PV168

Swing

Where did the second seminar pain come from?

You were solving high-level problems with too much low-level tools
You were missing the appropriate abstractions for your tasks!

Abstraction

The essence of abstractions is preserving information that is relevant in a given context, and forgetting information that is irrelevant in that context. [1]

Real Life Abstractions

Cars
- Steering wheel
- Pedals (brake and throttle)
Electronic devices
- Plug
- Socket

Abstractions you were missing

Java Swing Action
- Substitute for menu items and toolbar buttons
Our own Column (for Swing TableModel)
- Shields us from Repeated Switches problem

The key is to have just enough of it

Too little abstraction
- You experienced it during the second seminar
- Requires heavy copy & paste and leads to many errors
Too much (or wrong) abstraction
- You will likely experience it in your projects
- Too many moving parts leads to great deal of confusion

Java Swing

Java Swing

Added to Java in 1.2
Built on top of AWT (Abstract Window Toolkit) which is Java 1.0
Desktop applications are not web applications!!!
They can be very complex and even look good
- A prominent example built on top of Swing/AWT is IntelliJ IDEA

Windows and Containers

JFrame vs. JDialog
- Use JFrame for the part of your program that is always visible
- Use JDialog’s pop up when you need them, and disappear when you don’t
JPanel is also useful
- Use JPanel as a container for your elements when you have more of them …
- …and you need to have the full control over their layout

JFrame

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Fully-functional top-level window
- Resizeable
- With pull-down menus
- Typically with toolbars
Default layout manager
- BorderLayout

JDialog

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Pop up window
- Positioned relatively to a parent window
- Fixed size
- No menus or toolbars
- Default button
- Closes on Esc

JDialog (cont…)

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Typically modal
- Underlying windows cannot get user input
Typically used via JOptionPane and JPanel

Menus

JMenuBar + JMenu for application menu bar and pull-down menus
- Use JMenuBar for the application menu bar
- Add JMenu for each pull-down menu
JPopupMenu for pup-up menus displayed on right mouse click

JMenuItem for standard menu item (text + icon)
JCheckBoxMenuItem for menu items with a checkbox
JRadioButtonMenuItem for menu items with a radio button

Toolbars

JToolbar as a container of JButton objects

Buttons

JButton as a standard button (text + icon)
JCheckBox for two-state buttons with a check box
JRadioButton for two-state buttons with a radio button
- Note however that radio buttons only make sense in groups

Text Fields

JLabel for displaying a non-editable text
- Very useful especially in dialogs
JTextField for entering a single line of text
JPasswordField for entering a password
JTextArea for entering multiple lines of text
- Has to be wrapped inside JScrollPane to work correctly for large content

Numerical Fields

JSpinner for entering a number
- from an ordered sequence
JSlider for selecting a value graphically
- from an interval

Date Fields

DatePicker for selecting a calendar date

Unfortunately this component comes from 3^rd party
- We are using com.github.lgooddatepicker

List, Tables, and Trees

JList for a visualizing a list of simple values (single column)
- The collapsed version with only a single value shown is JComboBox
JTable for visualizing a list of compound values (matrix)
JTree for visualizing a hierarchical structure of simple values

All of them need to be wrapped inside JScrollPane to work correctly for large content

Tabs, Splits

JTabbedPane for splitting the content into tabs (label + icon)
JSplitPane for splitting exactly two components
JScrollPane for wrapping a component that can grow indefinitely

Rich Text

Many components support HTML for rich-text possibilities
The text needs to be prefixed with <html>
- Without the need for closing pair tag </html>
Then a whole lot of HTML tags can be used
- For adjusting font attributes
- For hypertext links
- Etc.