Principal Financial Group Java Developer Cloud interview questions

1. Introduce yourself, tech stack etc. 2. Abstract class vs Interface 3. Thread class vs runnable 4. Internal working of HashMap. 5. Few Questions on AWS. 6. Will Hashmap print null key with some value? 7. Difference between ArrayList and vectors 8. Synchronized method and block 9. Few questions about multithreading 10. Few questions on Springboot annotations.