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What is the Output of the following Java Program
public interface I1{Static String x="inside I1";public void someMethod();}class A implements I1{ public static void main(String args[[]){ System.out.println("Calling I1 var ..."+I1.x);}}
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abuthahir.d- Member Since Jan-2008 | Apr 14th, 2008
Compilation error due to 2 reasons.
1. All variables defined in the Interfaces are implicitly public static final. So need not specify "Static" in interface.
2. If any of the member functions of a Interface is not Overriden , a compilation error will be thrownshanu_rastogi
- Feb 3rd, 2010
It is right that you dont need to explicitly define a varible static but if you do so then it will not give compliler error..
sarojmohanty
- Nov 19th, 2009
Compilation error will come because you must have to override the abstract method of the implememted interface. After the implementation of the abstract method the program will compile and run properly and print "inside l1".
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Will there be a performance penalty if you make a method synchronized? If so, can you make any design changes to improve the performance
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Answered by: Faisal Ghauri
- Jul 24th, 2005
Performance does take a hit when using synchronization. I think the way to reduce this hit is to synchronize only a block of code that will be accessed by threads and not synchronize the entire method.
sumeesudha
- Feb 6th, 2010
There is degradation in performance when you make a method synchronized. Even when a program contains only a single thread running on a single processor, a synchronized method call is still slow...
sripatnaiky
- Feb 4th, 2010
The Synchronization may be useful in avoiding the deadlock, helpful in maintaining the consistent object state etc,. Only one thread will be accessed at a time by acquiring lock on the synchronized bl...
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Is it possible to serialize a single member in a class?
suppose i have 2 members in my class can i serialize a single member? Is there any way to do that?
ashutoshwithashi
- Feb 13th, 2010
Yes, it is possible to serialize a single member in a class from the externializable interface as we can control the searization process with the and by searilizing the single memer through writeExternal() and readExternal() method we can do it.
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Difference: Java Beans, Servlets
lieutaryan
- Feb 13th, 2010
Servlets are java classes designed to serve content from the web, like a web server serves HTML pages. A servlet is used to receive requests, process them, and then return responses to the program tha...
prem kumar
- Jul 29th, 2006
HIWhat is meant by reusable? we can use instance of a class as we want more times. Then, and diff between bean and class.Prempremkumar.cm@gmail.com
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Run the Tomcat Server
Hi, Is it possible to run the 2 tomcat servers simultaneously with different ports.Some times it's working. some times its not running,Anybody can help me to solve this problem.Thxregards'Punitha.R
DVishwakarma
- Feb 24th, 2010
Multiple instances of tomcat server can be run on any machine using the following steps.Copy zip installer from Apache.orgunzip in C:/Tomcatset Environment variable as CATALINA_HOME C:/TomcatJDK_HOME ...
uncer
- Jan 17th, 2010
Follow these step;1. Set JAVA_HOME=C:/JDK2 SET CATALINA_HOME=C:/TOMCAT3. CLASSPATH=C:/servlet.jav;.;jsp.jar;Then go into tomcat folder search servlet.jar copy short cut paste at desktop and double click.
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What is the use of Empty Interface?
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Inherit Super Class Without Extends Statement
If Object is the super class of all classes, how it is inherited without extends statement?
santosh.dhulipala
- Mar 5th, 2010
During the compilation process our JVM checks whether we are extending any class, if not it will will extend the object, which we know that is super class of all classes, which is defaultwe can check ...
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1) write a program that singleton objects returns two instances?
Give me answer
ksureshbabu
- Mar 5th, 2010
class Singletones implements Serializable{ /** * */ private static final long serialVersionUID = 6240073482570369797L; &...
Jagdeep Grewal
- Nov 8th, 2005
public class CSingleton { private static CSingleton inst= null;private static int count=0;protected CSingleton() { &n...
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Abstract Class or Method
Can we make use of "this" keyword reference inside a abstract method or abstract class? Explain
java indian
- Mar 10th, 2010
Yes we can use "this" key word in Abstract class or methods,Here we have simple sample used of this key in abstract.abstract class ab { int j;void meth() { this. j=10; ...
yogesh249
- Jan 24th, 2010
Yes that is true that we cannot create object of an abstract class. But the question is "Can we use this keyword in an abstract class."The answer is YES we can..Have a look at the following ...
