Question { 6840 }

what is wrapper class and its uses?

Answer

A class enclosed or Wrapped the primitive data type is
called wrapper class.

Number class is the super class for Wrapper class. subclass
of Number classes are Byte,Short,Intger,Long,Float,Double,
Character

primitive values Wrapper class

byte Byte
short Short
int Integer
long Long
float Float
char Character

Mostly the wrapper classes are used to pass the date thru
networks/serializable.

Question { Photon, 8499 }

what is the life cycle of jsp?

Answer

jsp life cycle:
===============
1.Page translation - automatically translate the .jsp file
in .java(servlet)file
2.Compilation - automatically compile the .java(servlet)
file and create .class file .
3.Loading - load the compiled servlet into container.
4.Create instance - create instance for loaded servlet
(.java)
5.call jspInit method. (call only one time)
6.call _jspService method
7.call jspDestroy method.(call only one time)

Question { 7017 }

how exactly garbage collection take place?

Answer

Variable/object
1. is eligible for garbage collection when no object refers
to it.
2. Is eligible when its reference is set to null i.e
objName=null.
3. referred by method variables or local variables are
eligible for garbage collection when they go out of scope.

Question { 9902 }

How to make class immutable

Answer

Steps:
1. Create class as final class
2. Make all the properties i.e instance variable as final.
3. Avoid or make the least access for the setter method
for properties.

Question { TCS, 23904 }

Can we declare static variables in JSP page.

Answer

In Declaration tag (<%! -- %>), you can able declare the
static variable,class, define methods.

Question { 6434 }

If there is no implementation of MARKER INTERFACE in java.
Then how compiler come to know about specification.

Answer

Every marker interface has some specific functionality and
no methods in that interface.

Ex:
Searializable - Persistent purpose
Clonnable - for cloning the object
SingleThreadedModel - only one object can be create.