Java,spring boot & Micro services

What is Invasive & Non Invasive ? what is POJO ? what is POJI ? what is Java Bean Class ? What is Bean class/Component class ? what is Spring Bean class ?

Synechron for UBS 1. What is OOPS principles ? What's is abstractions ? If interfaces in java 8 is similar to abstract class then why it is required ? 2. Composition and Aggregation 3.what is indexing in SQL ? types of index ? 4.what is difference between concurrentHashMap and hashMap ? What is LINKEDHASHMAP ? 4. Return in try and return in finally what value shoud return ? What happened if exception in finally ? 5. Design patterns in java ? What is singleton design pattern ? Where singleton pattern used ? 6. How to create custom exception ? 7.What is the difference between ClassNotFoundException and NoClassDefFoundError? 8. Difference between synchronised and lock 9. What is difference between notify ()and notifyall() ? If notifyall() then why required notify() ? 10. What is read write lock in java ?. 11. What is Retrancelock() ? 12 what I producer and consumer model ? What is blocking queue 13. What is countdownlatch ? What is cycallibarrier ? 14. What is java 7 features ? 15. What is SOLID principles