* Make your fundamental java knowledge strong
Firstly go through all the core java interview questions like
1. What is OOP concept?
2. What is abstraction, encapsulation, inheritance, polymorphism principle? Difference among all these four principles.
3. What are some basic features of Core java language?
4. Why Java is preferred over other language?
5. What is the basic application of java language?
* Practice core java programming by running basic java program
Install basic java software on your desktop/laptop and practice some basic program by proper running & execution. During java interview questions round, you would be surely asked to recognize the error present in the program given or written by you. If you do not have sufficient practice on java programming, then you would find it very difficult to find the minute error hidden in the many steps of the program. Many a times even a small semicolon, colon, bracket changes the complete execution of program. So practice the program on computer to excel into java interview questions.
* Use online & offline resources available for comprehensive knowledge
There are many books & questions series are available on Core java interview questions in both online as well as offline format. If you surf web regularly then you can subscribe to practice test series on basic java. Some of these practice tests are completely free while for others there is a nominal fee marked to the material so decide according to your need & prepare well interview questions on basic java. Beside if you are looking for hard copy version on Core java interview questions,then go through any book store & you will find numerous books on core java. But before buying look for the language & content as well as program illustrations. If you are not able to understand the content then it is futile to spend your money on that book. So choose the material wisely and prepare well for Core java interview questions.