Java Reference
In-Depth Information
•
KeyEvent
method
getKeyModifiersText
(p. 528) returns a string containing the pressed modifi-
er keys.
Section 12.18 Introduction to Layout Managers
• Layout managers (p. 528) arrange GUI components in a container for presentation purposes.
• All layout managers implement the interface
LayoutManager
(p. 528) of package
java.awt
.
•
Container
method
setLayout
specifies the layout of a container.
•
FlowLayout
places components left to right in the order in which they're added to the container.
When the container's edge is reached, components continue to display on the next line.
FlowLayout
allows GUI components to be left aligned, centered (the default) and right aligned.
•
FlowLayout
method
setAlignment
(p. 532) changes the alignment for a
FlowLayout
.
•
BorderLayout
(p. 532) the default for a
JFrame
) arranges components into five regions:
NORTH
,
SOUTH
,
EAST
,
WEST
and
CENTER
.
NORTH
corresponds to the top of the container.
•A
BorderLayout
limits a
Container
to containing at most five components—one in each region.
•
GridLayout
(p. 536) divides a container into a grid of rows and columns.
•
Container
method
validate
(p. 537) recomputes a container's layout based on the current lay-
out manager for the
Container
and the current set of displayed GUI components.
Section 12.19 Using Panels to Manage More Complex Layouts
• Complex GUIs often consist of multiple panels with different layouts. Every
JPanel
may have
components, including other panels, attached to it with
Container
method
add
.
Section 12.20
JTextArea
•A
JTextArea
(p. 539)—a subclass of
JTextComponent
—may contain multiple lines of text.
• Class
Box
(p. 540) is a subclass of
Container
that uses a
BoxLayout
layout manager (p. 541) to
arrange the GUI components either horizontally or vertically.
•
Box
static
method
createHorizontalBox
(p. 541) creates a
Box
that arranges components from
left to right in the order that they're attached.
•Method
getSelectedText
(p. 541) returns the selected text from a
JTextArea
.
• You can set the horizontal and vertical scrollbar policies (p. 542) of a
JScrollPane
when it's con-
structed.
JScrollPane
methods
setHorizontalScrollBarPolicy
(p. 542) and
setVertical-
ScrollBarPolicy
(p. 542) can be used to change the scrollbar policies at any time.
Self-Review Exercises
12.1
Fill in the blanks in each of the following statements:
a)
Method is called when the mouse is moved with no buttons pressed and an
event listener is registered to handle the event.
b)
Text that cannot be modified by the user is called
text.
c)
A(n)
arranges GUI components in a
Container
.
d)
The
add
method for attaching GUI components is a method of class
.
e)
GUI is an acronym for
.
f)
Method
is used to specify the layout manager for a container.
g)
A
mouseDragged
method call is preceded by a(n)
method call and followed by
a(n)
method call.
h)
Class
contains methods that display message dialogs and input dialogs.
i)
An input dialog capable of receiving input from the user is displayed with method
of class
.
