1 Object Oriented Programming (OOP)
1.1 Encapsulation
1.2 Polymorphism
1.3 Inheritance
1.4 Abstraction
1.5 Differences between Abstraction and Encapsulation
2 General Questions about Java 3
2.1 What is JVM ? Why is Java called the Platform Independent Programming Language?
2.2 What is the Difference between JDK and JRE ?
2.3 What does the “static” keyword mean ? Can you override private or static method in Java ?
2.4 Can you access non static variable in static context ?
2.5 What are the Data Types supported by Java ? What is Autoboxing and Unboxing ?
2.6 What is Function Overriding and Overloading in Java ?
2.7 What is a Constructor, Constructor Overloading in Java and Copy-Constructor.
2.8 Does Java support multiple inheritance ?
2.9 What is the difference between an Interface and an Abstract class ?
2.10 What are pass by reference and pass by value ?
3 Java Threads 6
3.1 What is the difference between processes and threads ?
3.2 Explain different ways of creating a thread. Which one would you prefer and why ?
3.3 Explain the available thread states in a high-level.
3.4 What is the difference between a synchronized method and a synchronized block ?
3.5 How does thread synchronization occurs inside a monitor ? What levels of synchronization can you
apply ? . . .
3.6 What’s a deadlock ?
3.7 How do you ensure that N threads can access N resources without deadlock ?
4 Java Collections
4.1 What are the basic interfaces of Java Collections Framework ?
4.2 Why Collection doesn’t extend Cloneable and Serializable interfaces ?
4.3 What is an Iterator ?
4.4 What differences exist between Iterator and ListIterator ?
4.5 What is difference between fail-fast and fail-safe ?
4.6 How HashMap works in Java ?
4.7 What is the importance of hashCode() and equals() methods ?
4.8 What differences exist between HashMap and Hashtable ?
4.9 What is difference between Array and ArrayList ? When will you use Array over ArrayList ?
4.10 What is difference between ArrayList and LinkedList ?
4.11 What is Comparable and Comparator interface ? List their differences.
4.12 What is Java Priority Queue ?
4.13 What do you know about the big-O notation and can you give some examples with respect to
different data
Structures ?
4.14 What is the tradeoff between using an unordered array versus an ordered array ?
4.15 What are some of the best practices relating to the Java Collection framework ?
4.16 What’s the difference between Enumeration and Iterator interfaces ?
4.17 What is the difference between HashSet and TreeSet ?
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