Introduction to Java Applications; Input/Output and Operators - Java: How to Program Early Objects - page 41

Executing the Welcome1 Application
The following instructions assume that the topic's examples are located in C:\examples
on Windows or in your user account's Documents/examples folder on Linux/OS X. To
execute this program in a command window, change to the directory containing
Welcome1.java — C:\examples\ch02\fig02_01 on Microsoft Windows or ~/Documents/
examples/ch02/fig02_01 on Linux/OS X. Next, type
java Welcome1
and press Enter . This command launches the JVM, which loads the Welcome1.class file.
The command omits the .class file-name extension; otherwise, the JVM will not execute
the program. The JVM calls class Welcome1 's main method. Next, the statement at line 9
of main displays "Welcome to Java Programming!" . Figure 2.2 shows the program execut-
ing in a Microsoft Windows Command Prompt window. [ Note: Many environments show
command windows with black backgrounds and white text. We adjusted these settings to
make our screen captures more readable.]
Error-Prevention Tip 2.4
When attempting to run a Java program, if you receive a message such as “ Exception in
thread "main" java.lang.NoClassDefFoundError: Welcome1 ,” your CLASSPATH envi-
ronment variable has not been set properly. Please carefully review the installation in-
structions in the Before You Begin section of this topic. On some systems, you may need to
reboot your computer or open a new command window after configuring the CLASSPATH .
You type this
command to execute
the application
The program outputs to the screen
Welcome to Java Programming!
Fig. 2.2 | Executing Welcome1 from the Command Prompt .
2.3 Modifying Your First Java Program
In this section, we modify the example in Fig. 2.1 to print text on one line by using mul-
tiple statements and to print text on several lines by using a single statement.
Displaying a Single Line of Text with Multiple Statements
Welcome to Java Programming! can be displayed several ways. Class Welcome2 , shown in
Fig. 2.3, uses two statements (lines 9-10) to produce the output shown in Fig. 2.1. [ Note:
From this point forward, we highlight with a yellow background the new and key features
in each code listing, as we've done for lines 9-10.]
The program is similar to Fig. 2.1, so we discuss only the changes here. Line 2
// Printing a line of text with multiple statements.