Contoh Event Handling di Java

Event Handling merupakan konsep penanganan suatu action yang terjadi. Jadi suatu program akan berjalan saat sesuatu terjadi, misalnya saat tombol diklik, saat combo box dipilih dan sebagainya. Java memiliki beberapa jenis Event Handling, salah satunya adalah class ActionListener yang menangani aksi terhadap tombol. Berikut ini contoh programnya:
Tampilan:


Program:

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01	import java.awt.*;

02	import java.awt.event.*;

03	import javax.swing.*;

04

05	public class ClickMe extends JFrame implements ActionListener {

06	private JButton tombol;

07

08	public ClickMe() {

09	super ("Event Handling");

10

11	Container container = getContentPane();

12	container.setLayout(new FlowLayout());

13

14	tombol = new JButton ("Click Me!");

15	tombol.addActionListener(this);

16	container.add(tombol);

17

18	setSize (200,100);

19	setVisible (true);

20

}

21

22	public static void main (String arg[]) {

23	ClickMe test = new ClickMe();

24	test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

25

}

26

27	public void actionPerformed (ActionEvent e) {

28	if (e.getSource() == tombol) {

29	JOptionPane.showMessageDialog(null, "You click me, guys !!!");

30

}

31

}

32

}

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Contoh Program Event Handling di Java (2)

Contoh program berikut ini pada dasarnya sama dengan contoh program sebelumnya. Hanya saja pada contoh kali ini, ditambahkan tombol Exit yang jika diklik program akan keluar.
Berikut ini tampilannya:

Berikut ini programnya:

01	import java.awt.*;

02

03	import java.awt.event.*;

04

05	import javax.swing.*;

06

07	public class ClickMe2 extends JFrame {

08

09	private JButton tombol, btnExit;

10

11	public ClickMe2() {

12

13	super ("Event Handling");

14

15	Container container = getContentPane();

16

17	container.setLayout(new FlowLayout());

18

19	ClickListener cl = new ClickListener ();

20

21	tombol = new JButton ("Click Me!");

22

23	tombol.addActionListener(cl);

24

25	container.add(tombol);

26

27	btnExit = new JButton ("Exit");

28

29	btnExit.addActionListener(cl);

30

31	container.add(btnExit);

32

33	setSize (200,100);

34

35	setVisible (true);

36

37

}

38

39	public static void main (String arg[]) {

40

41	ClickMe2 test = new ClickMe2();

42

43	test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

44

45

}

46

47	//inner class

48

49	private class ClickListener implements ActionListener {

50

51	public void actionPerformed (ActionEvent e) {

52

53	if (e.getSource() == tombol) {

54

55	JOptionPane.showMessageDialog(null, "You click me again, guys !!!");

56

57	} else if (e.getSource() == btnExit){

58

59	JOptionPane.showMessageDialog(null, "See you, guys !");

60

61	System.exit(0);

62

63

}

64

65

}

66

67

}

68

69

}

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Contoh Program Event Handling di Java (3)

Posted at November 5, 2010

Pada contoh berikut ini ditambahkan window konfirmasi saat tombol exit ditekan.
Berikut ini tampilannya:


Contoh program:

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01	import java.awt.*;

02

03	import java.awt.event.*;

04

05	import javax.swing.*;

06

07	public class ClickMe3 extends JFrame {

08

09	private JButton tombol, btnExit;

10

11	public ClickMe3() {

12

13	super ("Event Handling");

14

15	Container container = getContentPane();

16

17	container.setLayout(new FlowLayout());

18

19	ClickListener cl = new ClickListener ();

20

21	tombol = new JButton ("Click Me!");

22

23	tombol.addActionListener(cl);

24

25	container.add(tombol);

26

27	btnExit = new JButton ("Exit");

28

29	btnExit.addActionListener(cl);

30

31	container.add(btnExit);

32

33	setSize (200,100);

34

35	setVisible (true);

36

37

}

38

39	public static void main (String arg[]) {

40

41	ClickMe3 test = new ClickMe3();

42

43	test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

44

45

}

46

47	//inner class

48

49	private class ClickListener implements ActionListener {

50

51	public void actionPerformed (ActionEvent e) {

52

53	if (e.getSource() == tombol) {

54

55	JOptionPane.showMessageDialog(null, "You click me again, guys !!!");

56

57	} else if (e.getSource() == btnExit){

58

59	if ( JOptionPane.showConfirmDialog(null, "Apakah Anda yakin akan keluar ?","Konfirmasi",

60

61	JOptionPane.OK_CANCEL_OPTION,JOptionPane.QUESTION_MESSAGE) == JOptionPane.OK_OPTION) {

62

63	System.exit(0);

64

65

}

66

67

}

68

69

}

70

71

}

72

73

}

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Contoh Program KeyEvent di Java

