CS110- Lecture 12 Mar 23, 2005

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CS110- Lecture 12Mar 23, 2005

• Agenda
• Questions on Project 2?
• Class dependencies
• Components and Containers

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Class dependencies

• The classes in a software system have various
  types of relationships to each other.
• We have seen many examples of dependency
  relationship in which one class uses another i.e.
  one class relies on another in some sense.
• Often the methods of one class invokes the
  methods of another class.
• Example
• ChaosGame is dependent on Die class
• MTSO class is dependent on Tower class
• Tower class is dependent on Location class

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Class Dependencies

• Sometimes a class depends on itself i.e. an
  object of one class interacts with another object
  of the same class.
• Example
• Location class is dependent on itself because
  distance method needs another Location object.
  Header of distance method is
• public double distance(Location other)

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Class dependencies

• Lets write a class ComplexNumber.
• Instance data
• Real part
• Imaginary part
• Methods
• sum(ComplexNumber other)
• prod(ComplexNumber other)
• neg()
• Various Setters and Getters

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Components and Containers (Section 3.9)

• We have used java capabilities to draw shapes
  using the Graphics and Color classes from
  standard library.
• We wrote applets to draw shapes.
• But we can also write applications (stand alone
  programs) with graphical components.
• We need main method to run such applications.

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Components and Containers

• A GUI component is an object that represents a
  screen element that is used to display
  information or allow the user to interact with
  the program in a certain way.
• GUI components include labels, buttons, text
  fields, radio buttons, check boxes and so on.

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Components and Containers

• GUI components and other GUI related classes are
  primarily in two packages
• AWT Abstract windowing toolkit (old)
• Components- Button, Label etc.
• Other Classes Color etc.
• Swing (New)
• Components- JButton, JLabel etc.
• Other classes Timer etc.
• We will still use some classes of AWT such as
  Color.
• But for components we will prefer using Swing
  Components.

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Components and Containers

• A Container is a special type of Component that
  is used to hold and organize other components.
• AWT
• Containers Frame, Panel etc.
• Swing
• Containers JFrame, JPanel etc.

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Frames

• Frame is a container that is used to display GUI
  based Java applications.
• Frame is displayed as a separate window with its
  own title bar.
• In can be resized, moved, maximized and
  minimized.
• In swing Frame is defined by the JFrame class.

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Panels

• Panel is also a container. However it cannot be
  displayed at its own. A panel must be added to
  another container for it to be displayed.
• Its primary role is to help organize the other
  components in a GUI.
• In swing panel is defined by JPanel class.

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Some Fundamental GUI components

• Label
• Displays a line of text.
• In swing label is defined by JLabel class.
• Button
• Allows user to click at them and we can associate
  an action when button is clicked
• In swing button is defined by JButton class

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Frames and Panels

• Lets write a class that gives us the following
  output.

Swing
Welcome to world of Swing Swing is Fun
OK
EXIT