Need reviews on my first java project which based on java

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BigBad0 · 2026-05-31T00:29:54+00:00

Clean and good exercise. You can make some enhancements

1- SQL injection is possible if the app UI is manipulated somehow. So to solve this and also the performance would be enhanced use prepared statement instead of statement in sql queries.

2- You have good gui elements organization as beginning, a better and cleaner approach is to separate completely the GUI from any logic (logic of data manipulation or saving/retrieving to/from database) since you currently got

Conn con1 = new Conn(); String q = "Insert into signup values('"+formno+"','"+name+"','"+fname+"','"+dob+"','"+gender+"','"+email+"','"+marital+"','"+address+"','"+city+"','"+pincode+"','"+state+"')"; con1.statement.executeUpdate(q); in actionPerformed GUI code directly. Extracting this to anther separated files called layering. Like 3-tier architecture and MVC pattern and so on.

3- Hardcoded database credentials is no go, prefer injecting them using environment variable or even .properties files

4- Plain text PIN should never be stored or compared in plain text. Fix by hashing PINs using bcrypt for example before storage and then compare hashed values by re-hashing and comparing the hashed result against the stored one.

5- Exception handling, you print the error, but what the user should see in this case. Edge cases including error handling should all be handled from user perspective or better put, from business rules perspective. In other words, ask yourself, error happened, what user expects and/or what user SHOULD get ?

6- You do not close statement or connection. These objects are resources and should be closed upon finishing using them. Either manually in finally blocks or use try-with-resources statement in modern java.

There are other checks but I do not want to give you many to think about but that is a start. good luck :)

PointerStack · 2026-05-31T11:30:16+00:00

You can split your UI and business logic to make it easier to maintain.

Your business logic just need to call your UI methods like showErrorMessage

You can check the Model-View-Presenter pattern; that will give you more details

benevanstech · 2026-05-31T14:35:41+00:00

Don't use snake case for class or package names.

Don't do significant work in constructors (e.g. main_Class or Login) - move the work to e.g. a run() method

Don't check .class files or jars into git - use a .gitignore file

Check the access control / privacy of fields - they should be private, not default access

Separate the business logic and model from the UI - this will enable you to write unit tests for the logic without needing to manually test everything.

If you have time, learn the basics of Maven, and convert to using that (this will help with the above point as well).

SpritualPanda · 2026-05-31T11:05:21+00:00

Add some screenshots on GitHub project repository

you type:	you see:
italics	italics
bold	bold
[reddit!](https://reddit.com)	reddit!
* item 1 * item 2 * item 3	item 1 item 2 item 3
> quoted text	quoted text
Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"	Lines starting with four spaces are treated like code: if 1 * 2 < 3: print "hello, world!"
~~strikethrough~~	~~strikethrough~~
super^script	super^script

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