Java Programming Concepts

Why float type cast

parveen.gupta.23091987 — Tue, 31 Jan 2012 07:10:53 -0500

in java why float we has to be type cast i.e. float a = (float)2.3; and and if 2.3 is consider as double then why there is a need for that ???

Community Discussion

Gotfocus event

sjohnfernandas — Thu, 15 Dec 2011 07:56:52 -0500

when we use shift+tab the controls goes back and select the value in the field
how can we do the same programmically through java swing

Community Discussion

Hibernate query for joining two tables.

lofa in — Mon, 14 Nov 2011 05:40:09 -0500

I need to join two tables User and Employee. And the query will be like,

List list = hibernateTemplate.find("from User u left join fetch u.employee e");

So what I have to do in the User,Employee POJO.
SQL requirement is SELECT userName,firstName from Employee as e LEFT JOIN User as u ON u.userId = e. userId.

Tools and Methods

regarding row reading from Mysql ..

krishna523 — Mon, 14 Nov 2011 01:33:50 -0500

i am trying to read rows from mysql database.like

............
.........
while(rs.next){

x=rs.getstring("columnname");

}

my question is when a row is readed some action is to be perfromed.but in this case control goes to next row before completion of task.

how to handle it ,please help me if anyone aware of it.

Thanks ,
krishna umareddy.

Enterprise Java

How to manage a dbms with multimedia content in java - jdbc(client /server)

arunrajp — Mon, 07 Nov 2011 09:54:46 -0500

I am an old timer from the 90s so java7 is a bit of a shock to me as ima an SCJP for java 2 platform from 2000.

Please suggest the best way to manage a multimedia databse containg (*.jpg and *.au) files in a DBMS or RDBMS using JDBC for both client(Standalone java application) and server side(Servlets).

Enterprise Java

How to remove prefix from target namespace

hemant89 — Thu, 03 Nov 2011 03:28:29 -0400

Hi All,

I am new to this forum.
I am working on java web services. I am using "wsdl2java" tool to create a java stub file.
In my wsdl file value of targetnamespace is "urn:HPD_IncidentInterface_Create_WS" but i want to remove this urn prefix from java stub file.
I can't change wsdl file as it is application generated so is there any way to do this.

Thanks

Tools and Methods

If else if else if else!!!!!

garnaout — Tue, 20 Sep 2011 15:15:44 -0400

I am parsing a string where the number of words is always changing. Since I have a minimum number of 1 word and max of 12 I wrote this function:

private void initializeParts(Scanner scanner) { if ( scanner.hasNext() ) // replace with a function/switch case for a better coding practice { part1 = scanner.next();


			if(scanner.hasNext())

			{

				part2 = scanner.next();

			}

			if(scanner.hasNext())

			{

				part3 = scanner.next();

			}

			if(scanner.hasNext())

			{

				part4 = scanner.next();

			}

			if(scanner.hasNext())

			{

				part5 = scanner.next(); 

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Avoid a cast when using class literals
bonzo101 — Tue, 20 Sep 2011 08:07:13 -0400
Hello. I have a question on java type safety.
I have a method that accepts a class literal and (for sake of argument) returns an instance of any class (in fact there is slightly more to it). 
Example:
Circle c = (Circle)this.returnInstance(Circle.class);

//removed exception handling
private Object returnInstance(Class c) throws Exception {

		return c.newInstance();

	}
My question is - is there any way to avoid performing the CAST (here, on the Circle instance) in the calling code?
Many thanks,

B
Core Java



'TIMER' Rule For Java Coding - Guidelines
hemal.shah — Thu, 15 Sep 2011 04:32:31 -0400
'TIMER' rules for Coding
Poor coding has always been nightmare for the project managers and development managers who are wholly resoponsible for the code delivery and are owners of the same.for many years there has been attempts made to educate the developer to follow the coding standards etc, but practically the coding standards in almost 70% of companies still stand the same. I hereby try to present rules that can be easily remembered by a developer while the person is doing the coding and can eventually check his code before delivery.
T – Testable Code 

