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CS12420 - Lecture 02 Menus. Lynda Thomas ltt@aber.ac.uk. Menus are like Buttons. Use a Listener Classes involved are: JMenuBar JMenu JMenuItem Warning: you may use words slightly differently!. MenuBar. Menu. MenuItem. Look in menus directory for FirstMenuFrame.java. Alternatively.

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Cs12420 lecture 02 menus

CS12420 - Lecture 02Menus

Lynda Thomas

ltt@aber.ac.uk


Menus are like buttons
Menus are like Buttons

  • Use a Listener

  • Classes involved are:

    • JMenuBar

    • JMenu

    • JMenuItem

  • Warning: you may use words slightly differently!


Cs12420 lecture 02 menus

MenuBar

Menu

MenuItem



Alternatively
Alternatively

  • You could use a separate MenuListener class

  • See SecondMenuFrame.java and MenuListener.java

  • Let’s step through code with debugger and see animation of what is happening...


Cs12420 lecture 02 menus

1: new SecondMenuFrame()

JFrame

4: new

MenuListener(this)

MenuListener

SimpleFrame

smFrame

SecondMenuFrame

7: setPanelColor(Color.green)

3: new ColorPanel

JMenu

Colours

JMenu

Options

JMenuItem

Green

JMenuBar

JMenuItem

JMenuItem

JMenuItem

JMenuItem

2: new JMenu*

JPanel

ColorPanel

6: select green:

actionPerformed called

5: e.g. green.addActionListener(menuList)



Layout managers
Layout Managers

  • BorderLayout is default for JFrame

  • FlowLayout is default for JPanel

  • GridLayout:

    public TextPanel() {

    setLayout(new GridLayout(2,2,5,5));

    //2 rows, 2 cols, spaces

    add (new JLabel("Amount: "));

    inputField=new JTextField(8); add (inputField);

    add (new JLabel("Balance: "));

    balanceField=new JTextField(8); add (balanceField);

    }


Possible mistakes
Possible mistakes:

  • Misspelling javax.swing in import

  • Forgetting setVisible(true) (done for you in SimpleFrame)

  • Forgetting the JFrame.EXIT_ON_CLOSE

  • If buttons etc. don’t work:

    • Have you got something Listening to the button?

    • Is there an appropriate action in actionPerformed?

    • Try just printing ‘they hit button X’


More components
More components

Radio buttons and Combo boxes

ComboBoxDemo.java

and

RadioButtonDemo.java


In this lecture
In this lecture

  • We looked at menus

    In the next lecture we look at drawing