Graphical User Interfaces - Building Java Programs: A Back to Basics Approach - page 825

The program's output is a bit silly—it's just a tiny window:

In fact, there is another problem with the program: Closing the window doesn't
actually terminate the Java program. When you display a JFrame on the screen, by
default Java does not exit the program when the frame is closed. You can tell that the
program hasn't exited because a console window will remain on your screen (if
you're using certain Java editors) or because your editor does not show its usual mes-
sage that the program has terminated. If you want the program to exit when the win-
dow closes, you have to say so explicitly.
To create a more interesting frame, you'll have to modify some of the properties of
JFrame s. A property of a GUI component is a field or attribute it possesses internally
that you may wish to examine or change. A frame's properties control features like the
size of the window or the text that appears in the title bar. You can set or examine these
properties' values by calling methods on the frame.
Table 14.3 lists several useful JFrame properties. For example, to set the title text
of the frame in the SimpleFrame program to “A window frame”, you'd write the fol-
lowing line of code:

frame.setTitle("A window frame");

Table 14.3 Useful Properties That Are Specific to JFrames

Property Type Description Methods

default Close What should happen when the int getDefaultCloseOperation,

operation frame is closed; choices include:

setDefaultCloseOperation(int)

• JFrame.DO_NOTHING_ON_
CLOSE (don't do anything)
• JFrame.HIDE_ON_CLOSE
(hide the frame)
• JFrame.DISPOSE_ON_CLOSE
(hide and destroy the frame so
that it cannot be shown again)
• JFrame.EXIT_ON_CLOSE
(exit the program)

icon image The icon that appears in the

Image getIconImage,

title bar and Start menu or Dock setIconImage(Image)

layout An object that controls the

LayoutManager getLayout,

positions and sizes of the

setLayout(LayoutManager)

components inside this frame

resizable Whether or not the frame allows

boolean isResizable,

itself to be resized

setResizable(boolean)

title The text that appears in the

String getTitle, setTitle(String)

frame's title bar