HCI: Advanced Swing, Handling Texts

1
HCI Advanced Swing, Handling Texts

• Advanced Swing
• Handling texts
• Reading Swing tutorial

2
Look and Feel

• You can set the Look and Feel of a Swing
  program
• windows (PC)
• metal (original Java)
• motif (common on Unix)
• Define your own using GTK
• Affects appearance, not function

3
Look and feel examples
Metal (Java) (NetBeans default)
Windows
Motif
4
Setting Look and Feel

• Set in NetBeans
• Start-up parameter
• Set at run-time
• in main method before GUI instance form
• For platform (eg, Window on Windows PC)
• try UIManager.setLookAndFeel(UIManager
  .getSystemLook AndFeelClassName())
• catch (Exception e) System.out.println(e.toStri
  ng())

5
Look and Feel

• Swing mechanism criticised for not being very
  effective
• One reason Swing not widely used?
• SWT alternative to Swing
• IBM, Eclipse
• VEP GUI builder
• Claims to do a better job of adapting to the
  platforms look and feel

6
Text Components

• Powerful!
• Formatted text, colours, embedded graphics,
  clickable hyperlinks
• Input/output from HTML and RTF (word)
• some support for undo/redo
• Complex to use
• See Swing tutorial

7
Graphics

• Java2D package
• Paint tool for Java
• Draw lines, points, shapes, text
• arbitrary shape, size, colour
• Include images (eg, GIF files)
• Detect what user clicked mouse on
• also Java3D package
• Will discuss later in course

8
Sound

• AudioClip plays sounds from WAV, etc
• once, looping
• simple to use
• Java Media Framework (JMF)
• more powerful, more complex
• more control
• plays video as well as audio

9
Timer

• Ticks (triggers an action) at specified
  intervals
• delay (millisec)
• whether once-shot or repeats
• action
• Useful for animations
• 3 versions Java, Swing, NetBeans
• Under Beans palette in NB

10
Fancy widgets

• JFileChooser
• JColorChooser
• JToolBar
• JTable
• JTree
• JProgressBar

11
Swing in Java versions

• Coming in Java 5 (1.5)
• More look and feels (skin like?)
• Set default location for window
• Better integration with Windows for Unicode
• Incremental changes, not huge
• Swing is not focus of development efforts

12
Handling Text

• User enters information in GUI
• How can we get this information into our program?
• Programs produces information for user
• How can we display this on the GUI?

13
Typical Event Handler

• Read information from GUI widgets
• Convert to internal form (eg, int)
• Do computations
• Convert back to strings
• Display in GUI widgets

14
Read from GUI

• Each widget has method(s) for reading its value
• text fields getText() method
• list getSelectedValue(), getSelectedValues()
• checkbox isSelected()
• etc

15
Display in GUI

• Also methods for setting values
• text fields setText(String) method
• list setSelectedIndex(int), setSelectedValue(Obje
  ct)
• checkbox setSelected(boolean)
• etc

16
String lt-gt int, etc

• Converting text to/from integers, doubles, dates,
  etc.
• How can we read formatted data
• 21 March 2001, 2.35E-2
• How can we write formatted data?
• 2.35E-2
• 0.0235
• 0.02

17
Basic String-gtint, etc

• Integer.parseInt
• optional radix
• Double.parseDouble
• also Float.parseFloat
• Boolean.valueOf
• throw Exception if text isnt a legal int,
  double, etc

18
Basic int/etc -gt text

• String.valueOf
• int, double, float, boolean, etc
• no control over appearance
• also Integer.toString, etc

19
Example double

• Read in number from text box, double it, write it
  back to the text box
• String input textBox.getText()
• int value Integer.parseInt(input)
• value value2
• String output String.valueOf(value)
• textBox.setText(output)

20
Catch errors

• String input textBox.getText()
• try
• int value Integer.parseInt(input)
• value value2
• String output String.valueOf(value)
• textBox.setText(output)
• catch (Exception ex)
• JOptionPane.showMessageDialog(this,
  ex.toString())

21
Real numbers

• String input textBox.getText()
• try
• double value Double.parseDouble(input)
• value value2
• String output String.valueOf(value)
• textBox.setText(output)
• catch (Exception ex)
• JOptionPane.showMessageDialog(this,
  ex.toString())

22
Richer formatting java.text

• NumberFormat - formatting numbers
• DateFormat - formatting times/dates
• MessageFormat - formatting strings
• not discussed here, just concatenate
• Depend on Locale (location)
• 29 March 2002 (UK)
• March 29, 2002 (US)

23
NumberFormat

• For more complex formatting
• Create a formatter, use for input and output
• many types (currency, percent, etc)
• locale-specific
• parse method for input
• format method for output

24
Example (doubleGui)

• Import java.text.
• String text numberField.getText()
• NumberFormat nf NumberFormat.getInstance()
• // default formatter for UK locale
• double value nf.parse(text).doubleValue()
• value value2
• numberField.setText(nf.format(value))

25
Inputs and outputs

• Allowable inputs
• 1000
• 1,000
• 1000.0
• Output of double
• 2,000

26
Other formats

• NumberFormat.getCurrencyInstance()
• input 2000
• output 4000.00
• NumberFormat.getPercentInstance()
• make value a double
• input 20 becomes 0.2
• output 0.4 becomes 40

27
DecimalFormat

• Provides exact control of number format
• eg, can avoid scientific format (1.23E-02)
• Based on patterns
• nf new DecimalFormat(0.)
• one integer digit, up to 2 fractional digits
• 3
• 0.04
• 1.23
• see documentation for details

28
Example

• Import java.text.
• String text numberField.getText()
• DecimalFormat nf new DecimalFormat(0.)
• // default formatter for UK locale
• double value nf.parse(text).doubleValue()
• value value2
• numberField1.setText(nf.format(value))

29
JFormattedTextField

• Text field with associated formatter
• Constructor specified formatter
• getValue() gets value using formatter
• Combines getText() and parse()
• setValue shows value using formatter
• Combines format() and setText()
• Value shown updates when focus lost
• Hard to use from NB, wont discuss

30
Date, Time format

• DateFormatter - like NumberFormatter
• types date, time, datetime
• lengths
• Short 08/02/02
• Medium 08-Feb-02
• Long, Full 08 February 2002
• SimpleDateFormatter - specify format
• using pattern, like DecimalFormat

31
Example

• Import java.text., java.util.Date
• String text box.getText()
• DateFormat df DateFormat.getDateInstance(DateFor
  mat.SHORT)
• Date value df.parse(text)
• box.setText(df.format(value))

32
Parsing Strings

• Breaking a string up into values
• known as tokenisation
• Fred went home -gt Fred, went, home
• Java.util.StringTokenizer

33
Example

• StringTokenizer st new
• StringTokenizer("this is a test")
• while (st.hasMoreTokens())
• println(st.nextToken())
• this
• is
• a
• test

34
Parameters

• Delimeters characters that sep tokens
• typically space, comma, full stop,
• Flag are delimeters tokens

35
Other parsers

• Java.io.StreamTokeniser
• many more parameters, intended for input from
  file or terminal
• Java.util.regex
• regular expressions
• Lemmatisers
• children -gt childplural
• research systems

36
Summary

• Read string from GUI using getText, etc
• Convert string into int, double if required,
  using a formatter
• Do computations
• Convert int, double, etc into string using a
  formatter
• Display string on GUI using setText, etc