Java

Main

• What is the difference between JDK, JRE and JVM?
• Do objects get passed by reference or value?
• Describe method signature
• What is the difference between overriding and overloading?
• What do you know about access modifiers?
• Can a constructor be inherited?
• Can a static method be overridden?
• What is enum?
• What is casting?
• What methods of Object class do you know?
• What do you know about anonymous classes?
• What is the difference between final, finally and finalize?
• What is the difference between int and Integer?
• What is the difference between inner classes and static nested classes?
• What do you know about try-catch-finally?
• Describe exception hierarchy
• Describe java memory model
• What is Java's Garbage Collection?
• What references types do you know?
• What is lambda expressions?
• What do you know about String pool?
• What is the difference between String, StringBuilder and StringBuffer?
• What is immutable object?
• What does transient keyword mean?
• What do you know about record?
• What do you know about generics?
• What do you know about wildcard?
• What is memory leak?

Collections

• What is the difference between Array and ArrayList?
• What are the basic interfaces of Java Collections Framework?
• Describe Queue interface from java collection
• Describe Deque interface from java collection
• What do you know about Iterator interface?

List

• Describe List interface
• What do you know about ArrayList?
• What do you know about LinkedList?
• What is the difference between ArrayList and LinkedList?
• What do you know about Stack?
• What do you know about Vector?

Map

• Describe Map interface
• Describe how HashMap works
• What do you know about TreeMap?
• What do you know about ConcurrentHashMap?
• What do you know about Hashtable?
• What is the difference between Hashtable vs ConcurrentHashMap?
• What do you know about EnumMap?
• What do you know about LinkedHashMap?

Set

• Describe Set interface
• What do you know about HashSet?
• What do you know about TreeSet?
• What is the difference between HashSet and TreeSet?
• What do you know about EnumSet?
• What do you know about LinkedHashSet?

Interfaces

• What is interface?
• What do you know about default method in interface?
• What is the difference between Abstract class and Interface?
• What do you know about Comparable interface?
• What do you know about Comparator interface?
• What is the difference between Comparable and Comparator interface?
• What do you know about Serializable interface?
• What is the difference between Stream and Iterator?
• What do you know about Clonable interface?
• What do you know about Executor interface?
• What do you know about Stream interface?

Multithreading

• What does the synchronized keyword mean?
• What does the volatile keyword mean?
• What is object monitor?
• What is semaphore?
• What is the difference between Semaphore and Monitor
• What do you know about double check pattern singleton?