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JSP jspinit() method
Will you be able to override jspinit() methods? Justify
apgenius
- Jan 10th, 2010
Yes, we can. Infact its actually why it's there. We override the jspinit() when we want to make some initial database connections etc..Same goes for jspdestroy(), but _jspService() can't be overriden.
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Need of Method Overloading
What is the need of method overloading? What would happen if this feature is not present in Java?
msrmsr
- Oct 4th, 2010
In Java one of the main concept is polymorphismpoly means many..taking many form with existing one.if we use a method callled add();add(int x,int y) we can? add 2 integersadd(float x,float y)we can a...
yogesh249
- Jan 30th, 2010
It is simple. Overloading is required, if you want a particular method to change its behavior based on the parameters passed.Suppose you have a sum functionSum(int i, int j)This will add two inte...
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Object Class
When you declare a class, why does it automatically extends to object class? Give 2 reasons.
mani.sivapuram
- Mar 11th, 2011
When preparing the Java by JavaPeople they thought like every object what we prepare should have some common property so that we can do some basic operations like for example clone() method. So ...
anandkumarjha
- Aug 9th, 2010
Object class is the super class of all the classes provided by java.lang package.? And I think you know that all the basic functions to write a program like println() are the content of the class...
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Runnable Method
If Thread class contains run() method then why we are using run() method by implementing the runnable method in the Thread?
muralidhar.9e
- Sep 29th, 2010
Actually Runnable interface has the method run(). Every thread Object call the start() method to run the thread run() method. So Every run() method have their own implimentation.So we should write their own run() method thread code.
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Size of an Object
How to find size of an object?
rohodium
- Sep 7th, 2010
As there is no predefined method in Java. We can use an indirect approach. We can calculate the memory of an object by taking the difference of the amount of memory used by the program before creatin...
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How to find out classes present in predefined packages?
Kumar
- Jul 24th, 2011
By referring the RT.jar file in jre folder of jdk software installation
vasavimonika
- Mar 5th, 2011
By going through the API we can find out all the prefined classes as well as interfaces and what are all the methods can support by that class.
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System is a class or a package?
class Test
{
public static void main(String... a)
{
System.out.println("hello world");
}
}
In the above code if we write "s" of String class in lowercase, it gives an error of class not found, but if we write "S" of "System" class in lower case it gives an error package not found.
why?amrutabhavana
- Sep 4th, 2011
System is class.it belongs to the lang package."System.out.println" means println is a method which is called by out object of system class.
Prabha
- Aug 10th, 2011
System is a class which is available in lang package and we need not to create object. When we give System as system compiler searches in the package and gives an error.
String is also a class and we can create objects to handle character strings and it is a reference datatype -
What is the purpose of hash code in Java?
rajesh
- Feb 28th, 2012
At the time of creating object constructor will be execute it will tell the size of memory to the JVM and JVM will tell to the heap manager and heap manager will create the memory at that time heap manager will create one unique id is called hash code
amrutabhavana
- Sep 4th, 2011
Hash code is nothing but byte code. The byte code produced in Java is independent of architecture. We can run this byte code in any platform. By this we can say that Java is platform independent.
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Java code to set column width in CSV file
Can someone help on how to set the column width in CSV file using javacode.
I have used FileWriter class to upload data into the csv file. Results are getting populated properly but csv file showing results with default column width. Is there a way we can set the width of the column dynamically based on result length or set fixed length?
Dusmanta
- Nov 12th, 2014
Use Apachae POI jar for this HSSFSheet sheet = workBook.createSheet("testXls");
Code- // Code to Auto size the column widths
- for(int columnPosition = 0; columnPosition< 5; columnPosition++) {
- sheet.autoSizeColumn((short) (columnPosition));
- }
Abhishek Mishra
- Oct 8th, 2014
Account,LastName,FirstName,Balance,CreditLimit,AccountCreated,Rating 101,Reeves,Keanu,9315.45,10000.00,1/17/1998,A 312,Butler,Gerard,90.00,1000.00,8/6/2003,B 868,Hewitt,Jennifer Love,0,17000.00,5/25/1...
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Explain Object Construction in simple terms
In Java, object types (i.e., classes) must be explicitly constructed for initialization. Explain object construction. Then, state the name of the mechanism for object destruction, and explain in simple terms how it works.
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Explain White box testing related to Java ?
Abhishek Mishra
- Oct 5th, 2014
White Box Testing is a software testing method in which the internal structure/design/implementation of the item being tested is known to the tester. The tester chooses inputs to exercise paths throug...
ABHISHEK MISHRA
- Oct 5th, 2014
White box testing is the detailed investigation of internal logic and structure of the code. White box testing is also called glass testing or open box testing. In order to perform white box testing o...
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What is lock in thread
Vishal
- Jan 2nd, 2018
When we are working with multiple threads, we have to make sure multiple threads are working on synchronized object otherwise different threads might see different values for same variables. In order...
sandychops
- Feb 24th, 2015
Lock is a thread synchronization mechanism similar to synchronized blocks. From Java 5 the package java.util.concurrent.locks contains several lock implementations which we can use to achieve synchron...
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What is the List interface
The List interface provides support for ordered collections of objects.
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How does Java handle integer overflows and underflows
It uses those low order bytes of the result that can fit into the size of the type allowed bythe operation.
sandy2789
- Jan 13th, 2009
Difference Between Over Flow & Under Flow (JAVA) over flow = ex : array> [0][1][2][3][4] onl...
Sony V George
- Apr 5th, 2007
In java there is no point of overflow and underflow, it was there in C. For avoiding that java introduces type casting. Java will allow some more space from the defult space of primtive type.
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What is the difference between the >> and >>> operators
The >> operator carries the sign bit when shifting right. The >>> zero-fills bits that havebeen shifted out.
Suraj Patil
- Aug 16th, 2014
When you deals with >> operator, only shifting is done by moving count times towards right without any replacement by zero. but when you deals with >>> operator them like >> this operator but only di...
infant
- Oct 5th, 2005
While dealing with (+)ve numbers there is no difference between >>> and >> operators.Both operators shift zeros into the upper bits of a number.The difference arises when dealing with (...
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What is the range of the char type
The range of the char type is 0 to 2^16 - 1.
anita
- Apr 14th, 2015
According to me size of char type is 2^15-1..
sentientmachine
- Mar 9th, 2011
In java, the range of a char type is 0 to 65535 or0 to +((2^16)-1)Getting java to print out the MIN_VALUE and max value is tricky because the characters at position 0 and 65535 are unprintable. ...
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What is the purpose of finalization
The purpose of finalization is to give an unreachable object the opportunity to performany cleanup processing before the object is garbage collected.
lwpro2
- Mar 13th, 2011
Actually in addtion to perform some clean up process, it can also be used to bring this object to life, by making it accessible again.
sagar.singh
- Aug 23rd, 2007
Java provides a method called finalize( ) that you can define for your class. Heres how its supposed to work. When the garbage collector is ready to release the storage used for your object, it ...
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What invokes a thread's run() method
After a thread is started, via its start() method or that of the Thread class, the JVMinvokes the thread's run() method when the thread is initially executed.
RV
- Oct 7th, 2017
If we havent define run() method within child Class... and we call start() mathod throght child object...
and o/p will be Blank screensubashrivasudevan
- Nov 22nd, 2008
Start method invokes it.It may or may not get executed immediately.
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What is the difference between applet and application
paul_jit
- May 13th, 2009
1. An Applet is a Java program running inside a web browser, while a Frame is a kind of window.2. An Applet may open a Frame, or it might just run inside its panel.
Java Interview Questions
Ans