To test the Text Editor:
Set the classpath of the lib directory of J2SDK by executing the following command at the command prompt:
set classpath = %classpath%;d:\j2sdk1.4.0_02\lib;
Copy the Editor.java, ActionPerform.java, ColorClass.java, FontClass.java, PrintClass.java, and Help.java files to a folder on your computer. Compile the files using the following javac command:
To run the Text Editor, specify the following command at the command prompt:
Select the File->New command from the menu bar. A new text file is opened in the Text Editor, as shown in Figure 6-7:
Figure 6-7: The Untitled Text Editor Window
Write Hello, this is a sample file, in the currently untitled text file.
Select the File->Save As command from the menu bar to save the file. A Save As dialog box appears, as shown in Figure 6-8:
Figure 6-8: Save As Dialog Box
In the Save As dialog box, specify the file
Select the File->New command from the menu bar to clear the text area.
Select the File->Open command from the menu bar to open the
file, Test.txt. The
Figure 6-9: Open Dialog Box
Click the Open button of the Open dialog box that opens the Test.txt file from C:\CodeBook in the Text Editor, as shown in Figure 6-10:
Figure 6-10: Displaying the Test.txt File
Select the Format->Font command from the menu bar to open the
Font dialog box, as shown in Figure 6-4. Specify the font as
Figure 6-11: Displaying the Test.txt File with Selected Font
Select the Format->Color command from the menu bar to open
the Color dialog box, as shown in Figure 6-10. Specify the RGB
values in this dialog box and click OK. The
Figure 6-12: Displaying the Test.txt File with Selected Color
Select the Lock->Exclusive Lock command from the menu bar. This locks the Test.txt file.
Select the Start->Programs->Accessories->Notepad command to open a Windows notepad utility.
Select the File->Open command from the menu bar of the Notepad utility. Open the Text.txt file from the C:\CodeBook location.
Change the contents of the file and select the File->Save command from the menu bar. An error message appears because the file is locked, as shown in Figure 6-13:
Figure 6-13: Displaying Error Message
The New Input/Output (NIO) API provides the java.nio,
java.nio.channels, and java.nio.charset packages for buffer
management, socket handling, and data transfer. The java.nio
package contains the ByteBuffer and CharBuffer classes that you can
use to read and store the bytes and characters. To connect the
application to a network, you can use the SocketChannel class that
is available in the java.nio.channel package. The java.nio.charset
package provides two classes, Charset and CharsetDecoder. You can
use these classes to set the character sets and decode the bytes to
This chapter explains how to develop a Network Information application using the java.nio, java.nio.channels, and java.nio.charset packages.
The Network Information application displays a list of computers
connected in a network. Using this application, you can display the
echo time or the current system date and time of a specific
computer. For example, ABC Inc has corporate offices in three
NetCompFrame.java: Creates a
NetCompConnect.java: Implements the functions of the Network Information application. This file connects the application to the network using socket channels.
CompInfo.java: Provides information about the network computer.
CompInfoDialog.java: Creates a dialog box that displays the echo time and current system date and time of a computer.
Figure 7-1 shows the architecture of the Network Information application:
Figure 7-1: Architecture of the Network Information Application
In the Network Information application, the NetCompFrame.java file calls the NetCompConnect.java and CompInfoDialog.java files. The NetCompConnect.java file connects the application to the network at the specified port number and calls the CompInfo.java file to retrieve the computer information. The CompInfoDialog.java file displays the computer information by calling the CompInfo.java file.