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Inheritence problem(a demo form Thing in java)
ljjy23 — Sun, 07 Aug 2011 03:25:04 -0400
while reading Thinking in java, I get confused when I saw the example below(the example is in page 290, Chapter polymorphism):

public class PrivateOverride{
private void f(){print("private f()");}
public static void main(){
PrivateOverride po = new Derived();
po.f();
}
}
class Derived extends PrivateOverride{
public void f(){print("public f()")}
}


the result is private f();

I have two confusions: 

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Core Java



Soft Singleton Idiom
ajitkoti — Wed, 18 May 2011 09:32:07 -0400
There are two ways singletons are created using the Double Check Locking and the Holder Idiom for lazy loading. Both of them create a static singleton object which does not help garbage collection much.

In search of a new way to create singleton without using static object came across this solution which gets rid of creating object in static way and also helps garbage collection as we wrap singleton object with Soft Reference.


package com.singleton;

import java.lang.ref.SoftReference;

import java.util.ArrayList;

import java.util.List; 

Read more ...
Community Discussion



must be done on netbeans6.9...please help me out buddies
Rajesh Khanna — Sun, 15 May 2011 03:36:23 -0400
Design and code a small Object Database System which is to hold a number of Mobile Smart Phone details.
Here is a simple inheritance diagram of the classes and interface required.
The OSInterface is to contain the following: An Array of operating Systems for the phones.
This code is supplied to you as follows:
public interface OSInterface {
     String  [] OSName =  {"Android","ProprietaryOS","AppleIOS4","BradoOS","Windows7","BadaOS","Nokia Series40","SymbianOS"}; 

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Core Java



Oops rules conflict
nandhakumar — Wed, 27 Apr 2011 08:44:28 -0400
The getDeclaredFields() method in the package called java.lang.Class  returns all the declared variables inside a class including private variables. But as per the rule of Oops concept a private variable should not get accessible at the outside of the class.
can any one give a clarification about this.?
Tools and Methods



JavaOne 2011
t3chno — Tue, 19 Apr 2011 03:05:52 -0400
My development team is largely Java based. I am aware of Devoxx and would hope to attend next year, but what are the other conferences that would be useful for my requirements?
Mobile Java



show the selected file and folder in tree structure, with checkbox and the checkbox should be only for root elements not for all
itsanandrhere — Wed, 13 Apr 2011 22:19:33 -0400
Dear all,
By using JFileChoor I am able to select file and folders, Getting JList with File Objects and I am showing it with checkbox. Now my requirement is like I want to show the selected file and folder in tree structure, with checkbox and the checkbox should be only for root elements not for all child elements. Please help me as soon as possible, for me its very urgent.
Like if I selected folders ABC and PQR and file XYZ which containt sub folders and few files

now on UI It should be display 
Checkbox1 ABC--

--SubFolders

. --SubFolder

. --Files

--Files

Checkbox2 PQR-- 

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Core Java



how to print the attributes of an object
tesseract — Tue, 12 Apr 2011 21:38:36 -0400
i have a class by the name Veggie which extends Pizza; similarly, i have another subclass: supreme.  these are two different types of pizza.  
my constructor for Veggie declares an array such that the arguments specified by the constructor take the value of each particular element at the array.  for example:
  Veggie (String size)

  {

     String veg [] = new String [1];

     veg [0] = size;
   } 

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Community Discussion



QCon or Javaone ????
lisaantony06 — Thu, 24 Mar 2011 05:04:55 -0400
My company allows me to visit one international work related (I'm Java/JEE Developer/Technical Lead interested in polyglot programming) conference each year. I've visited Javapolis (devox) in the past.

