Day 14 A little more GUI

1
Day 14 A little more GUI

• Today well take a few minutes to say more about
• Text fields
• Checkboxes
• Radio Buttons

2
Recall

• Recall the MenuExample.java program from
  yesterday.
• It used a dialog box to read in text, a submenu
  of radio buttons to determine the font name, and
  a submenu of checkboxes to determine the font
  style.

3
An alternative

• Today well look at how to read in a string from
  a text field
• Also, well use JCheckBox instead of
  JCheckBoxMenuItem
• and JRadioButton instead of JRadioButtonMenuItem.
• Our program will display the check boxes and
  radio buttons directly on the screen rather than
  hiding them under a menu

4
Download TextFieldExample.java
5
JTextField

• Weve created JTextFields before, but we have not
  given them action listeners. This can be done as
  followsprivate JTextField jtfNamejtfName
  new JTextField(12)
• jtfName.addActionListener(this)
• controlPanel.add(jtfName)

6
JTextField

• An ActionEvent will be sent to the listener
  whenever focus is on the text field and the enter
  key is hit. We handle this event in our
  actionPerformed methodpublic void
  actionPerformed(ActionEvent e)
• if (e.getSource() jtfName)
• userName jtfName.getText()
• panel.repaint()

7
JCheckBox

• A JCheckBox is used like a JCheckBoxMenuItem.
• The main difference is that it extends JComponent
  rather than JMenuItem, so it is intended for use
  outside of menus.JPanel checkBoxPanel new
  JPanel()
• checkBoxPanel.setLayout(new FlowLayout())jcbBol
  d new JCheckBox("Bold")
• jcbBold.setMnemonic('B')checkBoxPanel.add(jcbBo
  ld)jcbBold.addActionListener(this)

8
JCheckBox

• As with a JCheckBoxMenuItem, the action listener
  will be notified when the JCheckBox is selected
  or deselectedpublic void actionPerformed(Action
  Event e)
• if (e.getSource() jcbBold)
• boldFont jcbBold.isSelected()
• panel.repaint()

9
JRadioButton

• JRadioButton is likewise very similar to
  JRadioButtonMenuItem.
• Again, the main difference is that you use
  JRadioButtons outside of menus.

10
JRadioButton

• JPanel radioBoxPanel new JPanel()
• radioBoxPanel.setLayout(new FlowLayout())
• jrbFontCourierNew new JRadioButton("Courier
  New")
• jrbFontCourierNew.setMnemonic('C')
• jrbFontDialog new JRadioButton(Dialog")jrbFo
  ntDialog.setMnemonic('D')
• jrbFontTimesNewRoman
• jrbFontVivaldi

11
JRadioButton

• This code adds the four radio buttons to a panel.
  It also draws a border around the
  panelradioBoxPanel.add(jrbFontCourierNew)
• radioBoxPanel.add(jrbFontDialog)
• radioBoxPanel.add(jrbFontTimesNewRoman)
• radioBoxPanel.add(jrbFontVivaldi)
• radioBoxPanel.setBorder(
• BorderFactory.createLineBorder(Color.BLACK))

12
JRadioButton

• As always, we need to add action
  listenersjrbFontCourierNew.addActionListener(th
  is)
• jrbFontDialog.addActionListener(this)
• jrbFontTimesNewRoman.addActionListener(this)
• jrbFontVivaldi.addActionListener(this)

13
JRadioButton

• The extra step that we need to perform for radio
  buttons is to put them in a group.ButtonGroup
  btg new ButtonGroup()
• btg.add(jrbFontCourierNew)
• btg.add(jrbFontDialog)
• btg.add(jrbFontTimesNewRoman)
• btg.add(jrbFontVivaldi)
• jrbFontDialog.setSelected(true)

14
JRadioButton

• The action listener code can be written as
  usualpublic void actionPerformed(ActionEvent
  e)
• if (source jrbFontCourierNew
  jrbFontCourierNew.isSelected())
• fontName "Courier New" else if
• panel.repaint()