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How many JVM's we can run in a system?
phanibhushan.g
- Mar 12th, 2010
We can run as many JVMs as possible at the same time depending on the memory (RAM). Also the JVM instance can belong to any one of the java implementors like Sun JDK, JRockit etc parallely. For using ...
mytramesh
- Apr 7th, 2006
Hai Friends you have to remember one thing.The Jvm is one.Butwe can have mamy jvm instances. you open five commmand prompts and do java programs in all command prompts.All will execute.For ...
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Explain Servlet and JSP life cycle
nalindascjp
- Mar 4th, 2010
A Servlet is a Java class which faclitates a web developer to write dynemic web pages. JSP is the presentation componant that used with Servlets to make a page dynamic. Generally a JSP is a HTML docum...
sripatnaiky
- Feb 4th, 2010
Life cycles are pretty same, as the JSP will be translated into a servlet during the translation phase, the important point to be considered here is if we include another JSP by making use o...
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Whether a Class,Method can be garbage collected or not?How?
MMK143
- Mar 28th, 2010
Class and Method are not garbage collected because class and methods are the predefined instruction formats for developing an object oriented programming.
umesh_kilkile
- Mar 23rd, 2010
No. Class and methods aren't garbage collected.Because Class is a logical construct in that we write methods or logics.When we run Java program, class gets loaded in main memory that is RAM and method...
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Mutithreading
How synchronization can be done for multithreading environment without using the "synchronized" keyword?
Aqan12
- Apr 13th, 2010
Use java.util.concurrent package Lock mylock;try{ mylock.lock(); //critical section}finally{ mylock.unlock();} Also: try a lock with a timeout trylock() wait for some condition: condition.await() these could come handy to avoid the deadlock situations.
kvrprasadmca
- Apr 7th, 2010
We can achieve by using thread-safe collection objects like vector and all.
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Why java does not have multiple inheritance?but in c++ ?
jimmy514in
- Apr 22nd, 2010
Multiple inheritance in Java is supported by the use of Interfaces.You do not have direct multiple inheritance because Java is a programming language which is kept simple.And using multiple inheritanc...
ashish_setia
- Oct 2nd, 2006
yes this is absoluetly true, in java we dont hav multiple inhet. actually multiple inheritance means a drive class is having mare than one base class. just as it will create the popular diomound probl...
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1)what are the other ways to create an object otherthan creating as new object?
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What are advantages and usage of static block?
pdommara
- May 28th, 2010
The above answers are missing important point that is it even runs before your class constructor.
vinaymudgil007
- Jun 10th, 2008
static block is executed whenever a class is loaded by the JVM.....hence in case you want certain code to executed or say some objects of a class avaliable to ur application as soon as the application starts you can put in the relevant code there....vinny
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Exception on finalize ()?
If Exception occurs in finalize() what happened to garbage collector? It will run or not? Explain
asanse
- May 27th, 2010
Any exception thrown by finalize() during garbage collection halts the finalization but is otherwise ignored.
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Market interface means interface which have no methods. Then why we call the Runnable interface as a marker interface, even though it has run() method
pdommara
- May 31st, 2010
Who said Runnable interface is marker interface. It has method called run(). It is not a marker interface.
piscesinblues
- Jan 22nd, 2007
Up to my knowledge marker interface is an interface having no methods, so Runnable interface is an interface having run() method, so definetly it is not a marker interface, if so the case, please post the complete description regarding that and let me know
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When you have an object passed to a method and when the object is reassigned to a different one, then is the original reference lost
Aqan12
- Jun 4th, 2010
Primitives are always passed by value.Objects: Passed by value of reference. i.e. a copy of reference is passed into the method. Any changes to the reference itself will not be visible outside the met...
Scorpio_
- May 7th, 2010
Mr Ashutosh Gupta,Java is pass-by-value. For primitives, you pass a copy of the actual value. For references to objects, you pass a copy of the reference. You never pass the object. All objects are stored on the heap. Always http://www.javaranch.com/campfire/StoryPassBy.jsp
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Serialization Process
Explain the use of serialization process in real time projects?
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Sarje- Member Since Aug-2009 | Aug 28th, 2009
Serialization is the process of writing the state of an object to a byte stream. This is useful when you want to save the state of the object (content of the object) to a persistent storage area, such a file.
For example if you want to maintain record of the temprature on a particular place at every hour then you can serialize your object and save the temprature at every hour in a file.
Only an object that implements the java.io.Serializable interface can be saved.dh_maan
- Jun 6th, 2010
The use of serialization process in real time project is to transfer the object over the network.
winoth4
- Oct 28th, 2009
Serialization is writing the state of the object to a byte stream. This is useful when you want to save the state of the object in a persistent ?storage such as file.
Core Java Interview Questions
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