Java Interview Questions  


What is the difference between an Interface and an Abstract class?

What is the purpose of garbage collection in Java, and when is it used? 

Describe synchronization in respect to multithreading.

Explain different way of using thread? 

What are pass by reference and passby value?

What is HashMap and Map?

Difference between HashMap and HashTable?

Difference between Vector and ArrayList?


Difference between Swing and Awt?


What is the difference between a constructor and a method?

What is an Iterator?

State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships on declared items qualified by these modifiers.


What is an abstract class?


What is static in java?


What is final?

 

  
Java Collection Interview Questions  

What is the Collections API?

What is the List interface? 

What is the Vector class?
   
What is an Iterator interface? 
   
Which java.util classes and interfaces support event handling?
   
What is the GregorianCalendar class?
   
What is the Locale class?
  
What is the SimpleTimeZone class?
   
What is the Map interface?
   
What is the highest-level event class of the event-delegation model?
   
What is the Collection interface?
   
What is the Set interface?
  
What is the typical use of Hashtable?
  
I am trying to store an object using a key in a Hashtable. And some other object already exists in that location, then what will happen? The existing object will be overwritten? Or the new object will be stored elsewhere?

What is the difference between the size and capacity of a Vector?
  
Can a vector contain heterogenous objects?

 
Struts Interview Questions  


What is Struts?

What is Jakarta Struts Framework

What is ActionServlet

How you will make available any Message Resources Definitions file to the Struts Framework Environment?

What is Action Class?

What is ActionForm?

What is Struts Validator Framework?

Give the Details of XML files used in Validator Framework?

How you will display validation fail errors on jsp page?

How you will enable front-end validation based on the xml in validation.xml?

How to get data from the velocity page in a action class?

 
DB Interview Questions

What is SQL? 

What is SELECT statement?

How can you compare a part of the name rather than the entire name?

What is the INSERT statement?

How do you delete a record from a database?

How could I get distinct entries from a table?

How to get the results of a Query sorted in any order?

How can I find the total number of records in a table?

What is GROUP BY?

What is the difference among "dropping a table", "truncating a table" and "deleting all records" from a table?

What are the Large object types suported by Oracle?

Difference between a "where" clause and a "having" clause ?

What is the difference between a primary key and a unique key?

What are cursors? Explain different types of cursors. What are the disadvantages of cursors? How can you avoid cursors?

What are triggers? How to invoke a trigger on demand?

What is a join and explain different types of joins.

What is a self join?

 

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Sandeep Joshi
Mathematics, Technology and Programming are my passion. I am a part of Java Ecosystem and through this blog, I contribute to it. I am here to blog about my interests, views and experiences.
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I feel proud to be listed as a "National Memory Record Holder" in the Limca Book of Records, 2009 and have attempted for an International Memory record in the Guiness Book of Records. I can remember the value of PI upto 10,000 digits after the decimal (3.1415.....). You can contact me on javagenious.com(At)gmal.com ; I would like to hear from you :)