1. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 1 Outline 18.1 Test-Driving the Microwave Oven Application 18.2 Designing the Microwave Oven Application 18.3 Initializing Objects: Constructors 18.4 Get and Set Methods 18.5 Completing the Microwave Oven Application 18.6 Controlling Access to Members 18.7 The main Method 18.8 Using the Debugger: The watch Command 18.9 Wrap-Up Tutorial 18 – Microwave Oven Application Building Your Own Classes and Objects

2. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 2 Objectives In this tutorial, you will learn to: –Declare your own classes. –Create and use objects of your own classes. –Control access to instance variables. –Use keyword private. –Declare your own get and set methods.

3. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 3 18.1 Test-Driving the Microwave Oven Application

4. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 4 18.1 Test-Driving the Microwave Oven Application (Cont.) Running the completed application –Open a Command Prompt Change to MircowaveOven directory Type java MircowaveOven

5. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 5 18.1 Test-Driving the Microwave Oven Application (Cont.) Figure 18.1 Microwave Oven application GUI displayed when your application is executed. Microwave’s glass window Numeric Keypad

6. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 6 18.1 Test-Driving the Microwave Oven Application (Cont.) Figure 18.2 Microwave Oven application accepts only four digits. Enter test data into application

7. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 7 18.1 Test-Driving the Microwave Oven Application (Cont.) Figure 18.3 Microwave Oven application with invalid input. Microwave doesn’t accept times greater than 60 minutes

8. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 8 18.1 Test-Driving the Microwave Oven Application (Cont.) Figure 18.4 Microwave Oven application after invalid input has been entered and the Start JButton clicked.

9. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 9 18.1 Test-Driving the Microwave Oven Application (Cont.) Figure 18.5 Microwave Oven application with valid time entered and inside light turned on (it’s now cooking). Color yellow simulates microwave light

10. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 10 18.1 Test-Driving the Microwave Oven Application (Cont.) Figure 18.6 Microwave Oven application after the cooking time has elapsed. JTextField displays Done! when cooking has finished Color returns to default color to simulate that cooking has finished

11. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 11 18.2 Designing the Microwave Oven Application When the user clicks a numeric JButton Display the formatted time When the user clicks the Start JButton Display the formatted time Store the minutes and seconds Begin the countdown Turn the microwave light on

12. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 12 18.2 Designing the Microwave Oven Application (Cont.) When the timer ticks (once per second) Decrease the time by one second If the new time is not zero Display the new time Else Stop timer Display the text “Done!” Turn the microwave light off When the user clicks the Clear JButton Stop the countdown Display the text “Microwave Oven” Turn the microwave light off

13. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 13 18.2 Designing the Microwave Oven Application (Cont.)

14. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 14 18.2 Designing the Microwave Oven Application (Cont.)

15. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 15 18.2 Designing the Microwave Oven Application (Cont.) Figure 18.8 Empty class declaration. Empty class declaration. Keyword class indicates that a class declaration follows Members of a class Methods or variables declared within the body of a class

16. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 16 18.2 Designing the Microwave Oven Application (Cont.) Figure 18.9 CookingTime ’s instance variables. Instance variables store minute and second information

17. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 17 18.3 Initializing Objects: Constructors Constructors –Used to initialize instance variables –Has the same name as the class that contains it –Similar to a method Cannot return a value Can take arguments

18. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 18 18.3 Initializing Objects: Constructors (Cont.) Figure 18.10 Declaring an empty constructor. Constructor

19. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 19 18.3 Initializing Objects: Constructors (Cont.) Figure 18.11 Constructor initializing instance variables. Constructor arguments assigned to instance variables Values will be specified for the object in the client of the class.

20. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 20 18.3 Initializing Objects: Constructors (Cont.) Figure 18.12 Declaring an object of type CookingTime. Declaring an instance of class CookingTime Java is an extensible language. Can be extended with new classes.

21. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 21 18.4 Get and Set Methods Access and modify instance variables –Get methods Obtain the value of an instance variable Also called accessors –Set methods Set the value of an instance variable Also called mutators

22. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 22 18.4 Get and Set Methods (Cont.) Maintaining data in a consistent state –Set methods ensure that each instance variable contains a proper value Instance variable minute should only contain values between 0 and 59

23. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 23 18.4 Get and Set Methods (Cont.) Figure 18.13 getMinute declaration. Returning a value from a get method

24. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 24 18.4 Get and Set Methods (Cont.) Figure 18.14 setMinute declaration. Code used to validate data setMinute accepts positive values less than 60.

25. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 25 18.4 Get and Set Methods (Cont.) Figure 18.15 getSecond declaration. Code to return the second value

26. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 26 18.4 Get and Set Methods (Cont.) Figure 18.16 setSecond declaration. Method setSecond is similar to setMinute setSecond accepts positive values less than 60.

27. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 27 18.4 Get and Set Methods (Cont.) Figure 18.17 isDone declaration. Testing whether both minute and second are equal to 0 Returns true if microwave is done cooking, false otherwise

28. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 28 18.4 Get and Set Methods (Cont.) Figure 18.18 Constructor using set methods to initialize variables. Assign data by calling methods setMinute and setSecond Calling set methods ensure that only valid data will be assigned to minute and second.

29. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 29 18.4 Get and Set Methods (Cont.) The this reference –Refer to the current object of the class with the keyword this. –this is automatically added to the method call

30. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 30 18.4 Get and Set Methods (Cont.) Figure 18.19 Decrementing the time in the tick method. Decrementing second Decrementing minute and setting second to 59 Decrements the time by one second. Save your source code file.

31. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 31 18.5 Completing the Microwave Oven Application Figure 18.20 Creating clockTimer with a delay of 1000 milliseconds. Setting clockTimer ’s delay Time is measured in milliseconds.

32. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 32 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.21 Declaring currentTime to hold timeToDisplay value. Copy timeToDisplay into currentTime Make the time output 4 characters long.

33. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 33 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.22 Extracting minutes and seconds from currentTime. Calling two different versions of String method substring Format output as two digits, followed by a colon, followed by two digits.

34. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 34 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.23 Starting the Microwave Oven countdown. Start timer and turn “light” on to indicate microwave oven is cooking

35. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 35 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.24 Clearing the Microwave Oven input. Code that turns off microwave and resets variables

36. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 36 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.25 Appending digit and formatting timeToDisplay. Appending digit to instance variable timeToDisplay Display the data as it is being input

37. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 37 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.26 Modifying the display during countdown. Decrements time during countdown

38. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 38 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.27 Turning off the microwave when the timer runs out. Stopping clockTimer stop method turns off the clockTimer. Reset background color to gray.

39. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 39 18.5 Completing the Microwave Oven Application (Cont.) Figure 18.28 Running the Microwave Oven application. Save the changes to your code Compile and run in the Command Prompt

40. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 40 18.6 Controlling Access to Members Figure 18.29 Declaring CookingTime ’s instance variables as private. Declaring instance variables of class CookingTime, private private data is only accessible to members of the class.

41. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 41 18.6 Controlling Access to Members (Cont.) Figure 18.30 Declaring MicrowaveOven ’s instance variables as private. Declaring instance variables of class MicrowaveOven, private

42. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 42 18.6 Controlling Access to Members (Cont.) Figure 18.31 Declaring the displayTime method as private. Declaring method displayTime of class MicrowaveOven, private

43.  2004 Prentice Hall, Inc. All rights reserved. Outline 43 1 // Tutorial 18: MicrowaveOven.java 2 // Mimics the behavior of a microwave oven. 3 import java.awt.*; 4 import java.awt.event.*; 5 import java.text.DecimalFormat; 6 import javax.swing.*; 7 import javax.swing.border.*; 8 9 public class MicrowaveOven extends JFrame 10 { 11 // JPanel for microwave window 12 private JPanel windowJPanel; 13 14 // JPanel for microwave controls 15 private JPanel controlJPanel; 16 17 // JTextField for cooking time 18 private JTextField displayJTextField; 19 20 // JButtons to set cooking time 21 private JButton oneJButton; 22 private JButton twoJButton; 23 private JButton threeJButton; 24 private JButton fourJButton; 25 private JButton fiveJButton; MicrowaveOven.java (1 of 22)

44.  2004 Prentice Hall, Inc. All rights reserved. Outline 44 26 private JButton sixJButton; 27 private JButton sevenJButton; 28 private JButton eightJButton; 29 private JButton nineJButton; 30 private JButton zeroJButton; 31 32 // JButtons to start and clear timer 33 private JButton startJButton; 34 private JButton clearJButton; 35 36 // Timer to count down seconds 37 private Timer clockTimer; 38 39 // String for storing digits entered by user 40 private String timeToDisplay = ""; 41 42 // CookingTime instance for storing the current time 43 private CookingTime time = new CookingTime( 0, 0 ); 44 45 // DecimalFormat to format time output 46 private DecimalFormat timeFormat = new DecimalFormat( "00" ); MicrowaveOven.java (2 of 22) Declaring instance variable timeToDisplay private Declaring instance variable cookingTime private

