43 Advanced Java Programming Interview Questions

Of all the software development languages out there, Java is considered the best paying in the industry. The Java industry in itself is worth somewhere between $12 billion and more. If this is a career you are looking at pursuing, the following list of Java Programming interview questions will help you prepare.

Can an inner class declared inside of a method access local variables of this method?
Can you call one constructor from another if a class has multiple constructors?
Describe the wrapper classes in Java.
Difference between HashMap and Hashtable?
Explain in your own words the “bottom line” benefits of the use of an interface.
Explain the usage of Java packages.
Explain the usage of the keyword transient?
How could Java classes direct program messages to the system console, but error messages, say to a file?
How do you deal with dependency issues?
How do you force the garbage collection?
How do you know if an explicity object casting is needed?
How do you sort Java object using Comparator?
How do you Sort objects on collection?
How do you test your code?
How does HashMap work in Java?
How would you make a copy of an entire Java object with its state?
If you needed to provide a GUI for your Java program, how would you go about it?
What access level do you need to specify in the class declaration to ensure taht only classes from the same directory can access it?
What are some advantages and disadvantages of Java sockets?
What are the differences between interfaces, abstract classes, classes, and instances?
what are the differences between Map, Hashtable, Hashmap, Treemap, ConcurrentHahMap, LinkedHashMap?
What do you understand by Synchronization?
What does synchronized do? Tell me how to use it to set a variable just one wtihout any race conditions?
What does the static keyword mean, and where can it be used?
What is collection API?
What is difference between Vector and ArrayList?
What is the difference between fail-fast and fail-safe Iterators?
What is the difference between HashMap and HashSet?
What is the difference between Iterator and Enumeration?
What is the difference between private, protected, and public? (Reference to keywords and privledges)
What is the difference between Set and List in Java?
What is the difference between Synchronized Collection and ConcurrentCollection?
What is type erasure?
What’s the difference between a queue and a stack?
What’s the difference between an interface and an abstract class? Discuss the similarities.
What’s the different between constructors and normal methods?
Whats the main difference between a Vector and an ArrayList?
When and why are getters and setters important?
When do you use ConcurrnetHashMap in Java?
Why would you use a synchronized block vs. synchronized method?
Write a program to implement binary search algorithm?
Write a program to sort numbers using quick sort?
You want to create a simple class that just has three member variables. Tell me how’d you do this?

In the 1980s, only 1 in every 3 computer science students were female. Now a days, 1 in every 10 are present. The average computer program can make over $70,000 a year. More interesting facts about the code developer industry are outlined below in the following infographic.

Code Developer Industry Statistics