Technical Discussion Forum

Interview questions

2012-01-05T06:52:00.000-08:00

These are few interview questions asked. The questions are based on Java and non technical. Some of the questions seems to be very simple and staight forward.

1. what is the difference between comments in java

Ans: 3 types of comments in java

a. // - which is single line comment
b. /* */ - which is to add a comment of more than one line, we can precede our comment using/*
c. /** */ -multiple line comments. Used for documentation purpose.

2. when there is a problem with the application, as a developer where we need to look at.

Ans : error logs and application server log files

3. How do you avoid deadlocks in a multithreaded enviornment?

Ans : first approach try to avoid synchronized where ever possible. If it is unavoidable, then code in such way that each thread should get lock & unlock in the same order or squence.

4. Write a Java program that:

- inputs a String from a user. Expect the String to contain spaces and alphanumeric characters only.
- capitalizes all first letters of the words in the given String.
- preserves all other characters (including spaces) in the String.
- displays the result to the user.

Answer : *
Approach : I have followed a simple approach. However there are many string utilities available
* for the same purpose. Example : WordUtils.capitalize(str) (from apache commons-lang)

/*****************************************************************************/
public static void main(String[] args) throws IOException{
System.out.println("Input String :\n");
InputStreamReader converter = new InputStreamReader(System.in);
BufferedReader in = new BufferedReader(converter);
String inputString = in.readLine();
int length = inputString.length();
StringBuffer newStr = new StringBuffer(0);
int i = 0;
int k = 0;
/* This is a simple approach
* step 1: scan through the input string
* step 2: capitalize the first letter of each word in string
* The integer k, is used as a value to determine whether the
* letter is the first letter in each word in the string.
*/

while( i < length){
if (Character.isLetter(inputString.charAt(i))){
if ( k == 0){
newStr = newStr.append(Character.toUpperCase(inputString.charAt(i)));
k = 2;
}//this else loop is to avoid repeatation of the first letter in output string
else {
newStr = newStr.append(inputString.charAt(i));
}
} // for the letters which are not first letter, simply append to the output string.
else {
newStr = newStr.append(inputString.charAt(i));
k=0;
}
i+=1;
}
System.out.println("new String ->"+newStr);
}
}
/*****************************************************************************/

5. How to reverse a string?

InputStreamReader inst = new InputStreamReader(System.in);
BufferedReader in = new BufferedReader(inst);
StringBuffer input = new StringBuffer(in.readLine());
System.out.println("Input String-->"+input);
System.out.print("reverse String-->");
System.out.print(input.reverse());

6. Palindrome program.

InputStreamReader instr = new InputStreamReader(System.in);
BufferedReader in = new BufferedReader(instr);
StringBuffer input = new StringBuffer(in.readLine());
StringBuffer reverseStr = new StringBuffer(input.reverse());
String inStr = input.toString().trim();
String outStr = reverseStr.toString().trim();
System.out.println(reverseStr);
if (inStr.equals(outStr)) {
//if (input.length() == reverseStr.length()) {
System.out.println("Palindrome");
//}
} else {
System.out.println("not Palindrome");
}

7. How does equals() method differs for String and StringBuffer classes?

String.equals() compares the 2 strings whereas StringBuffer.equals will return true only if compared with itself.

for comparision of strings we must use String.euqals() method or convert the StringBuffer to String and then compare.

Deploy a JSP in WebLogic 10.3.4

2011-06-07T07:41:00.000-07:00

Easy Steps :

1. Place the JSP in a new folder say Temp.

2. Create the war file using the command - jar -cvf TestJSP.war myJSP.jsp

3. Upload this war file from the weblogic deployments console
4. Access the JSP with URL - http://localhost:7001/TestJSP/myJSP.jsp

org.hibernate.QueryException: ClassNotFoundException: org.hibernate.hql.ast.HqlToken

2011-05-15T00:51:00.000-07:00

This is in sequence to my earlier post.

There are 2 ways as given below. But in my environment , I had to apply both the following steps as solution for above issue.

1. Changes in weblogic-application.xml

Add the antlr.* in the tag
----------------------------------

<prefer-application-packages>
        <package-name>antlr.*package-name>
    prefer-application-packages>

-------------------------------------

2. Changes in weblogic.xml

----------------------------------------
WebLogic has it's own version of ANTLR. Set the prefer-web-inf-classes element in weblogic.xml to true.

