Xoom Software Developer interview questions

It was a phone interview. As expected on time one of the engineers gave me call and started discussion. After usual questions like tell me about yourself and background they gave me a program of perfect number and asked for find bugs, improve code and java styles and code. Then folioing questions were asked OOPS principal - which principal you used to improve your design What is static keyword and where do you use. How to implement multiple inheritance without using Interface in Java Question builder pattern Other normal questions like how long you have been working in Java, Spring etc.