lottery.java

Beginning Java 2, SDK 1.4 Edition Exercise Code samples for this book

// Chapter 17 Exercise 3
/*
 The inner Selection class no longer implements the ActionListener interface. The
 Selection class has a new method, newSelection() that obtains a new value for the
 button. This method is called by the mouse handler in response to a MOUSE_PRESSED
 event.
 */

// Applet to generate lottery entries
import javax.swing.JButton;
import javax.swing.JApplet;
import javax.swing.JPanel;
import javax.swing.BorderFactory;

import java.awt.GridLayout;
import java.awt.FlowLayout;
import java.awt.Dimension;
import java.awt.Container;
import java.awt.Color;

import java.util.Random;               // For random number generator
import java.util.Arrays;

import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;

public class Lottery extends JApplet {
  // Generate numberCount random selections from the values array
  static int[] getNumbers() {
    int[] numbers = new int[numberCount];  // Store for the numbers to be returned
    int candidate = 0;                     // Stores a candidate selection
    for(int i = 0; i < numberCount; i++) { // Loop to find the selections

      search:
      // Loop to find a new selection different from any found so far
      for(;;) {
        candidate = values[choice.nextInt(values.length)];
        for(int j = 0 ; j<i ; j++)         // Check against existing selections
          if(candidate==numbers[j])        // If it is the same
            continue search;               // get another random selection

        numbers[i] = candidate;            // Store the selection in numbers array
        break;                             // and go to find the next
      }
    }
    Arrays.sort(numbers);                  // Sort the selections
    return numbers;                        // Return the selections
  }

  // Initialize the applet
  public void init() {
    // Set up the lucky numbers buttons...
    // Set up the selection buttons
    Container content = getContentPane();
    content.setLayout(new GridLayout(0,1));  // Set the layout for the applet

    // Set up the panel to hold the lucky number buttons
    JPanel buttonPane = new JPanel();  // Add the pane containing numbers

    // Let's have a fancy panel border
    buttonPane.setBorder(BorderFactory.createTitledBorder(
                         BorderFactory.createEtchedBorder(Color.cyan,
                                                          Color.blue),
                                                          "Every One a Winner!"));

    int[] choices = getNumbers();            // Get initial set of numbers
    MouseHandler mouseHandler = new MouseHandler();    // Create the listener
    for(int i = 0; i<numberCount; i++) {
      luckyNumbers[i] = new Selection(choices[i]);
      luckyNumbers[i].addMouseListener(mouseHandler);
      buttonPane.add(luckyNumbers[i]);
    }
    content.add(buttonPane);

    // Set up the control buttons...
    // Add the pane containing control buttons
    JPanel controlPane = new JPanel(new FlowLayout(FlowLayout.CENTER, 5, 10));  

    // Add the three control buttons
    JButton button;                                      // A button variable
    Dimension buttonSize = new Dimension(100,20);        // Button size

    controlPane.add(button = new JButton("Lucky Numbers!"));
    button.setBorder(BorderFactory.createRaisedBevelBorder());
    button.addActionListener(new HandleControlButton(PICK_LUCKY_NUMBERS));
    button.setPreferredSize(buttonSize);

    controlPane.add(button = new JButton("Color"));
    button.setBorder(BorderFactory.createRaisedBevelBorder());
    button.addActionListener(new HandleControlButton(COLOR));
    button.setPreferredSize(buttonSize);

    controlPane.add(button = new JButton("Order"));
    button.setPreferredSize(buttonSize);
    button.addActionListener(new HandleControlButton(ORDER));
    button.setBorder(BorderFactory.createRaisedBevelBorder());

    content.add(controlPane);
  }
 
  // Custom button showing lottery selection
  // Each button listens for its own events
  class Selection extends JButton {
  public Selection(int value) {
    super(Integer.toString(value));    // Call base constructor and set the label
    this.value = value;                // Save the value
    setBackground(startColor);
    setBorder(BorderFactory.createRaisedBevelBorder());    // Add button border
    setPreferredSize(new Dimension(80,20));

    // We no longer need the Selection object as the action listener
    // since the mouse handler deals with changes.
//    addActionListener(this);           // Button listens for itself
  }


  public void newSelection() {
    // Change this selection to a new selection
    int candidate = 0;
    for(;;) {                              // Loop to find a different selection
      candidate = values[choice.nextInt(values.length)];
      if(isCurrentSelection(candidate))    // If it is not different
        continue;                          // find another
      setValue(candidate);                 // We have one so set the button value
      return;
    }
  }

  // Get the value for this selection
  public int getValue() {
    return value;
  }

  // Set the value for the selection
  public void setValue(int value) {
    setText(Integer.toString(value));    // Set value as the button label
    this.value = value;                   // Save the value
  }

  // Check the value for the selection
  boolean hasValue(int possible) {
    return value==possible;               // Return true if equals current value 
  }

  // Check the current choices
  boolean isCurrentSelection(int possible) {
    for(int i = 0; i < numberCount; i++)         // For each button
      if(luckyNumbers[i].hasValue(possible))     // check against possible
        return true;                             // Return true for any =
    return false;                                // Otherwise return false 
  }

  private int value;                       // Value for the selection button
  }

  // Class defining a handler for a control button
  class HandleControlButton implements ActionListener {
    // Constructor...
    private int buttonID;   

    // Constructor
    public HandleControlButton(int buttonID) {
      this.buttonID = buttonID;                   // Store the button ID
    }

    // Handle button click
    public void actionPerformed(ActionEvent e) { 
     int[] numbers = null;
     switch(buttonID) {
        case PICK_LUCKY_NUMBERS:
          numbers = getNumbers();                  // Get maxCount random numbers
          for(int i = 0; i < numberCount; i++)
            luckyNumbers[i].setValue(numbers[i]);  // Set the button values
          break;
        case COLOR:
          Color color = new Color(
                flipColor.getRGB()^luckyNumbers[0].getBackground().getRGB());
          for(int i = 0; i < numberCount; i++)
            luckyNumbers[i].setBackground(color);  // Set the button colors
          break;
        case ORDER:                                // Sort the lucky number button values
          numbers = new int[numberCount];
          for(int i = 0; i < numberCount; i++)
            numbers[i] = luckyNumbers[i].getValue();    // Get the button values
          Arrays.sort(numbers);                         // and sort them
          for(int i = 0; i < numberCount; i++)
            luckyNumbers[i].setValue(numbers[i]);
          break;
      }
    }
  }

  final static int numberCount = 6;                   // Number of lucky numbers
  final static int minValue = 1;                      // Minimum in range
  final static int maxValue = 49;                     // Maximum in range
  static int[] values = new int[maxValue-minValue+1]; // Array of possible values
  static {                                            // Initialize array
    for(int i = 0 ; i<values.length ; i++)
      values[i] = i + minValue;
  }

  // An array of custom buttons for the selected numbers
  private Selection[] luckyNumbers = new Selection[numberCount]; 

  final public static int PICK_LUCKY_NUMBERS = 1;                // Select button ID
  final public static int COLOR = 2;                             // Color button ID
  final public static int ORDER = 3;                             // Order button ID
  
  // swap colors
  Color flipColor = new Color(Color.yellow.getRGB()^Color.red.getRGB()); 
  
  Color startColor = new Color(Color.yellow.getRGB());           // start color

  private static Random choice = new Random();        // Random number generator
}