45.  2004 Prentice Hall, Inc. All rights reserved. Outline 45 47 48 // no-argument constructor 49 public MicrowaveOven() 50 { 51 createUserInterface(); 52 } 53 54 // create and position GUI components; register event handlers 55 private void createUserInterface() 56 { 57 // get content pane for attaching GUI components 58 Container contentPane = getContentPane(); 59 60 // enable explicit positioning of GUI components 61 contentPane.setLayout( null ); 62 63 // set up windowJPanel 64 windowJPanel = new JPanel(); 65 windowJPanel.setBounds( 16, 16, 328, 205 ); 66 windowJPanel.setBorder( new LineBorder( Color.BLACK ) ); 67 contentPane.add( windowJPanel ); 68 MicrowaveOven.java (3 of 22)

46.  2004 Prentice Hall, Inc. All rights reserved. Outline 46 69 // set up controlJPanel 70 controlJPanel = new JPanel(); 71 controlJPanel.setBounds( 368, 16, 149, 205 ); 72 controlJPanel.setBorder( new LineBorder( Color.BLACK ) ); 73 controlJPanel.setLayout( null ); 74 contentPane.add( controlJPanel ); 75 76 // set up displayJTextField 77 displayJTextField = new JTextField(); 78 displayJTextField.setBounds( 7, 5, 135, 42 ); 79 displayJTextField.setText( "Microwave Oven" ); 80 displayJTextField.setHorizontalAlignment( JTextField.CENTER ); 81 displayJTextField.setEditable( false ); 82 controlJPanel.add( displayJTextField ); 83 84 // set up oneJButton 85 oneJButton = new JButton(); 86 oneJButton.setBounds( 13, 59, 41, 24 ); 87 oneJButton.setText( "1" ); 88 controlJPanel.add( oneJButton ); 89 oneJButton.addActionListener( 90 MicrowaveOven.java (4 of 22)

47.  2004 Prentice Hall, Inc. All rights reserved. Outline 47 91 new ActionListener() // anonymous inner class 92 { 93 // event handler called when oneJButton is pressed 94 public void actionPerformed( ActionEvent event ) 95 { 96 oneJButtonActionPerformed( event ); 97 } 98 99 } // end anonymous inner class 100 101 ); // end call to addActionListener 102 103 // set up twoJButton 104 twoJButton = new JButton(); 105 twoJButton.setBounds( 54, 59, 41, 24 ); 106 twoJButton.setText( "2" ); 107 controlJPanel.add( twoJButton ); 108 twoJButton.addActionListener( 109 110 new ActionListener() // anonymous inner class 111 { 112 // event handler called when twoJButton is pressed MicrowaveOven.java (5 of 22)

48.  2004 Prentice Hall, Inc. All rights reserved. Outline 48 113 public void actionPerformed( ActionEvent event ) 114 { 115 twoJButtonActionPerformed( event ); 116 } 117 118 } // end anonymous inner class 119 120 ); // end call to addActionListener 121 122 // set up threeJButton 123 threeJButton = new JButton(); 124 threeJButton.setBounds( 95, 59, 41, 24 ); 125 threeJButton.setText( "3" ); 126 controlJPanel.add( threeJButton ); 127 threeJButton.addActionListener( 128 129 new ActionListener() // anonymous inner class 130 { 131 // event handler called when threeJButton is pressed 132 public void actionPerformed( ActionEvent event ) 133 { 134 threeJButtonActionPerformed( event ); 135 } 136 137 } // end anonymous inner class MicrowaveOven.java (6 of 22)

49.  2004 Prentice Hall, Inc. All rights reserved. Outline 49 138 139 ); // end call to addActionListener 140 141 // set up fourJButton 142 fourJButton = new JButton(); 143 fourJButton.setBounds( 13, 83, 41, 24 ); 144 fourJButton.setText( "4" ); 145 controlJPanel.add( fourJButton ); 146 fourJButton.addActionListener( 147 148 new ActionListener() // anonymous inner class 149 { 150 // event handler called when fourJButton is pressed 151 public void actionPerformed( ActionEvent event ) 152 { 153 fourJButtonActionPerformed( event ); 154 } 155 156 } // end anonymous inner class 157 158 ); // end call to addActionListener 159 MicrowaveOven.java (7 of 22)

