Core Java(TM) 2, Volume I--Fundamentals (7th Edition) (Core Series) (Core Series)

An integrated development environment accords many comforts but also insinuates some drawbacks. In particular, for simple programs that are not distributed over multiple source files, an environment with its long startup time and many bells and whistles can seem like overkill. Fortunately, many text editors can launch the Java compiler, launch Java programs, and capture error messages and program output. In this section, we look at Emacs as a typical example.

NOTE

Emacs is a splendid text editor that is freely available for UNIX, Linux, Windows, and Mac OS X. However, many Windows programmers find the learning curve rather steep. For those programmers, we can recommend TextPad. Unlike Emacs, TextPad conforms to standard Windows conventions. TextPad is available at http://www.textpad.com. Note that TextPad is shareware. You are expected to pay for it if you use it beyond a trial period. (We have no relationship with the vendor, except as satisfied users of the program.)

Another popular choice is JEdit, a very nice editor written in Java, freely available from http://jedit.org. Whether you use Emacs, TextPad, JEdit, or another editor, the concepts are the same. When you are done editing the source code, you invoke a command to compile the code. The editor launches the compiler and captures the error messages. You fix the errors, compile again, and invoke another command to run your program.

Figure 2-7 shows the Emacs editor compiling a Java program. (Choose JDE -> Compile from the menu to run the compiler.)

The error messages show up in the lower half of the window. When you move the cursor on an error message and press the ENTER key, the cursor moves to the corresponding source line.

Once all errors are fixed, you can run the program by choosing JDE -> Run App from the menu. The output shows up inside an editor window (see Figure 2-8).