Infosys Core Java Placement Papers - Infosys Core Java Interview Questions and Answers
Q1. What Is A Thread?
Thread is a block of code that could execute concurrently with different threads inside the JVM.
Q2. What Is Singleton?
It is one of the layout sample. This falls in the creational sample of the layout pattern. There might be handiest one example for that complete JVM. You can gain this by means of having the non-public constructor within the magnificence.
For eg.,
public magnificence Singleton
personal static very last Singleton s = new Singleton();
private Singleton()
public static Singleton getInstance()
return s;
// all non static strategies …
Q3. What Is The Purpose Of Assert Keyword Used In Jdk1.Four.X?
In order to validate positive expressions. It correctly replaces the if block and routinely throws the AssertionError on failure. This keyword should be used for the critical arguments. Meaning, without that the approach does nothing.
Q4. What Is The Protocol Used By Rmi?
RMI-IIOP
Q5. Can You Instantiate The Math Class?
You can’t instantiate the maths elegance. All the methods on this magnificence are static. And the constructor is not public.
Q6. Does The Jdbc-odbc Bridge Support Multiple Concurrent Open Statements Per Connection?
No
Q7. Is Jdbc-odbc Bridge Multi-threaded?
No
Q8. What Interface Do You Implement To Do The Sorting?
Comparable
Q9. What Is The Algorithm Used In Thread Scheduling?
Fixed precedence scheduling.
Q10. What Is The Use Of Serializable?
To persist the kingdom of an item into any perminant storage device.
Q11. What Do You Mean By Rmi And How It Is Useful?
RMI is a far flung method invocation. Using RMI, you could paintings with far off object. The characteristic calls are as though you are invoking a nearby variable. So it gives you a impression which you are operating actually with a object that is living inside your very own JVM even though it is somewhere.
Q12. What Is The Major Difference Between Linkedlist And Arraylist?
LinkedList are meant for sequential getting access to. ArrayList are supposed for random gaining access to.
Q13. What Is The Final Keyword Denotes?
Very last key-word denotes that it's far the very last implementation for that method or variable or magnificence. You can’t override that method/variable/elegance any extra.
Q14. What Is Nested Class?
If all the strategies of a internal class is static then it is a nested magnificence.
Q15. What Is Composition?
Holding the reference of the other class within a few different elegance is referred to as composition.
Q16. What Is The Significance Of Listiterator?
You can iterator from side to side.
Q17. What Are The Different Driver Types Available In Jdbc?
A JDBC-ODBC bridge
A native-API in part Java technology-enabled motive force
A internet-protocol fully Java generation-enabled driver
A local-protocol absolutely Java era-enabled driving force For more records.
Q18. What Is Inner Class?
If the techniques of the internal class can best be accessed thru the instance of the inner magnificence, then it's far referred to as internal class.>
Q19. What Is Skeleton And Stub? What Is The Purpose Of Those?
Stub is a customer aspect illustration of the server, which looks after communicating with the remote server. Skeleton is the server side illustration. But that is no more officious… it is deprecated long earlier than in JDK.
Q20. What Is Hash-collision In Hashtable And How It Is Handled In Java?
Two extraordinary keys with the identical hash cost. Two one-of-a-kind entries could be kept in a single hash bucket to avoid the collision.
Q21. What Is A Marker Interface?
An interface without a strategies.
Example: Serializable, Remote, Cloneable
Q22. What Is Class.Forname() Does And How It Is Useful?
It hundreds the magnificence into the ClassLoader. It returns the Class. Using that you could get the example ( “magnificence-instance”.NewInstance() ).
Q23. What Is Driver Manager?
The basic carrier to manipulate set of JDBC drivers.
Q24. What Are The Methods In Object?
Clone, equals, wait, finalize, getClass, hashCode, notify, notifyAll, toString
Q25. What Is The Purpose Of Abstract Class?
It is not an instantiable class. It gives the concrete implementation for a few/all of the methods. So that they could reuse the concrete functionality with the aid of inheriting the abstract magnificence.
Q26. How Will You Get The Platform Dependent Values Like Line Separator, Path Separator, Etc., ?
Using Sytem.GetProperty(…) (line.Separator, path.Separator, …)
Q27. What Is Aggregation?
It is a special kind of composition. If you expose all the strategies of a composite elegance and path the technique name to the composite technique through its reference, then it's miles called aggregation.
Q28. What Is A Hashcode?
Hashcode fee for this object which is particular for each object.
Q29. What Is The Difference Between Interface And Abstract Class?
Abstract elegance described with techniques. Interface will declare handiest the strategies. Abstract lessons are very lots beneficial when there is a a few functionality throughout numerous classes. Interfaces are nicely suitable for the training which varies in capability but with the same approach signatures.
Q30. What Is The Eligibility For A Object To Get Cloned?
It ought to enforce the Cloneable interface
