How do i start the program?

You use the shell script runApp.sh if you are a unix (linux, MacOSX) user or the batch file runApp.bat. Some times depending on the configuration of your system, you can double click on myBill.jar. If nothing of the above works, you can just type java -jar myBill.jar in a command prompt.

Why does it take so long to start

If you are using an old computer, it may take some time to start. I cannot do much about it, java is a bit slow at the load time. In more modern computers it does not take any time at all.

How do i insert decimal numbers?

You should type your decimal numbers in the format xxxx.xx (e.g 1234.15) If you use any other format (e.g 1.234,12) you will get an error.

How do i insert dates?

The date format is YYYY-MM-DD (e.g 2010-10-01 for first of October 2010).

Why is the date and number formatting so weird?

This is the format used in the internal database of the application

Why do you keep company data and invoice/bill data in separate tabs

I want to use one tab for all the data manipulation of each concept. If i was to use edit or delete operations of companies in the invoice/bill tab, things would be more confusing.

Why do i have to go back and forth when i want to insert a company and then an invoice

It is indeed a bit annoying at the beginning when the database does not hold any company data at all, that the user has to insert the company and then go to the invoice tab to insert the invoice However as the database grows and most of the companies you use frequently are in the database, then this happens rarely.