Berikut ini contoh program Java untuk mendemonstrasikan bagaimana penanganan event terkait tombol. Program akan mendeteksi penekanan setiap tombol keyboard. Class Listener yang digunakan adalah KeyListener yang memiliki 3 (tiga) buah method abstract keyTyped(), keyPressed() dan keyReleased().
Berikut ini tampilannya:


Dan berikut ini program lengkapnya

01	import java.awt.*;

02	import java.awt.event.*;

03	import javax.swing.*;

04

05	public class KeyEventTest extends JFrame implements KeyListener {

06	private String baris1="", baris2="", baris3="";

07	private JTextArea textArea;

08

09	public KeyEventTest() {

10	super ("Mencoba Key Event");

11

12	textArea = new JTextArea (10,15);

13	textArea.setText("Tekan sembarang tombol di keyboard...");

14	textArea.setEnabled(false);

15	textArea.setDisabledTextColor(Color.BLACK);

16	getContentPane().add(textArea);

17

18	addKeyListener (this);

19

20	setSize (300,150);

21	setLocationRelativeTo(null);

22	setVisible(true);

23

}

24

25	public void keyPressed (KeyEvent e) {

26	baris1 = "Tombol yang ditekan : " + e.getKeyText(e.getKeyCode());

27	setLines2and3 (e);

28

}

29

30	public void keyReleased (KeyEvent e) {

31	baris1 = "Tombol yang dilepas : " + e.getKeyText(e.getKeyCode());

32	setLines2and3 (e);

33

}

34

35	public void keyTyped (KeyEvent e) {

36	baris1 = "Tombol yang ditulis : " + e.getKeyChar();

37	setLines2and3 (e);

38

}

39

40	private void setLines2and3 (KeyEvent e) {

41	baris2 = "This key is "+ (e.isActionKey() ? "" : "not ") + "an action key";

42	String temp = e.getKeyModifiersText(e.getModifiers());

43	baris3 = "Modifier key pressed : " + (temp.equals("") ? "none" : temp);

44	textArea.setText(baris1 + "\n" + baris2 + "\n" + baris3 + "\n");

45

}

46

47	public static void main (String args[]) {

48	KeyEventTest test = new KeyEventTest();

49	test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

50

}

51

}

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Window Event di Java

Contoh program berikut ini memberikan contoh bagaimana penanganan event di dalam window. Event akan aktif saat window diubah ukurannnya, diclose, aktif, dan sebagainya. Listener yang digunakan dalam contoh program ini adalah WindowListener, WindowFocusListener dan WindowStateListener.
Berikut ini tampilannya:


Berikut ini program lengkapnya:

001

/*

002	* WindowEventDemo.java is a 1.4 example that requires

003	* no other files.

004

*/

005

006	import javax.swing.*;

007	import java.awt.*;

008	import java.awt.event.*;

009

010	public class WindowEventDemo extends JPanel

011	implements WindowListener,

012	WindowFocusListener,

013	WindowStateListener {

014	final static String newline = "\n";

015	final static String space = "    ";

016	static JFrame frame;

017	JTextArea display;

018

019	public WindowEventDemo() {

020	super(new BorderLayout());

021	display = new JTextArea();

022	display.setEditable(false);

023	JScrollPane scrollPane = new JScrollPane(display);

024	scrollPane.setPreferredSize(new Dimension(500, 450));

025	add(scrollPane, BorderLayout.CENTER);

026

027	frame.addWindowListener(this);

028	frame.addWindowFocusListener(this);

029	frame.addWindowStateListener(this);

030

031	checkWM();

032

}

033

034	//Some window managers don't support all window states.

035	//For example, dtwm doesn't support true maximization,

036	//but mimics it by resizing the window to be the size

037	//of the screen.  In this case the window does not fire

038	//the MAXIMIZED_ constants on the window's state listener.

039	//Microsoft Windows supports MAXIMIZED_BOTH, but not

040	//MAXIMIZED_VERT or MAXIMIZED_HORIZ.

