There is no set pattern for the written test as such. The number of questions and the duration of the exam can be different for different areas. The test is conducted in online mode, which may or may not be subject to negative marking.
But what is certain is that the online Witten test will contain questions on following topics: · Computer Science Knowledge · Data Structures · OS Concepts · Verbal Ability · Reasoning · General English
You might get 30 questions in Technical section, 25 questions in English language section and 35 questions for reasoning. The duration of the exam can be expected to be of 90 minutes.
There are many certifications in Java. It is like a track one after another you have to do. The first one is OCAJP. This is the basic certification in Java even people who have no experience also will be able to prepare and pass the exam.
Here I am providing few links that talks about the preparation :
How to prepare for OCAJP exam? Where can I get the mock exams for OCAJP 7? Which book is good for preparing OCAJP SE8?
Next certification is OCPJP exams which is little tougher than tthe OCAJP exam. But, at this time you focus on only OCAJP Exam.
See regarding the logical part you need to practice as many questions as you can to get a good hand on them.Get thorough with the quants of 10th class and keep giving mock tests.Read different books and maintain good command on vocabulary.