainActivity (Figs. 3.9–3.16) implements the Tip Calculator app’s functionality. It calculates the 15% and custom percentage tips and total bill amounts, and displays them in locale-specific currency format. To view the file, open src/com.deitel/tipcalculator and double clck MainActivity.java. You’ll need to enter most of the code in Figs. 3.9–3.16.

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 1   // MainActivity.java 2   // Calculates bills using 15% and custom percentage tips. 3   package com.deitel.tipcalculator; 4  5   import java.text.NumberFormat; // for currency formatting 6  7   import android.app.Activity; // base class for activities 8   import android.os.Bundle; // for saving state information 9   import ...