<weblogic-web-app>
  ....
  <container-descriptor>
    <prefer-web-inf-classes>trueprefer-web-inf-classes>
  container-descriptor>
  ....
weblogic-web-app>

------------------------------------------------

**** take care of the closing tags in the above XMLs by opening the XML file in any browser.

SCJP 6

2010-04-06T02:36:00.000-07:00

here are certain links for mock exams to prepare for scjp 6.0

1.http://faq.javaranch.com/java/ScjpFaq
2. http://faq.javaranch.com/java/ScjpMockTests
3. http://examlab.tk/

Examlab is tough, but if you get 50% of score, then it is almost sure that you can pass the SCJP

All the very best!!

ICICI has removed the NEFT charges & HDFC introduced NEFT charges:)

2010-01-16T22:33:00.000-08:00

Finally ICICI Bank not charging for the online transactions. That is good news for this new year!!!

But HDFC introduced the NEFT charges....

Real Estate comparison in Bangalore and Trivandrum

2010-01-16T22:16:00.000-08:00

This is a just my observation about the real estate market in Bangalore and Trivandrum. I recently bought a plot in Bangalore !( can not say it is in Bangalore as the place is very far away from Bangalore city.)

I purchased a 2064 sq ft in xxxxhalli :-) in Old Madras Road. It is very near to the Volvo factory in Bangalore. It cost me around 9 lacs. I am not sure whether it was a good deal or not. But later I found that the local people sold that area to the builders for about INR 225 per sq ft. This is a rough calculation. But having said that, I am getting the advantages of a fully built Township features at my place. So I am consoling myself. :)

I bought a flat in Trivandrum in 2008. It is a 3 BHK & cost me 34 lacs. Again at that time I was hoping to increase the price of flat in future, but now if I buy the same flat, there is hardly any change in price or no change.

But at that time I had inquired the price in Bangalore as well. The price is drastically changed during these period.

But I know that the market value for a city like Bangalore is nothing comparable to Trivandrum and again I will say that it is good that the flat price has not come down in Trivandrum even at the rescission time:)

What is the use of setting SerialVersionUID in serialization?

2009-07-18T07:27:00.000-07:00

The serialVersionUID is a universal version identifier for a Serializable class. Deserialization uses this number to ensure that a loaded class corresponds exactly to a serialized object. If no match is found, then an InvalidClassException is thrown.

Guidelines for serialVersionUID :

* always include it as a field, for example: "private static final long serialVersionUID = 7526472295622776147L; " include this field even in the first version of the class, as a reminder of its importance
* do not change the value of this field in future versions, unless you are knowingly making changes to the class which will render it incompatible with old serialized objects
* new versions of Serializable classes may or may not be able to read old serialized objects; it depends upon the nature of the change; provide a pointer to Sun's guidelines for what constitutes a compatible change, as a convenience to future maintainers

In Windows, generate serialVersionUID using the JDK's graphical tool like so :

* use Control Panel | System | Environment to set the classpath to the correct directory
* run serialver -show from the command line
* point the tool to the class file including the package, for example, finance.stock.Account - without the .class
* (here are the serialver docs for both Win and Unix)

readObject and writeObject :

* readObject implementations always start by calling default methods
* deserialization must be treated as any constructor : validate the object state at the end of deserializing - this implies that readObject should almost always be implemented in Serializable classes, such that this validation is performed.
* deserialization must be treated as any constructor : if constructors make defensive copies for mutable object fields, so must readObject
* when serializing a Collection, store the number of objects in the Collection as well, and use this number to read them back in upon deserialization; avoid tricks using null

Other points :

* use javadoc's @serial tag to denote Serializable fields
* the .ser extension is conventionally used for files representing serialized objects
* no static or transient fields undergo default serialization
* extendable classes should not be Serializable, unless necessary
* inner classes should rarely, if ever, implement Serializable
* container classes should usually follow the style of Hashtable, which implements Serializable by storing keys and values, as opposed to a large hash table data structure

/**
* Determines if a de-serialized file is compatible with this class.
*
* Maintainers must change this value if and only if the new version
* of this class is not compatible with old versions. See Sun docs
* for * /serialization/spec/version.doc.html> details.
*
* Not necessary to include in first version of the class, but
* included here as a reminder of its importance.
*/
private static final long serialVersionUID = 7526471155622776147L;

[Post New]posted Monday, May 09, 2005 10:44 PM private message
Quote [Up]
*g* as you mention "Java RMI"... it says:

"The downside of using serialVersionUID is that, if a significant change is made (for example, if a field is added to the class definition), the suid will not reflect this difference. This means that the deserialization code might not detect an incompatible version of a class."

and furtheron suggests to implement readObject & friends and writing a version "manually".

