Oracle's OCAJP (1Z0-803) exam passed!

Last week I've passed Oracle Certified Associate, Java SE 7 Programmer(1Z0-803) exam with not a very shining score of 85%. So, I've decided to give some tips & tricks for readers of my blog on how to prepare and pass the exam.

First of all - my impressions about the exam. Exam is tough. The exam asks simple questions (lets say - basics) about Java, but you must know them. For example: Is there a difference between:

java.lang.ClassNotFoundException: javax.servlet.AsyncContext

I updated my project to Spring 4 and got error:

java.lang.ClassNotFoundException: javax.servlet.AsyncContext

After some googling I found the problem: AsyncContext was introduced into Servlet API 3.0, but I was using Servlet API 2.5. So, the solution is simple - add the following Maven dependency:

Could not find the required version of the Java(TM) 2 Runtime Environment

Today I wanted to install Java EE 7 SDK. I downloaded installer from Oracle's website and when I wanted to run it - I got an error, saying "Could not find the required version of the Java(TM) 2 Runtime Environment".
Ok, I know that I must have Java JRE to run installer of Java EE. But I have Java JRE... So... After some googling I found a solution - to run installation with option -j :

> java_ee_sdk-7-jdk7-windows-x64.exe -j "C:\Program Files\Java\jdk1.7

How to generate public/private keypair with RSA?

I'm developing several projects which use public/private key cryptography. So, the question is simple: how to generate public/private key pair?

As for me, I use OPENSSL to generate RSA key pair. It's simple:

openssl genrsa -out mykey.pem 2048

And public key can be generated like this:

openssl rsa -in mykey.pem -pubout >