Technical Musings !!

I am listing below the checklist of concepts and keywords in java which are most frequently asked in interview. Please excuse me for presenting it in a random order.

Following are the topics/keywords/concepts which require a crisp knowledge and understanding. These are basisc only.

• JVM – About JVM, JIT compiler, Bytecode, Classloader
• Garbage Colection – Conditions when JVM invokes garbage collection, System.gc()
• Static and Instance initializer block
• Datatypes – character especially
• enum – where to declare, defining constructor, methods and variables in enum
• OOP concepts – inheritance, polymorphism, aggregation vs Composition, abstraction
• Multiple Inheritance in java
• Difference/Similarities between interface and abstract class
• Software Engineering Concepts – Coupling and Cohesion
• String, StringBuffer and StringBuilder
• Exception Handling – Checked vs Unchecked Exceptions, Assertion, Error, Exception Hierarchy, throw vs throws
• final, finally and finalize
• Method Overriding (Rules for the same)
• Method Overloading – Covariant Return (Java5)
• Autoboxing
• Array – Declaring an anonymous and multidimensional array
• Keywords like super and this
• The Object classs – equals and hashcode methods
• Access Specifiers – default, public , protected and private
• Marker Interface, Wrapper Classe and Adapter Class
• Classes like Math, StrictMath, Scanner, Console
• Java IO: Important classes in IO, NIO.
• Reading and writing XMLs in java. Type of parsers – SAX, DOM and STAX.
• Java UI: AWT vs Swing, Different Layouts, Event handling, Calback methods
• Serialization, Transient keyword
• Multithreading – Runnable vs Thread, How to write a thread, difference between run and start method.
• Java5 Concurrency and advanced threading – Callable, Future, Executors, Thread pooling, Locks and Conditions
• Collection and Generics – Map, Set and List; Conventional Questions like ArrayList vs Vector, HashTable vs HashMap etc; Comparator and Comparable; Important collection classes.
• Methods of java.util.Collections – Synchronizing a collection, Creating views
• JDBC: The JDBC code, Type of JDBC Drivers, Type of Statements, execute, executeUpdate and executeQuery

We can discuss these further in case of queries/suggestions. Feel free to comment and add in case I missed something.

Enjoy learning,

Kamlesh