Core Java Interview Questions

static variable can not be serialized.... please follow find below example. Test3==> "java package a.b.c.d.e; import java.io.FileInputStream; import java.io.FileOutputStream;...

No static variables can't be serialzed......

any doubts, let me know i can give an example???

1. Object is super class for all java classes.

2. even if someone want to make a class as subclass of CLASS class, he cant because class class is declared as final. so it can not be inherited

java.lang.Object is the super class of all classes and NOT Class class

vinny

javax.sql provides connection pooling ,distributed transaction,disconnected rowsets

java.sql.* package is used for the basic jdbc connections.
javax.sql.* package is used for the advance jdbc.  Advance is connection pooling, rowsets...ect.

We can create an object in java by six ways.......

1.new operator
2.class.forName
3.Factory Method
4.Cloning
5.Deserialization
6.Reflection API

In 5 ways

1. New operator
2. New instance
3. Clone
4 Factory method
5 De-Serialization

java does not support multiple parenting.

Pradeep, Does java supports Switch/Case trype of branching? Is this an OOPS concept?

Checked Exception represents the External Failure while Unchecked Exception represents the Internal failure.

checked exceptions must be handeled.That is, a try-catch must either be nested around the call to the method that throws the exception.The compiler will throw an ...

Array is a set of related data type and static whereas vector is a grow able array of objects and dynamic

AL-non legecy/methods are not sysnchronized
Vector-legecy/method are synchronized

All the methods declared inside an interface are abstract whereas abstract class must have at least one abstract method and others may be concrete or abstract. b) In abstract class, key word abstract...

First ask yourself the question as to why is static used? Static helps us use those static members of the class directly, without creating an object. Second of all the outer classes are already perc...

It will compile but gives error at run time......

The complier will throw error that there is no main()  method. main() should be public always please note.

if you have an infinite loop that keeps on doing things that take up memory (like creating objects).

We all know Java automatically garbage collects unused objects. But you must remember that an object is considered as unused only when the object no longer referenced. That means a referenced class continues to exist and to take up memory space even if it is not used.

Prepared statements can also execute a sql block or stored procedure.

But advantage of callable statement is it has registerOutParameter option.

If you want the OUT param value, you need to use CallableStatement alone.

PreparedStatement:
Use when you plan to use the SQL statements many times. The PreparedStatement interface accepts input parameters at runtime

CallableStatement:
Use when you want to access database stored procedures. The CallableStatement interface can also accept runtime input parameters.

The correctness and consistency of stored data is known as integrity of data.

Ans:2

You are right Sandeep.

But I guess, Sadashivrao did not set a classpath if he is executing this program on command prompt.

You can set classpath by:(if u saved Return.java in temp folder)

C:Documents and Settingsx.yDesktoptemp>set classpath=%classpath%;
C:Documents and Settingsx.yDesktoptemp

gc called by jvm we dont hav any contol

When Java was originally developed, the JDK shipped with a mark-and-sweep garbage collector. A mark-and-sweep garbage collector proceeds in two phases: Mark: identifies garbage objects Sweep: reclaims...

we cant create the instance of abstract class ..here we need sub class which extended this class .we can have ref var of abstract class

First thing first, An abstract class without any abstract method means you are loosing the main intent fo abstractness, why we are making abstract class is to provide some of common implementation and...

Compilation error . System.out.println() is the syntaz not system.Out.Println

arrayOutOfBoundException

Implement the Comparator Interface for the Employee Class. Then customize your sort in the implemented method from interface

Implement Comparable interface for the class Employee, customize your require in the implemented method from interface