50.  2004 Prentice Hall, Inc. All rights reserved. Outline 50 160 // set up fiveJButton 161 fiveJButton = new JButton(); 162 fiveJButton.setBounds( 54, 83, 41, 24 ); 163 fiveJButton.setText( "5" ); 164 controlJPanel.add( fiveJButton ); 165 fiveJButton.addActionListener( 166 167 new ActionListener() // anonymous inner class 168 { 169 // event handler called when fiveJButton is pressed 170 public void actionPerformed( ActionEvent event ) 171 { 172 fiveJButtonActionPerformed( event ); 173 } 174 175 } // end anonymous inner class 176 177 ); // end call to addActionListener 178 179 // set up sixJButton 180 sixJButton = new JButton(); 181 sixJButton.setBounds( 95, 83, 41, 24 ); 182 sixJButton.setText( "6" ); 183 controlJPanel.add( sixJButton ); 184 sixJButton.addActionListener( MicrowaveOven.java (8 of 22)

51.  2004 Prentice Hall, Inc. All rights reserved. Outline 51 185 186 new ActionListener() // anonymous inner class 187 { 188 // event handler called when sixJButton is pressed 189 public void actionPerformed( ActionEvent event ) 190 { 191 sixJButtonActionPerformed( event ); 192 } 193 194 } // end anonymous inner class 195 196 ); // end call to addActionListener 197 198 // set up sevenJButton 199 sevenJButton = new JButton(); 200 sevenJButton.setBounds( 13, 107, 41, 24 ); 201 sevenJButton.setText( "7" ); 202 controlJPanel.add( sevenJButton ); 203 sevenJButton.addActionListener( 204 205 new ActionListener() // anonymous inner class 206 { 207 // event handler called when sevenJButton is pressed MicrowaveOven.java (9 of 22)

52.  2004 Prentice Hall, Inc. All rights reserved. Outline 52 208 public void actionPerformed( ActionEvent event ) 209 { 210 sevenJButtonActionPerformed( event ); 211 } 212 213 } // end anonymous inner class 214 215 ); // end call to addActionListener 216 217 // set up eightJButton 218 eightJButton = new JButton(); 219 eightJButton.setBounds( 54, 107, 41, 24 ); 220 eightJButton.setText( "8" ); 221 controlJPanel.add( eightJButton ); 222 eightJButton.addActionListener( 223 224 new ActionListener() // anonymous inner class 225 { 226 // event handler called when eightJButton is pressed 227 public void actionPerformed( ActionEvent event ) 228 { 229 eightJButtonActionPerformed( event ); 230 } 231 232 } // end anonymous inner class MicrowaveOven.java (10 of 22)

53.  2004 Prentice Hall, Inc. All rights reserved. Outline 53 233 234 ); // end call to addActionListener 235 236 // set up nineJButton 237 nineJButton = new JButton(); 238 nineJButton.setBounds( 95, 107, 41, 24 ); 239 nineJButton.setText( "9" ); 240 controlJPanel.add( nineJButton ); 241 nineJButton.addActionListener( 242 243 new ActionListener() // anonymous inner class 244 { 245 // event handler called when nineJButton is pressed 246 public void actionPerformed( ActionEvent event ) 247 { 248 nineJButtonActionPerformed( event ); 249 } 250 251 } // end anonymous inner class 252 253 ); // end call to addActionListener 254 MicrowaveOven.java (11 of 22)

54.  2004 Prentice Hall, Inc. All rights reserved. Outline 54 255 // set up zeroJButton 256 zeroJButton = new JButton(); 257 zeroJButton.setBounds( 54, 131, 41, 24 ); 258 zeroJButton.setText( "0" ); 259 controlJPanel.add( zeroJButton ); 260 zeroJButton.addActionListener( 261 262 new ActionListener() // anonymous inner class 263 { 264 // event handler called when zeroJButton is pressed 265 public void actionPerformed( ActionEvent event ) 266 { 267 zeroJButtonActionPerformed( event ); 268 } 269 270 } // end anonymous inner class 271 272 ); // end call to addActionListener 273 274 // set up startJButton 275 startJButton = new JButton(); 276 startJButton.setBounds( 7, 171, 64, 24 ); 277 startJButton.setText( "Start" ); 278 controlJPanel.add( startJButton ); 279 startJButton.addActionListener( MicrowaveOven.java (12 of 22)

