Domanda di colloquio di Tech Mahindra

Java ———— 1. what is Z garbage collector 2.hashMap vs Linked hashMap vs TreeMap 3.can we create constructor in abstract class 4. What is Predicate and what is it’s return type 5. What are Predicate uses and methods 6. Serialisation vs externalisation 7. String buffer and string builder difference 8. can we have constructor in abstract class. If yes then why we need them. 9. How can we stop cloning singleton class. 10. can we use string builder and string buffer as key in Hashmap Spring boot & Microservices ——————— 1. What is saga pattern 2. What is multi part 3. How to implement circuit breaker 4. Spring AOP. 5. one annotations he asked which I don't remember