Core Java Interview Question, Interview Question

This page discusses - Core Java Interview Question, Interview Question

Core Java Interview Question, Interview Question

Core Java Interview Question Page 2

     

Question: Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written?

Answer: Yes, it does. The FileNoFoundException is inherited from the IOException. Exception's subclasses have to be caught first.

Question: Can an inner class declared inside of a method access local variables of this method?

Answer: It's possible if these variables are final.

Question: What can go wrong if you replace && with & in the following code: String a=null; if (a!=null && a.length()>10) {...}

Answer: A single ampersand here would lead to a NullPointerException.

Question: What's the main difference between a Vector and an ArrayList

Answer: Java Vector class is internally synchronized and ArrayList is not.

Question:
When should the method invokeLater()be used?

Answer: This method is used to ensure that Swing components are updated through the event-dispatching thread.

Question: How can a subclass call a method or a constructor defined in a superclass?

Answer: Use the following syntax: super.myMethod(); To call a constructor of the superclass, just write super(); in the first line of the subclass's constructor.

For senior-level developers:

Question: What's the difference between a queue and a stack?

Answer: Stacks works by last-in-first-out rule (LIFO), while queues use the FIFO rule

Question: You can create an abstract class that contains only abstract methods. On the other hand, you can create an interface that declares the same methods. So can you use abstract classes instead of interfaces?

Answer: Sometimes. But your class may be a descendent of another class and in this case the interface is your only option.

Question: What comes to mind when you hear about a young generation in Java?

Answer: Garbage collection.

Question: What comes to mind when someone mentions a shallow copy in Java?

Answer: Object cloning.

Question: If you're overriding the method equals() of an object, which other method you might also consider?

Answer: hashCode()

Question: You are planning to do an indexed search in a list of objects. Which of the two Java collections should you use: ArrayList or LinkedList?

Answer: ArrayList

Question: How would you make a copy of an entire Java object with its state?

Answer: Have this class implement Cloneable interface and call its method clone().

Question: How can you minimize the need of garbage collection and make the memory use more effective?

Answer: Use object pooling and weak object references.

Question: There are two classes: A and B. The class B need to inform a class A when some important event has happened. What Java technique would you use to implement it? 0

Answer: If these classes are threads I'd consider notify() or notifyAll(). For regular classes you can use the Observer interface.

Question: What access level do you need to specify in the class declaration to ensure that only classes from the same directory can access it?

Answer: You do not need to specify any access level, and Java will use a default package access level .

Tutorials

  1. Core Java Interview Question Page 1
  2. Core Java Interview Question Page 3
  3. Core Java Interview Question Page 8
  4. Core Java Interview Question, Interview Question
  5. Core Java Interview Question, Interview Question
  6. Core Java Interview Question, Interview Question
  7. Core Java Interview Question, Interview Question
  8. Core Java Interview Question, Interview Question
  9. Core Java Interview Question, Interview Question
  10. Core Java Interview questions and answers
  11. Core Java Interview Question, Interview Question
  12. Core Java Interview Question, Interview Question
  13. Core Java Interview Question, Interview Question
  14. Core Java Interview Question, Interview Question
  15. Core Java Interview Question, Interview Question
  16. Core Java Interview Question, Interview Question
  17. Core Java Interview Question, Interview Question
  18. Core Java Interview Question, Interview Question
  19. Core Java Interview Question, Interview Question
  20. Core Java Interview Question, Interview Question
  21. Core Java Interview Question, Interview Question
  22. Core Java Interview Question, Interview Question
  23. Core Java Interview Question, Interview Question
  24. Core Java Interview Question, Interview Question
  25. Core Java Interview Question, Interview Question
  26. Core Java Interview Question, Interview Question
  27. Core Java Interview Question, Interview Question
  28. Core Java Interview Question, Interview Question
  29. Core Java Interview Question, Interview Question
  30. Core Java Interview Question, Interview Question
  31. Core Java Interview Question, Interview Question
  32. Core Java Interview Question, Interview Question
  33. Core Java Interview Question, Interview Question
  34. Core Java Interview Question, Interview Question
  35. Core java Interview Questions