55.  2004 Prentice Hall, Inc. All rights reserved. Outline 55 280 281 new ActionListener() // anonymous inner class 282 { 283 // event handler called when startJButton is pressed 284 public void actionPerformed( ActionEvent event ) 285 { 286 startJButtonActionPerformed( event ); 287 } 288 289 } // end anonymous inner class 290 291 ); // end call to addActionListener 292 293 // set up clearJButton 294 clearJButton = new JButton(); 295 clearJButton.setBounds( 79, 171, 64, 24 ); 296 clearJButton.setText( "Clear" ); 297 controlJPanel.add( clearJButton ); 298 clearJButton.addActionListener( 299 300 new ActionListener() // anonymous inner class 301 { 302 // event handler called when clearJButton is pressed MicrowaveOven.java (13 of 22)

56.  2004 Prentice Hall, Inc. All rights reserved. Outline 56 303 public void actionPerformed( ActionEvent event ) 304 { 305 clearJButtonActionPerformed( event ); 306 } 307 308 } // end anonymous inner class 309 310 ); // end call to addActionListener 311 312 // set up timerActionListener 313 ActionListener timerListener = 314 315 new ActionListener() // anonymous inner class 316 { 317 // event handler called every 1000 milliseconds 318 public void actionPerformed( ActionEvent event ) 319 { 320 clockTimerActionPerformed( event ); 321 } 322 323 }; // end anonymous inner class 324 325 // set up clockTimer 326 clockTimer = new Timer( 1000, timerActionListener ); 327 MicrowaveOven.java (14 of 22)

57.  2004 Prentice Hall, Inc. All rights reserved. Outline 57 328 // set properties of application ’ s window 329 setTitle( "Microwave Oven" ); // set title-bar string 330 setSize( 536, 261 ); // set window size 331 setVisible( true ); // display window 332 333 } // end method createUserInterface 334 335 // add digit 1 to timeToDisplay 336 private void oneJButtonActionPerformed( ActionEvent event ) 337 { 338 displayTime( "1" ); // display time input properly 339 340 } // end method oneJButtonActionPerformed 341 342 // add digit 2 to timeToDisplay 343 private void twoJButtonActionPerformed( ActionEvent event ) 344 { 345 displayTime( "2" ); // display time input properly 346 347 } // end method twoJButtonActionPerformed 348 MicrowaveOven.java (15 of 22)

58.  2004 Prentice Hall, Inc. All rights reserved. Outline 58 349 // add digit 3 to timeToDisplay 350 private void threeJButtonActionPerformed( ActionEvent event ) 351 { 352 displayTime( "3" ); // display time input properly 353 354 } // end method threeJButtonActionPerformed 355 356 // add digit 4 to timeToDisplay 357 private void fourJButtonActionPerformed( ActionEvent event ) 358 { 359 displayTime( "4" ); // display time input properly 360 361 } // end method fourJButtonActionPerformed 362 363 // add digit 5 to timeToDisplay 364 private void fiveJButtonActionPerformed( ActionEvent event ) 365 { 366 displayTime( "5" ); // display time input properly 367 368 } // end method fiveJButtonActionPerformed 369 370 // add digit 6 to timeToDisplay 371 private void sixJButtonActionPerformed( ActionEvent event ) 372 { 373 displayTime( "6" ); // display time input properly MicrowaveOven.java (16 of 22)

59.  2004 Prentice Hall, Inc. All rights reserved. Outline 59 374 375 } // end method sixJButtonActionPerformed 376 377 // add digit 7 to timeToDisplay 378 private void sevenJButtonActionPerformed( ActionEvent event ) 379 { 380 displayTime( "7" ); // display time input properly 381 382 } // end method sevenJButtonActionPerformed 383 384 // add digit 8 to timeToDisplay 385 private void eightJButtonActionPerformed( ActionEvent event ) 386 { 387 displayTime( "8" ); // display time input properly 388 389 } // end method eightJButtonActionPerformed 390 391 // add digit 9 to timeToDisplay 392 private void nineJButtonActionPerformed( ActionEvent event ) 393 { 394 displayTime( "9" ); // display time input properly 395 396 } // end method nineJButtonActionPerformed 397 MicrowaveOven.java (17 of 22)

