Java Reference
In-Depth Information
Section 22.8
JTabbedPane
•A
JTabbedPane
(p. 936) arranges GUI components into layers, of which only one is visible at a
time. Users access each layer by clicking its tab.
Section 22.9
BoxLayout
Layout Manager
•
BoxLayout
)p. 939) arranges GUI components left-to-right or top-to-bottom in a container.
• Class
Box
represents a container with
BoxLayout
as its default layout manager and provides
stat-
ic
methods to create a
Box
with a horizontal or vertical
BoxLayout
.
Section 22.10
GridBagLayout
Layout Manager
•
GridBagLayout
(p. 942) is similar to
GridLayout
, but each component size can vary.
•A
GridBagConstraints
object (p. 943) specifies how a component is placed in a
GridBagLayout
.
Self-Review Exercises
22.1
Fill in the blanks in each of the following statements:
a) The class is used to create a menu object.
b) The method of class
JMenu
places a separator bar in a menu.
c)
JSlider
events are handled by the
method of interface
.
d)
The
GridBagConstraints
instance variable
is set to
CENTER
by default.
22.2
State whether each of the following is
true
or
false
. If
false
, explain why.
a)
When the programmer creates a
JFrame
, a minimum of one menu must be created and
added to the
JFrame
.
b)
The variable
fill
belongs to the
GridBagLayout
class.
c)
Drawing on a GUI component is performed with respect to the (0, 0) upper-left corner
coordinate of the component.
d)
The default layout for a
Box
is
BoxLayout
.
22.3
Find the error(s) in each of the following and explain how to correct the error(s).
a)
JMenubar b;
b)
mySlider = JSlider(
1000
,
222
,
100
,
450
);
c)
gbc.fill =
GridBagConstraints.NORTHWEST
;
// set fill
d)
// override to paint on a customized Swing component
public void
paintcomponent(Graphics g)
{
g.drawString(
"HELLO"
,
50
,
50
);
}
e)
// create a JFrame and display it
JFrame f =
new
JFrame(
"A Window"
);
f.setVisible(
true
);
Answers to Self-Review Exercises
22.1
a)
JMenu
. b)
addSeparator
. c)
stateChanged
,
ChangeListener
. d)
anchor
.
22.2
a)
False. A
JFrame
does not require any menus.
b)
False. The variable
fill
belongs to the
GridBagConstraints
class.
c)
True.
d)
True.
22.3
a)
JMenubar
should be
JMenuBar
.