For this year I'm looking for a conference which is less technology but a bit more methodology focussed... possible like Oracle Develop or QCon or Javaone What would you recommend?
Tools and Methods



How can java record sound sent by other app
jiangyichun — Mon, 14 Mar 2011 03:09:26 -0400
How can I use java to write an application which can record sound sent from the other applications, such as real player, windows media etc.?

I know there is a software named "Total Recorder" can do this, but this software is not free.

I just want a free or open source solution for this. Or is there a free com component which I can use?

I know there is JMF in java, but seems it does not work for this.
Community Discussion



help for developing mobile banking applcation in j2me
nehapurswani — Thu, 24 Feb 2011 13:20:23 -0500
i m creating a mobile banking application in java . i m using j2me wireless messaging technique. can any 1 help me with the code for port number and address
Mobile Java



Does garbage collection occurs in PERM Area of Java Heap ?
javabuddy — Fri, 21 Jan 2011 22:43:22 -0500
Hi Guys,
I am a relative new member in this forum , My name is Javin Paul and I am Java programmer. I have question related to garbage collection in Java 
Does garbage collection occurs in PERM Area of Java Heap ?
As per my knowledge PERM area is used to store meta data about classes, methods , variable etc also String Pool created in PERM area of heap so I believe  garbage collection does not occur in this place but just wanted to know what do you guys think of it ?
Thanks

Javin
Core Java



Tomorrow’s Tech Today: HTML 5 by Scott Davis at GIDS 2011
sapna123 — Mon, 17 Jan 2011 05:45:42 -0500
As software engineers, we take comfort in the idea of concrete specifications. As web developers, our hearts are either broken (frequently!), or we recognize the W3C's role is a delicate balance of leading the browser developers in new and exciting directions while, in their own words, "paving over the cow paths" of existing, de facto standards. Scott Davis is coming back this summer to the fourth season of India's biggest summit for the software developer ecosystem - Great Indian Developer Summit to talk on HTML 5 and its features. 

Read more ...
Core Java



BASIC HELP WITH ARGUMENTS NEEDED
KKuykenda11 — Thu, 23 Dec 2010 19:40:10 -0500
So I swear I typed this in EXACTLY as the book told me but it still says I have an error at the "thread main".  Please help!
class BlankFiller {

    public static void main(String[] args) {

        System.out.println("The " + args[0]

                + " " + args[1] + " fox "

                + "jumped over the "

                + args[2] + " dog."

                );

    }

}
Community Discussion



How to change arraylist to be thread safe?
Shinoy — Mon, 15 Nov 2010 09:15:20 -0500
Hi,
   I have  an application which was single threaded  and so used ArralyList through out the application.Now We want to make that thread safe because application changed to multi threaded.Which is the best way to do that? I don't like to replace with Vector where ever we used ArralyList.
Thanks
Enterprise Java



fields with final keywords can be reassigned..?
kk1687 — Mon, 27 Sep 2010 08:30:35 -0400
Hi folks,

I have a question regarding the final modifier.
We all know the System class has the out, err, in static & final objects defined.
We can get the (out, err, in) Stream objects redirected any other using the System.setOut(), setErr() and setIn method and I could see the objects are getting changed once we do invoke these System.setXXX()methods.

                         Is it contradictory to what we have seen with the key word final.

  I could see the Native implementations for the System.setXXX methods, in the JAVA src code. 

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Core Java



Threads in transaction
zzzxxx — Fri, 03 Sep 2010 05:08:20 -0400
Consider this as a scenario from a java application:
I have 2 threads T1 and T2.
Thread T1 retreives a record from database . (Raw1)

edited Raw1--- call it as T1Updated_Data
Thread T2 retreives the same  record from database .(Raw1)

 edited Raw1--- call it as T2Updated_Data

T2 commits  the record (T2Updated_Data) .
After that T1 commits the record(T1Updated_Data) .
What will happen at this time? transaction commit or not?
Database is Oracle.
Core Java