All this in order to gain performance:

"Setting serialVersionUID is a simple, and often surprisingly noticeable, performance improvement. If you don't set serialVersionUID, the serialization mechanism has to compute it. This involves going through all the fields and methods and computing a hash. If you set serialVersionUID, on the other hand, the serialization mechanism simply looks up a single value."

Satyam -Latest information

2009-01-09T20:16:00.000-08:00

Mr.Raju surrendered to HYG DGP last night. Experts says that this was a wise movement from Mr.Raju. The main concerns now are

1. How many people from the corporate are involved in the sandal?
2. What about the future of the 53,000 employees?
3. Do the existing customers are willing to continue with satyam projects.?
4. Is Satyam going to pay salaries for the employees for couple of months. Rumors that Satyam does not have enough fund for paying off Salaries for the employees and they might layoff 10,000 employees or cut short the salary for the employees. However there are no official communication from Satyam on this.

Experts says that whatever happens, eventually it is the employees who are going to pay off due to any type of fraud from their bosses. That being a general statement, lets hope it will not happen with Satyam employees.

However personally I support Mr.Raju. I am not very sure about what inside the scandal issue. But from my understanding there are something bigger behind the scene.
Lets wait & see!!!!

2009

2009-01-02T05:49:00.000-08:00

Satyam-India's 4th largest IT company is having tough time in 2009. I hope there will be a positive result after the January 10th borad meeting. Roumers are many other top companies like IBM, HP and CTS are in top list of the bidding companies.

How to use tag with tag for dynamic variables

2008-12-26T16:22:00.000-08:00

I had a specific requirement in my new project. The business functionality is to develop a simple screen with only 2 set of fields. One field with city name and other a drop down which will have list of country name and the default name in the drop down should be the country in which the city is displayed. The catch is the combination of cities are dynamic and the list of countries are static with almost 500 in the list. We can consider the city name & list of countries as a single row in the screen. I mean there will be that many combination of city and drop down country, be there as many products .

Example:

City Name Country Name
-----------------------------------------------------------------
Toronto Canada(this is the default from the list of 500)
London UK(this is the default from the list of 500)
.................etc

For this I have used the following

JSP code
----------------------------------------------------------------------------

-----------------------------------------------------------------------------

in the form there will be 2 arraylists. citiesArrayList and arrayListOfVOs and getter and setter along with the indexed getter for retrieving the countyVO from the arraylist.

I found this very useful because there is not even a single javascript in the code.
Hope this article will be useful for people who are hesitate to use javascript in their code.

How to use tiles ?

2008-11-19T18:04:00.000-08:00

Adding Tiles to Your Application

Here are the steps necessary for adding Tiles to your Struts application:

1. Add the Tiles Tag Library Descriptor (TLD) file to the application.
2. Create layout JSPs.
3. Update existing JSPs to use layouts.
4. Create a tiles-defs.xml file.
5. Update forward definitions in and add the Tiles plug-in to the struts-config.xml file.
6. Repackage and run the updated application.

how to start with struts in your project?

2008-11-19T12:22:00.001-08:00

http://www.java-tips.org/other-api-tips/struts/how-to-use-struts-framework.html

CSS in table

2008-11-19T11:37:00.000-08:00

What does the Table Option Tag td class do

class="xxxx">;>;

Indicates that the table cell can be styled with a CSS rule targeting the ".xxxx" selector.

visit http://www.w3c.org/Style/CSS/

JVMDG217: Dump Handler is Processing a Signal - Please Wait.

2008-11-14T16:15:00.000-08:00

I am getting the following error while starting my application.

JVMDG217: Dump Handler is Processing a Signal - Please Wait.
JVMDG303: JVM Requesting Java core file
JVMDG304: Java core file written to C:\Program Files\IBM\Rational\SDP\6.0\javacore.20081113.172339.652.txt
JVMDG215: Dump Handler has Processed Exception Signal 11.

