Naming Convention of Files in Java

When I learn programming language like C or Python, I like to code multiple programs and execute them.  That is how I learn the programming language.  Usually I save all those programs in the same folder like "Demo" or "Learning" and name files starting with numbers like 01_HelloWorld.py, 02_IfStatements.py, 03_Loops.py, etc.,  This makes it easier for me to revisit and relearn or refresh the topics I've learnt.

However, in Java, i'm unable to save files starting with numbers because its not the accepted naming convention(class name can't begin with numbers) and also, it looks like I have to start separate projects for each topics like 'Print', 'IfKeyWords', 'Loops' etc which is like an obstacle for me because when I want to revist / refresh later, i want the order/sequence to be clear.  Any idea/advise/suggestions on how to overcome this?

Welcome to the Ranch, Sivakumar!

Actually, a LOT of programming languages -- and some operating systems -- don't like source filenames to begin with a non-alphabetic character. I doubt I've ever named anything other than data starting with a number.

For single-file programs, you could always suffix the filename with a sequence number. That will affect the name of the class, but for training purposes, who really cares if you name a file and class "TestPrint01.java"? Just remember that by Java convention, the first character in a class/file name must always be an upper-case letter!

For programs made from more than one source file, it's definitely better to make a separate directory for each set of files. Also, once things get really complicated, you'll find it useful to employ a build tool such as Maven.

Welcome to the Ranch (again)

Put those topics into different directories and use your file explorer program to display them in date order.

Campbell Ritchie wrote:Welcome to the Ranch (again)

Put those topics into different directories and use your file explorer program to display them in date order.

Unfortunately, that only works if you never come back and edit them later.

In Unix-like OS's, you can get the create date, but even there it's not the "normal" date used for date-order listing.

1. You can name a Java source file with a name that starts with a number. You just can't define a class by that name. The following works fine:
//in file 01_Test.java class Test{ public static void main(String[] args){   System.out.println("hello"); } }
You can compile the above file using "javac 01_Test.java" and run it using "java Test" commands.

2. If you don't want to have a non-public class, (making it public or not doesn't really matter if all you want to do is create test programs), you may name your files starting with a common prefix such as Test01.java, Test02.java and so on.

3. You don't have to create separate projects or folders. You can keep all your java source files in a single folder if you find that comfortable. If you are not trying out the package statement, you may keep all the class files in the same folder as well. It is only when you try out the package and import statements that you have to worry about the directory structure of the class files. The compiler or the JVM do not care about where the java source files reside. But generally, people organize them in the same directory structure as their package names.

Tim Holloway wrote:

Campbell Ritchie wrote:Welcome to the Ranch (again)

Put those topics into different directories and use your file explorer program to display them in date order.

Unfortunately, that only works if you never come back and edit them later.

In Unix-like OS's, you can get the create date, but even there it's not the "normal" date used for date-order listing.

Windows has Create Date and Modified Date columns too in the File Explorer.

Paul Anilprem wrote:1. You can name a Java source file with a name that starts with a number. You just can't define a class by that name. The following works fine:
//in file 01_Test.java class Test{ public static void main(String[] args){   System.out.println("hello"); } }
You can compile the above file using "javac 01_Test.java" and run it using "java Test" commands.

2. If you don't want to have a non-public class, (making it public or not doesn't really matter if all you want to do is create test programs), you may name your files starting with a common prefix such as Test01.java, Test02.java and so on.

3. You don't have to create separate projects or folders. You can keep all your java source files in a single folder if you find that comfortable. If you are not trying out the package statement, you may keep all the class files in the same folder as well. It is only when you try out the package and import statements that you have to worry about the directory structure of the class files. The compiler or the JVM do not care about where the java source files reside. But generally, people organize them in the same directory structure as their package names.

I want to thank each and every one of you for making me feel welcome and most importantly, taking your time to guide other newbies like me.  Thank you so much.  This solution worked like a charm.  Now, from the IntelliJ IDEA IDE, I go to New->File-> and give name like 01_Test.java.  Create a non-public class 'Test' and it got compiled & worked perfectly.  Now that I've overcome my major obstacle, i'll start coding regularly and learn as much as I can.  Can't thank you guys enough, you are all amazing!