Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

174
175 // Display the status of the save file operation in jlblStatus
176 jlblStatus.setText(file.getName() + " Saved ");
177 }
178 catch (IOException ex) {
179 jlblStatus.setText("Error saving " + file.getName());
180 }
181 }
182 }
The program creates the File and Edit menus (lines 34-45). The
File menu contains the menu commands Open for loading a file,
Save for saving a file, Clear for clearing the text editor, and
Exit for terminating the program. The Edit menu contains the menu
commands Foreground Color and Background Color for setting
foreground color and background color in the text. The Open and
Save menu commands can also be accessed from the toolbar, which
is created in lines 56-58. The status of executing Open and Save
is displayed in the status label, which is created in line 24.
jFileChooser1, an instance of JFileChooser, is created for
displaying the file dialog box to open and save files (lines 27-
28). new File(".") is used to set the current directory to the
directory where the class is stored.
The open method is invoked when the user clicks the Open menu
command or the Open toolbar button (lines 62, 108). The
showOpenDialog method (line 125) displays an Open dialog box, as
shown in Figure 38.20. Upon receiving the selected file, the
method open(file) (line 127) is invoked to load the file to the
text area using a BufferedInputStream wrapped on a
FileInputStream.
The save method is invoked when the user clicks the Save menu
command or the Save toolbar button (lines 68, 114). The
showSaveDialog method (line 151) displays a Save dialog box. Upon
receiving the selected file, the method save(file) (line 153) is
invoked to save the contents from the text area to the file,
using a BufferedOutputStream wrapped on a FileOutputStream.
The color dialog is displayed using the static method showDialog
(lines 87, 98) of JColorChooser. Thus you don't need to create an
instance of JFileChooser. The showDialog method returns the
selected color if the OK button is clicked after a color is
selected.
Chapter Summary
1. Menus make selection easier and are widely used in window
applications. Java provides five classes that implement
menus: JMenuBar, JMenu, JMenuItem, JCheckBoxMenuItem, and
JRadioButtonMenuItem. These classes are subclasses of
AbstractButton. They are very similar to buttons.
2. JMenuBar is a top-level menu component used to hold menus.
A menu consists of menu items that the user can select (or
toggle on or off). A menu item can be an instance of
JMenuItem, JCheckBoxMenuItem, or JRadioButtonMenuItem. Menu
items can be associated with icons, keyboard mnemonics, and
keyboard accelerators. Menu items can be separated using
separators.
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