Trying to resolve the issue. I will post the resolution once I solve the issue.

Travel Tips and Details

2008-11-13T19:30:00.001-08:00

Please visit site http://members.virtualtourist.com/m/ce3e8/

Travel Tips and Details

2008-11-13T19:30:00.000-08:00

Please visit site

Banned products

2008-11-12T08:39:00.001-08:00

Dangerous Shampoo!!!
Banned By Dubai Government!!

Sodium Laureth Sulfate

SLS
CLEAR , FRUCTIS ,
Vo5, Palmolive, Paul Mitchell,L'Oreal, Body Shop

All these Shampoos use a chemical called SLS which is actually a floor cleaner. They are used so as to produce more foam.

Imagine what a floor cleaner can do to you hair and scalp. It will damage the very roots of your scalp.
Check out for SLS in toothpaste too!!!
Use the ones which are free from this extremely harmful chemical.
Type in 'SLS Free Shampoo' or 'SLS Free Toothpaste' in Google.Com to get a list of companies selling safe products

Attention please.....

Don't eat Kurkure because it contains high amount of plastic if U don't believe burn Kurkure n U can see plastic melting. Please forward to all!!!!!!!!!!! Inform all whom you think requires this message as they eat Kurkure.

News report from Times of India
Avoid these tablets they are very dangerous
§ D Cold
§ Vicks Action- 500
§ Actifed
§ Coldarin
§ Cosome
§ Nice
§ Nimulid
§ Cetrizet-D

They contain Phenyl- Propanol -Amide PPA.Which causes strokes, and these tablets are banned by FDA in U..S.

Cotton Ear Buds... (Must read it)

Please do not show sympathy to people selling buds on roadside or at signals.....
Just wanted to warn you people not to buy those packs of ear buds you get at the roadside. It's made from cotton that has already been used in hospitals.
They take all the dirty, blood and pus filled cotton, wash it, bleach it and use it to make ear buds. So, unless you want to become the first person in the world to get Herpes Zoster Oticus (a viral infection of the inner, middle, and external ear) of the ear and that too from a cotton bud, DON'T BUY THEM!

Please forward to all. This may be helpful for someone..........

Satyam layoff again

2008-11-12T08:03:00.000-08:00

India's major IT sector satyam computers laying off more employees. This has been reported by few of my friends in hyderabad. However there has not been any offical information on this. The expected or target number is 10,000.

2008-10-29T13:43:00.000-07:00

viswanathan anand retains the world champion title. The 11th game ended in a draw which took him an unbeaten lead of 6.5-4.5 in the 12 game games. congratulation anand. we all are proud of you.

tennis: Is this end of Roger's Era?

2008-03-22T16:33:00.000-07:00

the world number one again lost! it's disappointing for Federer as well as fans. In pacific open le lost to mardy fisd(6-3,6-2)

ICC's new rules......

2008-01-08T14:33:00.000-08:00

ICC Amendments to the cricket rule book:

(1) Ricky Ponting (THE TRULY GENUINE CRICKETER OF THE CRICKET ERA AND WHOSE INTEGRITY SHOULD NOT BE DOUBTED) should be considered as the FOURTH UMPIRE. As per the new rules, FOURTH UMPIRE decision is final and will override any decisions taken by any other umpires. ON-FIELD umpires can seek the assistance of RICKY PONTING even if he is not on the field.

This rule is to be made, so that every team should understand the importance of the FOURTH UMPIRE.

(2) While AUSTRALIAN TEAM is bowling, If the ball flies anywhere close to the AUSTRALIAN FIELDER(WITHIN 5 metre distance), the batsman is to be considered OUT irrelevant of whether the catch was taken cleanly or grassed. Any decision for further clarification should be seeked from the FOURTH UMPIRE. This is made to ensure that the cricket is played with SPORTIVE SPIRIT by all the teams.

(3) While BATTING, AUSTRALIAN players will wait for the ON-FIELD UMPIRE decisions only (even if the catch goes to the FIFTH SLIP as the ball might not have touched the bat). Each AUSTRALIAN batsman has to be out FOUR TIMES (minimum) before he can return to the pavilion. In case of THE CRICKETER WITH INTEGRITY, this can be higher.

(4) UMPIRES should consider a huge bonus if an AUSTRALIAN player scores a century. Any wrong decisions can be ignored as they will be paid huge bonus and will receive the backing of the AUSTRALIAN team and board.

