SE1020

1
Creating Graphical User Interfaces
2
Placing GUI components on a JFrame

• There are two ways to put GUI components on the
  content pane of a JFrame
• Absolute positioning
• You explicitly specify the position and size of
  GUI objects within the content pane
• btnQuit.setBounds( 10, 125, 80, 30 )
• Use a Layout Manager
• A class that controls automatic placement of
  components

3
Layout Managers automatically determine how the
GUI components appear within the container

• Many different layout managers exist some are
• FlowLayout
• BorderLayout
• GridLayout
• To use, set the layout manager of a JFrames
  Container to the type of layout manager you want
  to use
• FlowLayout fl new FlowLayout(FlowLayout.CENTER)
  contentPane.setLayout(fl)

4
Using FlowLayout

• In using this layout, GUI components are placed
  in left-to-right order.
• When the component does not fit on the same line,
  left-to-right placement continues on the next
  line.
• As a default, components on each line are
  centered.

5
FlowLayout behavior when the frame containing the
components is resized
6
BorderLayout

• This layout manager divides the container into
  five regions center, north, south, east, and
  west.
• Not all regions have to be occupied.

7
BorderLayout resizing

• The north and south regions expand or shrink in
  width only
• The east and west regions expand or shrink in
  height only
• The center region expands or shrinks on both
  height and width.

8
GridLayout

• Places GUI components on equal-size N by M grids.
  
• Components are placed in top-to-bottom,
  left-to-right order.
• Number of rows and columns remains the same after
  the frame is resized, but the width and height of
  each region will change.

9
GridLayout resizing
10
Complex layouts

• For sophisticated GUIs, it can be difficult to
  use a single layout manager to get the look you
  are after.
• Another approach is to use panels
• Multiple panels can be placed in a content pane
• The class that implements a panel is JPanel

Panel 1
Panel 3
Panel 3
11
Using Panels

• Panels can be placed on a JFrame
• using absolute positioning
• using a layout manager
• Each panel can employ its own layout manager
• or not
• UI components are added to the panels, rather
  than the JFrame
• But you can still add components to the JFrame as
  well

BorderLayoutpanel
Absolutepositioningpanel
Flow Layout panel
12
Nested Layouts

• A panel can be placed inside another panel
• This is called nesting panels
• Nesting can be done to any level

Here, the East region of the outer panel contains
a border layout
13
Another nested panel example
Here, the Center region of the outer panel
contains a border layout
14
North
Center
South
15
North
Center
South