041	public void checkWM() {

042	Toolkit tk = frame.getToolkit();

043	if (!(tk.isFrameStateSupported(Frame.ICONIFIED))) {

044	displayMessage(

045	"Your window manager doesn't support ICONIFIED.");

046

}

047	if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_VERT))) {

048	displayMessage(

049	"Your window manager doesn't support MAXIMIZED_VERT.");

050

}

051	if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_HORIZ))) {

052	displayMessage(

053	"Your window manager doesn't support MAXIMIZED_HORIZ.");

054

}

055	if (!(tk.isFrameStateSupported(Frame.MAXIMIZED_BOTH))) {

056	displayMessage(

057	"Your window manager doesn't support MAXIMIZED_BOTH.");

058

} else {

059	displayMessage(

060	"Your window manager supports MAXIMIZED_BOTH.");

061

}

062

}

063

064	public void windowClosing(WindowEvent e) {

065	displayMessage("WindowListener method called: windowClosing.");

066

067	//A pause so user can see the message before

068	//the window actually closes.

069	ActionListener task = new ActionListener() {

070	boolean alreadyDisposed = false;

071	public void actionPerformed(ActionEvent e) {

072	if (!alreadyDisposed) {

073	alreadyDisposed = true;

074	frame.dispose();

075	} else { //make sure the program exits

076	System.exit(0);

077

}

078

}

079

};

080	Timer timer = new Timer(500, task); //fire every half second

081	timer.setInitialDelay(2000);        //first delay 2 seconds

082	timer.start();

083

}

084

085	public void windowClosed(WindowEvent e) {

086	//This will only be seen on standard output.

087	displayMessage("WindowListener method called: windowClosed.");

088

}

089

090	public void windowOpened(WindowEvent e) {

091	displayMessage("WindowListener method called: windowOpened.");

092

}

093

094	public void windowIconified(WindowEvent e) {

095	displayMessage("WindowListener method called: windowIconified.");

096

}

097

098	public void windowDeiconified(WindowEvent e) {

099	displayMessage("WindowListener method called: windowDeiconified.");

100

}

101

102	public void windowActivated(WindowEvent e) {

103	displayMessage("WindowListener method called: windowActivated.");

104

}

105

106	public void windowDeactivated(WindowEvent e) {

107	displayMessage("WindowListener method called: windowDeactivated.");

108

}

109

110	public void windowGainedFocus(WindowEvent e) {

111	displayMessage("WindowFocusListener method called: windowGainedFocus.");

112

}

113

114	public void windowLostFocus(WindowEvent e) {

115	displayMessage("WindowFocusListener method called: windowLostFocus.");

116

}

117

118	public void windowStateChanged(WindowEvent e) {

119	displayStateMessage(

120	"WindowStateListener method called: windowStateChanged.", e);

121

}

122

123	void displayMessage(String msg) {

124	display.append(msg + newline);

125	System.out.println(msg);

126

}

127

128	void displayStateMessage(String prefix, WindowEvent e) {

129	int state = e.getNewState();

130	int oldState = e.getOldState();

131	String msg = prefix

132	+ newline + space

133	+ "New state: "

134	+ convertStateToString(state)

135	+ newline + space

136	+ "Old state: "

137	+ convertStateToString(oldState);

138	display.append(msg + newline);

139	System.out.println(msg);

140

}

141

142	String convertStateToString(int state) {

143	if (state == Frame.NORMAL) {

144	return "NORMAL";

145

}

146	if ((state & Frame.ICONIFIED) != 0) {

147	return "ICONIFIED";

148

}

149	//MAXIMIZED_BOTH is a concatenation of two bits, so

150	//we need to test for an exact match.

151	if ((state & Frame.MAXIMIZED_BOTH) == Frame.MAXIMIZED_BOTH) {

152	return "MAXIMIZED_BOTH";

153

}

154	if ((state & Frame.MAXIMIZED_VERT) != 0) {

155	return "MAXIMIZED_VERT";

156

}

157	if ((state & Frame.MAXIMIZED_HORIZ) != 0) {

158	return "MAXIMIZED_HORIZ";

159

}

160	return "UNKNOWN";

161

}

162

163

/**

164	* Create the GUI and show it.  For thread safety,

165	* this method should be invoked from the

166	* event-dispatching thread.

167

*/

168	private static void createAndShowGUI() {

169	//Make sure we have nice window decorations.

170	JFrame.setDefaultLookAndFeelDecorated(true);

171

172	//Create and set up the window.

173	frame = new JFrame("WindowEventDemo");

174	frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);

175

176	//Create and set up the content pane.

177	JComponent newContentPane = new WindowEventDemo();

178	newContentPane.setOpaque(true); //content panes must be opaque

179	frame.setContentPane(newContentPane);

180

181	//Display the window.

182	frame.pack();

183	frame.setVisible(true);

184

}

185

186	public static void main(String[] args) {

187	//Schedule a job for the event-dispatching thread:

188	//creating and showing this application's GUI.

189	javax.swing.SwingUtilities.invokeLater(new Runnable() {

190	public void run() {

191	createAndShowGUI();

192

}

193

});

194

}

195

}

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