02115 Java Programming


02115 Java Programming
Autumn 2011

Week plan #12

For the week 21. November - 25. November

Preparations for the week

Remember to study details of the simplesound project - section 11.9 (pages 376 - 378) of the BK textbook. The SoundPlayerGUI class presents some constructs which might be useful in your implementation of the Mandatory Assignment

Not only exception handling (as suggested on Week plan #11) can be used as a means of turning back user interface independant messages. Those messages at the end has to be shown as text either in a command line interface or in a GUI, e.g. in a message dialogue:

Use exceptions as described on Week plan #11
Introduce error codes, either negative integers or (better) values from an enum class
Make your own class MessageHandler equiped with some public methods to be used when some class needs to turn back test information, normal messages or error messages. When one of your classes needs to turn back messages it just declares it's own private instance of the message handler and thus get access to the methods of that class. This class can be combined with use of enum values

Use of auxiliary methods leads to simpler code.

When e.g. many buttons has to be added auxiliary methods should be declared and used. The idea is introduced based on Code 11.14 of the textbook where two buttons are added to a panel. If many more components should have been added then introduce an auxiliary method:

  private JButton addButton(String text, JPanel toPanel) 
  {
     JButton b = new JButton(text);
     toPanel.add(b);
     return b;
  }

And then we just write these two lines of Java code:

  smallerButton = addButton("Smaller", toolbar);
  largerButton  = addButton("Larger",  toolbar);

to achieve the same as done in Code 11.14 using four lines of Java code:

  smallerButton = new JButton("Smaller");
  toolbar.add(smallerButton);

  largerButton = new JButton("Larger";
  toolbar.add(largerButton);

In our grading of the GUI's to achieve specific functionalities the shorter and more readable the code the higher it will be evaluated. Just because it's about GUI's don't forget to use the principles of object oriented thinking and how to work out well-structured and simple solutions instead of just doing copy and paste followed by editing. Otherwise the result is much duplicated code

The lectures

No lectures

Exercises at the PC's

The exercise session of today starts at 17:00 and ends at 21:00.

The exercise sessions in this week and the next week are dedicated to your work with the Mandatory Assignment. It's important to have refactored the model part of the solution so the same model can be used either with the command line interface or with the GUI

Jens Thyge Kristensen, Email: jtk@imm.dtu.dk

Newest edition: 15. November
Previous editions:
- 8. April (just the heading and the footing)