README.md

Collections

• HashMap and ConcurrentHashMap
• Generics, covariance, and contravariance
• LinkedHashMap and LinkedHashSet
• Remove ArrayList element inside foreach

Concurrency

• AbstractQueuedSynchronizer
• CyclicBarrier
• LinkedBlockingQueue
• ReentrantLock
• Synchronized, biased lock, and lightweight lock
• ThreadPoolExecutor
• Thread states
• ThreadLocal
• Volatile and singleton

JVM

• Classloader
• What happens when you create a new object
• GC
  • CMS
  • G1
• How to debug jvm memory issues
• Perm gen

Spring

• AOP
• How does Spring solve circular dependnecy?
• Spring bean life cycle? How are init-method and destory-method implemented?