Answers to “15 Must Know Java Interview Questions After 2 Years of Experience”

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• thanks for sharing . i think u missed a few important question

  what is a green thread in java.

  difference b/w clonable interface and remote interface

  what is a marker interface in java.

  • Hi Shashiranjan,

    1) green thread in java:

    There are two types of thereads are available . They are native threads and green threads.
    This native threads used by the os to perform the multi-threading and also these threads are managed by the kernal. The os use the pthread library to generate the native threads.

    The green threads are created by the programmer to execute our code in java. Sun microsystem proves only creation of green threads in java.

    It is not possiblt to swithch the native threads. But it is possiblt ot switch the green threads by using yield(),wait() and etc..

    2) Clonable interface:
    This Clonable marked interface is used to creating the exact copy of exiting object.

    Remote interface:

    Remote interface is used to creating the remote object that is shared by the mulitplt vertiul michines through RMI.

    3) marker interface in java:

    Which interface does not contain any methods those interfaces is called as marker interface or tagged interface. Thse interfaces are used to provide the some instruction to jvm.
    For example take the Serializable interface. Whenever any object provide the implementation to this interface the jvm allows the serialization on that object.

• here's some more:

  +1
  0
  vote
  Answer #1

  Hey!
  I’ll try to give you some examples, differentiated by the level of the candidate applying:

  **UPDATE**: If you are a junior java developer or an aspiring one, I strongly recommend you to take first the OCJP certification before going to an interview. This can increase your chances to succes big time, as well as your entry salary – proven and tested by myself! :)

  1) Junior java developer
  a) Basic ocjp (former scjp) questions:
  – What does static, final mean, purposes;
  – How many accesibility modifiers exist? Please describe them.
  – Why do you need a main method?
  – How many constructors can you have?
  – Define overwriting and overloading
  – Give java API implementations for overwriting and overloading
  – Describe the String class – unique properties
  – StringBuilder vs StringBuffer
  – Collections : please describe, give some examples and compare them to eachother
  – ArrayList vs Vector
  – HashMap vs HashTable
  – What’s a tree
  – What’s a map
  – Multithreading: describe the management in java
  – What’s a semaphone?
  – How many states are there for threads?
  – Describe the usage for synchronized word (2)
  – Serialization in java – a descrition and usage
  – Garbage collection in java – description and usage
  – Can you guarantee the garbage collection process?
  b) Simple design pattern questions:
  – Singleton please describe main features and coding
  – Factory please describe main features and coding
  – Have you used others? please describe them

  2) Intermediate and Senior level – depending on rate of good responses, additional questions to 1):
  http://centraladvisor.com/programming-2/java/java-developer-interview

• That's correct. Another similar question from my list of tricky Java questions is putting return statement in finally block which overrides return on try block.

  • Thanks for this post. This is really useful. here some Tricky Java Interview Questions with Answers

• Hi Shashiranjan,

  1) green thread in java:

  There are two types of thereads are available . They are native threads and green threads.
  This native threads used by the os to perform the multi-threading and also these threads are managed by the kernal. The os use the pthread library to generate the native threads.

  The green threads are created by the programmer to execute our code in java. Sun microsystem proves only creation of green threads in java.

  It is not possiblt to swithch the native threads. But it is possiblt ot switch the green threads by using yield(),wait() and etc..

  3) marker interface in java:

  Which interface does not contain any methods those interfaces is called as marker interface or tagged interface. Thse interfaces are used to provide the some instruction to jvm.
  For example take the Serializable interface. Whenever any object provide the implementation to this interface the jvm allows the serialization on that object.

• Problem : How Will you access the method of the sub class without creating the objcect of the SuperClass and the chances should be made into line between //....// area only... i.e. in single line. ( obj.add(); )

  public class SuperClass {
  public void add() {
  System.out.print("add() method from the Super Class");
  }
  }

  class SubClass extends SuperClass {
  public void add() {
  System.out.println("add() method from the SubClass.");
  }

  public static void main(String args[]) {
  SubClass obj=new SubClass();

  //..........................................................................//

  obj.add(); // add() method from SubClass.

  //..........................................................................//
  }
  }

• Thanks for sharing..
  This helps me a lot for time spent

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• What is the difference between checked and unchecked exceptions?

  Checked exceptions must be treated, while unchecked exceptions doesn't.

• Great Article Larry. Thanks. Recent Spring and Hibernate Interview Ques & Ans

• hi all,

  i very thanks to admin, and i feel it needs to add some more questions for our aspirants .

  thank you