Interview Q

Here is the Java interview questions with their justification on various topics

OOPS concept

• Constructor in Java
• Interface in Java
• Interface in Java 8
• Abstract classes and method in Java
• Method Overriding in Java
• Method Overloading in Java
• Various ways to create Object in Java – 4 ways

Java keywords

• this keyword in Java
• super keyword in Java
• final keyword in Java

Core Java

• Exception handling interview question
• Interview question on Java collection framework overview
• Java Collection Interview question and answers
• Generics interview question and answers
• Serialization interview question and answers

Advanced Java / JDBC

• JDBC

Difference between

• Interface v/s Abstract Classes
• Method v/s Constructor
• Default constructor v/s Parametrized constructor
• Static Initialization blocks v/s Instance Initialization blocks
• Method Overriding v/s Method Overloading
• ArrayList v/s LinkedList
• Arrays v/s ArrayList
• ArrayList v/s Vector
• Enumeration v/s Iterator v/s ListIterator interfaces
• Comparable v/s Comparator
• HashSet v/s LinkedHashSet
• List v/s Set
• HashMap v/s Hashtable
• HashMap v/s HashSet
• HashMap v/s LinkedHashMap v/s TreeMap
• HashMap vs LinkedHashMap
• HashSet v/s LinkedHashSet v/s TreeSet
• ConcurrentHashMap v/s HashMap
• ConcurrentHashMap v/s SynchronizedMap
• CopyOnWriteArrayList v/s ArrayList
• CopyOnWriteArrayList v/s SynchronizedList
• CopyOnWriteArraySet v/s HashSet
• CopyOnWriteArraySet v/s SynchronizedSet
• Error v/s Exception
• throw v/s throws in Java
• final v/s finally v/s finalize
• Checked Exception v/s Unchecked Exception
• Difference between ClassNotFoundException v/s NoClassDefFoundError
• Serializable v/s Externalizable
• REST v/s SOAP
• Local v/s Remote v/s Central Repositories in Apache Maven
• BeanFactory v/s ApplicationContext in Spring
• throws clause v/s try-catch-finally block

Interview programs

• Declaration, Definition, Initialization and Instantiation, Instance of class
• Why the execution order of Constructor and Initialization blocks is pre-defined?
• Interview program on String using toString() method
• Interview program on String using null
• Interview program on static method in Java
• Interview question on ModelAndView and DispatcherServlet in Spring MVC
• Java – Throw exception when second instance is created

Duplicate count programs

• Java 8 – Find employee count in each department ?
• Java 8 – Find duplicate count from Integer arrays ?

Design pattern

• Singleton design pattern – restricting all 4 ways of Object creation in Java
• Java Interview – How to create Thread-safe Singleton class ?
• How to construct an immutable class in Java

Spring framework

• Spring Boot – Interview question on server port configuration
• Spring MVC – Interview question on ModelAndView and DispatcherServlet

Upcoming articles

• String interview question
• Threads & Multi-Threading interview question
• File Handling interview question

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