without trying to confuse me with million dollar words, can someone in plain english tell me why and what is an assertion and why we must or not use them
-enableassertions or -ea

An assertion is just a statement of something that should always be true. For example 1==1 ought always to be true, right? You mainly use assertions when you're developing or testing code. So, if you'd expect a variable to be equal to 5, you assert myVar==5; If it isn't equal to 5, the program will explode or the test will fail - letting you know that your expectation was wrong and the code was doing something different.

I hope that sort of answers your question.

--
Charlie Harvey's website - linux, perl, java, anarchism and punk rock: http://charlieharvey.org.uk

thank you, I felt as if I was missing something

Although I use them often in my code, I didn't know what they were called, thanks for the question and the answer :) .

"Only the strong survive."