I’ve never used a Java IDE; maybe I’ll try a few and write future posts about them. For now, my readers know that I use the command line.<\/p>\n
Let’s imagine you’ve written a standalone Java class such as To succeed, the file needs to be saved with the .java<\/span> file extension. Let’s imagine it’s saved P0.java<\/span> in the folder java_demos<\/span>. To compile it, you’d open the terminal, then enter that directory. Next, you’d key in<\/p>\n javac P0.java<\/span><\/p>\n If you get error messages, you’ll need to do some proofing. If the program compiles fine, you likely won’t get a message at all; rather, you’ll just see the command prompt appear on the next line.<\/p>\n Running the program can depend on your operating system.<\/p>\n From the Linux terminal, you can run the program thus:<\/p>\n java P0<\/span><\/p>\n However, from the Windows terminal, you might need to key in<\/p>\n java -cp . P0<\/span><\/p>\n In the case of yesterday’s post<\/a>, there is a class that uses another. In that case, the compile command should indicate both files (the one containing the main() <\/span> method, listed first):<\/p>\n javac MessagerDriver.java Messager.java<\/span><\/p>\n However, after a successful compile, the program can be run by calling only the first file:<\/p>\n (Linux)<\/p>\n java MessagerDriver<\/span><\/p>\n (Windows)<\/p>\n java -cp . MessagerDriver<\/span><\/p>\n Programs rarely compile and run the first try; usually, corrections need to be made because of missing parentheses, semicolons, or what have you. The compiler tries to tell what’s wrong, but in my experience, a missing bracket can lead to ten error messages as it tries to make sense of the code without it. Very often, one or two simple problems are all that’s wrong.<\/p>\n Good luck with your coding. I have so much to follow up from this post:)<\/p>\n Source:<\/p>\n Niemeyer, Patrick and Jonathan Knudsen. Learning Java<\/u>. Sebastopol, CA: O’Reilly Media, Inc, 2005.<\/p>\n
\n
\nclass P0{
\npublic static void main(String[] args){
\nSystem.out.println(“Congratulations from Java!”);
\n}
\n}<\/p>\n