60.  2004 Prentice Hall, Inc. All rights reserved. Outline 60 398 // add digit 0 to timeToDisplay 399 private void zeroJButtonActionPerformed( ActionEvent event ) 400 { 401 displayTime( "0" ); // display time input properly 402 403 } // end method zeroJButtonActionPerformed 404 405 // format the time so that it has exactly four digits 406 private String formatTime() 407 { 408 // declare String currentTime to manipulate output 409 String currentTime = timeToDisplay; 410 411 // add zeros to currentTime until it is 4 characters long 412 for ( int i = currentTime.length(); i < 4; i++ ) 413 { 414 currentTime = "0" + currentTime; 415 } 416 417 // if the length of currentTime is greater than four 418 if ( currentTime.length() > 4 ) 419 { 420 // shorten currentTime to the first four characters 421 currentTime = currentTime.substring( 0, 4 ); 422 } MicrowaveOven.java (18 of 22) Lengthening the time, if necessary Shortening the time, if necessary

61.  2004 Prentice Hall, Inc. All rights reserved. Outline 61 423 424 return currentTime; 425 426 } // end method formatTime 427 428 // start the microwave oven 429 private void startJButtonActionPerformed( ActionEvent event ) 430 { 431 // get the time as four digits 432 String fourDigitTime = formatTime(); 433 434 // extract seconds and minutes 435 String minute = fourDigitTime.substring( 0, 2 ); 436 String second = fourDigitTime.substring( 2 ); 437 438 // initialize CookingTime object to time entered by user 439 microwaveTime.setMinute( Integer.parseInt( minute ) ); 440 microwaveTime.setSecond( Integer.parseInt( second ) ); 441 442 // display starting time in displayJTextField 443 displayJTextField.setText( timeFormat.format( 444 microwaveTime.getMinute() ) + ":" + timeFormat.format( 445 microwaveTime.getSecond() ) ); 446 447 timeToDisplay = 0; // clear timeToDisplay for future input MicrowaveOven.java (19 of 22) Storing the time as exactly four digits Obtaining the minutes and seconds Setting the minutes and seconds for the cooking time Displaying the starting cooking time

62.  2004 Prentice Hall, Inc. All rights reserved. Outline 62 448 449 clockTimer.start(); // start timer 450 windowJPanel.setBackground( Color.YELLOW ); // turn "light" on 451 452 } // end method startJButtonActionPerformed 453 454 // clear the microwave oven 455 private void clearJButtonActionPerformed( ActionEvent event ) 456 { 457 // stop Timer and reset variables to their initial settings 458 clockTimer.stop(); 459 displayJTextField.setText( "Microwave Oven" ); 460 timeToDisplay = ""; 461 windowJPanel.setBackground( new Color( 204, 204, 204 ) ); 462 463 } // end method clearJButtonActionPerformed 464 465 // display formatted time in displayJTextField 466 private void displayTime( String digit ) 467 { 468 // append digit to timeToDisplay 469 timeToDisplay += digit; 470 471 // get the time as four digits 472 String fourDigitTime = formatTime(); MicrowaveOven.java (20 of 22) Starting the microwave Stopping the microwave and clearing the cooking time Adding a digit to a timeStoring the time as exactly four digits

63.  2004 Prentice Hall, Inc. All rights reserved. Outline 63 473 474 // extract seconds and minutes 475 String minute = fourDigitTime.substring( 0, 2 ); 476 String second = fourDigitTime.substring( 2 ); 477 478 // display number of minutes, ":", and then number of seconds 479 displayJTextField.setText( minute + ":" + second ); 480 481 } // end method displayTime 482 483 // decrement displayJTextField by one second 484 private void clockTimerActionPerformed( ActionEvent event ) 485 { 486 // decrement time by one second 487 time.tick(); 488 489 // if time has not reached zero 490 if ( !time.isDone() ) 491 { 492 // display remaining cooking time in displayJTextField 493 displayJTextField.setText( timeFormat.format( 494 time.getMinute() ) + ":" + timeFormat.format( 495 time.getSecond() ) ); 496 497 } // end if MicrowaveOven.java (21 of 22) Obtaining the minutes and seconds Outputting the formatted time Decrementing the cooking time Displaying the remaining cooking time

