How to create a JAVA application WITHOUT the use of a Commercial IDE
Recently I decided I was bored and needed to learn something new. So I decide to try JAVA seeing as that was the Language that many others on this forum had chosen.
But unlike everyone else here. I wanted to learn from the ground up, and not rely on some fancy IDE.
Or I wanted to learn ‘Long Division’ before buying a calculator.
It took me hours of research, and consultations with both Norman and Thorsten. Before I was able to ferret out a series of steps the worked. So here is ONE approach. If anyone has alternative syntax or steps feel free to let me know.
NOTE : These steps are specific to macOS, but should be “mostly” the same for Window/Linux
Step 01
Decide on the NAME for you application [we will use ‘FOO’ here]
you should of course select a name that is appropriate for your project
Step 02
Create an empty directory structure with the name of your application [FOO]
Step 03
write your java source using your favorite Text Editor
[IMPORTANT… each file MUST use ‘.java’ as the extension]
store these files in the FOO directory
Note : the hows and whys of the actual Java programming language syntax can be found elsewhere
Step 04
execute TERMINAL
navigate to the FOO directory you created above
compile your Java Source using this command
javac -classpath . *.java
This tells java to compile ALL *.java files located in the current directory [-classpath .]
use javac --help if you want to see more compiler options
Step 05
in your favorite text editor create a file named ‘MANIFEST.MF’
Edit this file and insert the following lines
IMPORTANT! this file must contain no addtional whitespace, there are no spaces BEFORE the “:” and only ONE after it, and the file MUST end with a Linefeed
Main-Class: XXXXX
Replace XXXX with the class name from one of your .java files that is “main”, see example below
Step 06
create a JAR file from everything… a JAR is a Java ARchive
jar -cmvf MANIFEST.MF foo *.class
Step 07
Execute your new Java program using
java -jar foo
Example :
Create a Directory named “OldMac”
copy these 3 files
File #1 - name OldMacDriver.java
public class OldMacDriver {
public static void main( String[] args ) {
OldMacCow maudine = new OldMacCow();
OldMacCow pauline = new OldMacCow();
maudine.moo();
pauline.moo();
OldMacDuck ferdinand = new OldMacDuck();
ferdinand.quack();
}
}
File #2 - name OldMacCow.java
public class OldMacCow {
public void moo() {
System.out.println("Cow still says moo.");
}
}
File #3 - name OldMacDuck.java
public class OldMacDuck {
public void quack() {
System.out.println("Duck still says quack.");
}
}
here are our “steps”
Step 01 - name of our App is “OldMac”
Step 02 - we created our directory
Step 03 - we added 3 .java source code files
Step 04 - go to terminal, CD to “OldMac” and execute
javac -classpath . *.java
this will create a .class version of each .java file
Step 05 - create a file called 'MANIFEST.MF" with the contents
Manifest-Version: 1.0
Main-Class: OldMacDriver
NOTE : ‘OldMacDriver’ is the class named in our 1st Java file above
Step 06 - create a JAR file using
jar -cmvf MANIFEST.MF OldMac *.class
Step 07 - Run it
java -jar oldmac
Output should be
Cow still says moo.
Cow still says moo.
Duck still says quack.
Note… this is a SIMPLE example… and I’ll be honest , if there are issues, I may or may not be able to help… I myself have just started to learn all of this
But I hope this helps
