java

1. 1
Interaksi Obyek
Class Number Display
/**
* The NumberDisplay class represents a digital number display that can hold
* values from zero to a given limit. The limit can be specified when creating
* the display. The values range from zero (inclusive) to limit-1. If used,
* for example, for the seconds on a digital clock, the limit would be 60,
* resulting in display values from 0 to 59. When incremented, the display
* automatically rolls over to zero when reaching the limit.
*
* @author Michael Kölling and David J. Barnes
* @version 2016.02.29
*/
public class NumberDisplay
{
private int limit;
private int value;

2. 2
/**
* Constructor for objects of class NumberDisplay.
* Set the limit at which the display rolls over.
*/
public NumberDisplay(int rollOverLimit)
{
limit = rollOverLimit;
value = 0;
}
/**
* Return the current value.
*/
public int getValue()
{
return value;
}
/**
* Return the display value (that is, the current value as a two-digit
* String. If the value is less than ten, it will be padded with a leading
* zero).
*/
public String getDisplayValue()
{
if(value < 10) {
return "0" + value;
}

3. 3
else {
return "" + value;
}
}
/**
* Set the value of the display to the new specified value. If the new
* value is less than zero or over the limit, do nothing.
*/
public void setValue(int replacementValue)
{
if((replacementValue >= 0) && (replacementValue < limit)) {
value = replacementValue;
}
}
/**
* Increment the display value by one, rolling over to zero if the
* limit is reached.
*/
public void increment()
{
value = (value + 1) % limit;
}
}

4. 4
Class ClockDisplay
/**
* The ClockDisplay class implements a digital clock display for a
* European-style 24 hour clock. The clock shows hours and minutes. The
* range of the clock is 00:00 (midnight) to 23:59 (one minute before
* midnight).
*
* The clock display receives "ticks" (via the timeTick method) every minute
* and reacts by incrementing the display. This is done in the usual clock
* fashion: the hour increments when the minutes roll over to zero.
*
* @author Michael Kölling and David J. Barnes
* @version 2016.02.29
*/
public class ClockDisplay
{
private NumberDisplay hours;
private NumberDisplay minutes;
private String displayString; // simulates the actual display
/**
* Constructor for ClockDisplay objects. This constructor
* creates a new clock set at 00:00.
*/
public ClockDisplay()
{
hours = new NumberDisplay(24);
minutes = new NumberDisplay(60);

5. 5
updateDisplay();
}
/**
* Constructor for ClockDisplay objects. This constructor
* creates a new clock set at the time specified by the
* parameters.
*/
public ClockDisplay(int hour, int minute)
{
hours = new NumberDisplay(24);
minutes = new NumberDisplay(60);
setTime(hour, minute);
}
/**
* This method should get called once every minute - it makes
* the clock display go one minute forward.
*/
public void timeTick()
{
minutes.increment();
if(minutes.getValue() == 0) { // it just rolled over!
hours.increment();
}
updateDisplay();
}
/**

6. 6
* Set the time of the display to the specified hour and
* minute.
*/
public void setTime(int hour, int minute)
{
hours.setValue(hour);
minutes.setValue(minute);
updateDisplay();
}
/**
* Return the current time of this display in the format HH:MM.
*/
public String getTime()
{
return displayString;
}
/**
* Update the internal string that represents the display.
*/
private void updateDisplay()
{
displayString = hours.getDisplayValue() + ":" +
minutes.getDisplayValue();
}
}

7. 7
Class Clock-GUI
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
/**
* A very simple GUI (graphical user interface) for the clock display.
* In this implementation, time runs at about 3 minutes per second, so that
* testing the display is a little quicker.
*
* @author Michael Kölling and David J. Barnes
* @version 2016.02.29
*/
public class Clock
{
private JFrame frame;
private JLabel label;
private ClockDisplay clock;
private boolean clockRunning = false;
private TimerThread timerThread;
/**
* Constructor for objects of class Clock
*/
public Clock()
{
makeFrame();
clock = new ClockDisplay();

8. 8
}
/**
*
*/
private void start()
{
clockRunning = true;
timerThread = new TimerThread();
timerThread.start();
}
/**
*
*/
private void stop()
{
clockRunning = false;
}
/**
*
*/
private void step()
{
clock.timeTick();
label.setText(clock.getTime());
}

9. 9
/**
* 'About' function: show the 'about' box.
*/
private void showAbout()
{
JOptionPane.showMessageDialog (frame,
"Clock Version 1.0n" +
"A simple interface for the 'Objects First' clock display project",
"About Clock",
JOptionPane.INFORMATION_MESSAGE);
}
/**
* Quit function: quit the application.
*/
private void quit()
{
System.exit(0);
}
/**
* Create the Swing frame and its content.
*/
private void makeFrame()
{
frame = new JFrame("Clock");
JPanel contentPane = (JPanel)frame.getContentPane();
contentPane.setBorder(new EmptyBorder(1, 60, 1, 60));

10. 10
makeMenuBar(frame);
// Specify the layout manager with nice spacing
contentPane.setLayout(new BorderLayout(12, 12));
// Create the image pane in the center
label = new JLabel("00:00", SwingConstants.CENTER);
Font displayFont = label.getFont().deriveFont(96.0f);
label.setFont(displayFont);
//imagePanel.setBorder(new EtchedBorder());
contentPane.add(label, BorderLayout.CENTER);
// Create the toolbar with the buttons
JPanel toolbar = new JPanel();
toolbar.setLayout(new GridLayout(1, 0));
JButton startButton = new JButton("Start");
startButton.addActionListener(e -> start());
toolbar.add(startButton);
JButton stopButton = new JButton("Stop");
stopButton.addActionListener(e -> stop());
toolbar.add(stopButton);
JButton stepButton = new JButton("Step");
stepButton.addActionListener(e -> step());
toolbar.add(stepButton);

11. 11
// Add toolbar into panel with flow layout for spacing
JPanel flow = new JPanel();
flow.add(toolbar);
contentPane.add(flow, BorderLayout.SOUTH);
// building is done - arrange the components
frame.pack();
// place the frame at the center of the screen and show
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
frame.setLocation(d.width/2 - frame.getWidth()/2, d.height/2 - frame.getHeight()/2);
frame.setVisible(true);
}
/**
* Create the main frame's menu bar.
*
* @param frame The frame that the menu bar should be added to.
*/
private void makeMenuBar(JFrame frame)
{
final int SHORTCUT_MASK =
Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
JMenuBar menubar = new JMenuBar();
frame.setJMenuBar(menubar);
JMenu menu;

12. 12
JMenuItem item;
// create the File menu
menu = new JMenu("File");
menubar.add(menu);
item = new JMenuItem("About Clock...");
item.addActionListener(e -> showAbout());
menu.add(item);
menu.addSeparator();
item = new JMenuItem("Quit");
item.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_Q, SHORTCUT_MASK));
item.addActionListener(e -> quit());
menu.add(item);
}
class TimerThread extends Thread
{
public void run()
{
while (clockRunning) {
step();
pause();
}
}
private void pause()

13. 13
{
try {
Thread.sleep(300); // pause for 300 milliseconds
}
catch (InterruptedException exc) {
}
}
}
}