64.  2004 Prentice Hall, Inc. All rights reserved. Outline 64 498 else // time has reached zero 499 { 500 clockTimer.stop(); // stop timer 501 502 // inform user timer is finished 503 displayJTextField.setText( "Done!" ); 504 windowJPanel.setBackground( new Color( 204, 204, 204 ) ); 505 506 } // end else 507 508 } // end method clockTimerActionPerformed 509 510 // main method 511 public static void main( String args[] ) 512 { 513 MicrowaveOven application = new MicrowaveOven(); 514 application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE ); 515 516 } // end method main 517 518 } // end class MicrowaveOven MicrowaveOven.java (22 of 22) Stopping the microwave Notifying the user that the microwave has stopped

65.  2004 Prentice Hall, Inc. All rights reserved. Outline 65 1 // Tutorial 18: CookingTime.java 2 // Represents time data and contains get and set methods. 3 4 public class CookingTime 5 { 6 // integers for storing minutes and seconds 7 private int minute; 8 private int second; 9 10 // CookingTime constructor, minute and second supplied 11 public CookingTime( int minuteValue, int secondValue ) 12 { 13 setMinute( minuteValue ); 14 setSecond( secondValue ); 15 16 } // end constructor 17 18 // return minute value 19 public int getMinute() 20 { 21 return minute; 22 23 } // end method getMinute 24 CookingTime.java (1 of 4) Declaring instance variables of class CookingTime private Construcor of class CookingTime Returning value of instance variable minute

66.  2004 Prentice Hall, Inc. All rights reserved. Outline 66 25 // set minute value 26 public void setMinute( int value ) 27 { 28 if ( value >= 0 && value < 60 ) 29 { 30 minute = value; // minute is valid 31 } 32 else 33 { 34 minute = 0; // set invalid input to 0 35 } 36 37 } // end method setMinute 38 39 // return second value 40 public int getSecond() 41 { 42 return second; 43 44 } // end method getSecond 45 CookingTime.java (2 of 4) Validating user input for instance variable minute Returning value of instance variable second

67.  2004 Prentice Hall, Inc. All rights reserved. Outline 67 46 // set second value 47 public void setSecond( int value ) 48 { 49 if ( value >= 0 && value < 60 ) 50 { 51 second = value; // second is valid 52 } 53 else 54 { 55 second = 0; // set invalid input to 0 56 } 57 58 } // end method setSecond 59 60 // return whether or not the time has reached zero 61 public boolean isDone() 62 { 63 return ( minute == 0 && second == 0 ); 64 65 } // end method isDone 66 CookingTime.java (3 of 4) Validating user input for instance variable second Testing whether minute and second are both equal to 0

68.  2004 Prentice Hall, Inc. All rights reserved. Outline 68 67 // decrement the time by one second 68 public void tick() 69 { 70 // handle case when seconds need to be decremented 71 if ( getSecond() > 0 ) 72 { 73 setSecond( getSecond() - 1 ); // subtract one second 74 } 75 // handle case when minutes must be decremented 76 else if ( getMinute() > 0 ) 77 { 78 setMinute( getMinute() - 1 ); // subtract one minute 79 setSecond( 59 ); // set seconds to 59 80 } 81 82 } // end method tick 83 84 } // end class CookingTime CookingTime.java (4 of 4) Decrementing minute and setting second to 59 Decrementing second

69. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 69 18.7 The main Method Figure 18.34 Method header for the main method. main is declared static Calling MicrowaveOven ’s constructor main method is the entry point of the application always declared static

70. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 70 18.7 The main Method (Cont.) Figure 18.35 Constructor calling the createUserInterface method. Calling method createUserInterface

71. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 71 18.8 Using the Debugger: The watch Command Figure 18.36 Setting a watch on CookingTime ’s instance variable second. Setting a watch

72. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 72 18.8 Using the Debugger: The watch Command (Cont.) Figure 18.37 Microwave Oven application stops when microwaveTime is created. Debugger notifying you when the value changes

73. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 73 18.8 Using the Debugger: The watch Command (Cont.) Figure 18.38 Changing the value of second by starting the microwave.

74. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 74 18.8 Using the Debugger: The watch Command (Cont.) Figure 18.39 Notifying the user of a change in the value of second.

75. © Copyright 1992-2004 by Deitel & Associates, Inc. and Pearson Education Inc. All Rights Reserved. 75 18.8 Using the Debugger: The watch Command (Cont.) Figure 18.40 Removing the watch. Removing the watch from an instance variable