(5) All AUSTRALIAN players are eligible to keep commenting about all players on the field and the OPPONENT TEAM should never comment as they will be spoiling the spirit of the AUSTRALIAN team. Any comments made in any other language are to be considered as RACISM only.

(6) MATCH REFREE decisions will be taken purely on the AUSTRALIAN TEAM advices only. Player views from the other teams decisions will not be considered for hearing. MATCH REFEREES are to be given huge bonus if this rule is implemented.

(7) NO VISITING TEAM should plan to win in AUSTRALIA. This is to ensure that the sportive spirit of CRICKET is maintained.

(8) THE MOST IMPORTANT RULE: If any bowler gets RICKY PONTING -THE UNDISPUTED CRICKETER WITH INTEGTIRY IN THE GAME OF CRICKET more than twice in a series, he will be banned for the REST OF THE SERIES. This is to ensure that the best batsman/Captain plays uninterrupted to break records and create history in the game of CRICKET.

all surprises

2007-03-28T00:53:00.000-07:00

whats happening with FedExpress !!! Just unbelievable. But from the beginning of Miami he does not look comfortable. may be he was afraid of canas :-)

on the other side Serena did a fabulous job. But I believe Henin would be able to stop her.

Indian Cricket

2007-03-26T13:44:00.000-07:00

may be we were little more predictive about the Indian team. Most of the Indian fans including myself were in dream world of seeing the Blue team in final/semi finals. One way it's good that they crashed out in prilims.

may be they can learn some new lessons from Bangladesh and Srilanka. Hopefully they would do well in 20*20 world cup in september, in Johannasberg, SA.

I am not expecting any more Sachin,Kumble, Dhoni in the team. Wondering how Dhoni is in top 10 list :-), It's shame indeed.

Just a ray of hope

2007-03-21T21:21:00.000-07:00

sorry for being hypothetical.. :-)

Year 1981
1. Prince Charles got married
2. Liverpool crowned Champions of Europe
3. Australia lost the Ashes
4. Pope Died
5. 2 years later India won the world Cup!!!

Year 2005

1. Prince Charles got married
2. Liverpool crowned Champions of Europe
3. Australia lost the Ashes
4. Pope Died
5. 2 years later will India win the world Cup?????

Well deserved win

2007-03-19T14:06:00.000-07:00

India had a convincing win though it was against the beginers Bermuda. Now the scope for India in Super8 is warm. Let's hope for the best & the match against SL is not going to be easy.

All the best team India.

India fighting back !!

2007-03-19T08:24:00.000-07:00

India is fighting back strong in WC 07. There was a threaten in the first over itself from the Bermuda team. It was surprising the way Uttapa got out!

thanks to Ganguly & Sehwag for the blistering start for the first time for India which the 100 crore were expecting.
cheers cheers Blue team :-)

Tennis Sony Ericsson Open- Miami, FL

2007-03-18T21:39:00.000-07:00

It's going to be a wonderful ever as all top seeded players both from men and women are participating in Miami, FL. Roger Federer is going to reign his title while Sharapova will have to prove her supremacy in tennis. She is going to have a tough time from Justin, Mauresmo and Serena.

As per my expectation Federer would lift the championships. The unforgettable defeat at Indian Wells for Roger is not going to repeat until French Open :-)

All my money is for Justin in the women's side. Hopefully she will fight back to retain number 1 place.

for details http://www.sonyericssonopen.com

ICC WC Statistics -India's chances for Super -8

2007-03-18T21:24:00.000-07:00

This is a disastrous starting for India. As a cricket lover, I did not expect this poor performance from the Blue team.

Here are some statistical report for India's chances for the last 8.

1. If India loses at least 1 game of the 2.
1.1. BAN loses both games against Bermuda & SL then NRR will be considered for the 2nd place in group B. SL will be automatically in the Su8.
1.2. If BAN wins against SL & loses against BER then, the match between IND & SL is important. Again NRR comes into picture.

2. If India wins both matches and BAN also wins both matches & SL defeats BER, then BAN will be directly into the Su-8 and NRR is considered among IND & SL.

Here the considering the fact that SL already got a very good NRR, India must defeat BER and SL in big margin.

All the best to Indian team!!

for details http://cricketworldcup.indya.com/