Hi..i wanted to develop a whiteboard application..i know the basics of java..but have no idea where to start from..so..i'd really appreciate if you could guide me..as in..where do i start from??
I am new to web development, I have to create a web application in Java using GWT that connects to a database and download a file from it. Regardless of the type of database, what does the web application need in order to create a connection with the database? E.g. an API
Hi,
is there a way to log the JdbcTemplate's DataSource connection URL in Java?
The field exists in the DataSource, but there ain't a getter to access it. Of course I could read the DataSource properties from the application context xml, but I'd like to do it the other way.
I've written the following if-statement in Java:
if(methodName.equals("set" + this.name) ||
isBoolean() ? methodName.equals("is" + this.name) :
methodName.equals("get" + this.name)) {
...
}
Is this a good practice to write such expressions in if, to separate state from condition? And can this expression be simplified?
We have a very strange problem in out application, all of a sudden we started noticing upside down question marks being saved along with other text typed in to the fields on the screen. These upside down question marks were not originally entered by the users and it is unclear where they come from. We are using Oracle 10g with java.
And this is happening, even when no data is copied from Microsoft Word
Hello Guys
i just want to create a simple application that will allow a user to input a url to a rss feed and display the contents to a user.
what would be a good java library to enable me to read rss feeds?
cheers
I have a quadcore processor and I would really like to take advantage of all those cores when I'm running quick simulations. The problem is I'm only familiar with the small Linux cluster we have in the lab and I'm using Vista at home.
What sort of things do I want to look into for multicore programming with C or Java? What is the lingo that I want to google?
Thanks for the help.
I know I can find out if a variable is null in Java using these techniques:
if (var==null) - too much work
try { ... } catch (NullPointerException e) { ...} - it tells me what line is throwing the exception
using the debugger - by hand, too slow
Consider this line of code:
if (this.superSL.items.get(name).getSource().compareTo(VIsualShoppingList.Source_EXTRA)==0) {
I would like to know if there's a generic way to find out programatically what variable (not just the line) is throwing the NullPointerException in a certain area of code. In the example, knowing that
What is the default maximum heap size for Sun's JVM from J2SE 6 (i.e. equivalent to setting -Xmx)?
Looks like for J2SE 5 with a server-class machine, it's
Smaller of 1/4th of the physical memory or 1GB.
Bonus question: Looks like for IBM's JVM you can ask it
java -verbose:sizes -version
Can you similarly ask Sun's JVM?
I heard that using shorts on 32bit system is just more inefficient than using ints. Is this the same for ints on a 64bit system?
Python recently(?) basically merged ints with long and has basically a single datatype long, right? If you are sure that your app. will only run on 64bit then, is it even conceivable (potentially a good idea) to use long for everything in Java?
Is there a way to detect the character encoding set in the terminal which is calling my Java program? In Windows I can call the "chcp" tool and parse the output.
But what about in Linux or Mac?
I have a java main application, and I want to use log4j.
I don't want to hard code my settings, so where do I put the log4j config file so my application can find it?
I'm working on a new Java project and therefore im reading the already existing code. On a very important part of the code if found the following regex expression and i can't really tell what they are doing. Anybody can explain in plain english what they do??
1)
[^,]*|.+(,).+
2)
(\()?\d+(?(1)\))
I want to know if it is possible to send PUT, DELETE request (practically) through java.net.HttpURLConnection to HTTP-based URL. I have read so many articles describing that how to send GET, POST, TRACE, OPTIONS request but still not finding any sample code which successfully perform PUT and DELETE request. Can any one give idea regarding that?
Will incrementing the instance variables of an object ever lead to a stack overflow error?
For example:
This method (java) will cause a stack overflow error:
class StackOverflow {
public static void StackOverflow (int x)
{
System.out.println (x) ;
StackOverflow(x+1) ;
}
public static void main (String[]arg) { StackOverflow (0) ;
}
but will this?: (..... is a gap that i've put in to shorten the code. its long enough as it is.)
import java.util.*;
class Dice
{
String name ;
int x ;
int[] sum ;
....
public Dice (String name)
{
this.name = name ;
this.x = 0 ;
this.sum = new int[7] ;
}
....
public static void main (String[] arg)
{
Dice a1 = new Dice ("a1") ;
for (int i = 0; i<6000000; i++)
{
a1.roll () ;
printDice(a1) ;
}
}
....
public void roll ()
{
this.x = randNum(1, this.sum.length) ;
this.sum[x] ++ ;
}
public static int randNum (int a, int b)
{
Random random = new Random() ;
int c = (b-a) ;
int randomNumber = ((random.nextInt(c)) + a) ;
return randomNumber ;
}
public static void printDice (Dice Dice)
{
System.out.println (Dice.name) ;
System.out.println ("value: "+Dice.x) ;
printValues (Dice) ;
}
public static void printValues (Dice Dice)
{
for (int i = 0; i<Dice.sum.length; i++)
System.out.println ("#of "+i+"'s: "+Dice.sum[i]) ;
}
}
The above doesn't currently cause a stack overflow error but could i get it too if i changed this line in main: for (int i = 0; i<6000000; i++) so that instead of 6 million something sufficiently high were there?
Hi I have host web application which is developed using java and jsp. In client side each client give five ajax calls to the server to retrieve data from the server in every 30 seconds.
My problem is can one user who use one browser to log in to the system have multiple session at a time. Reason is when i use the tool to use monitor the firewall I can see more than 10 sessions are active for one IP. How this can happen? any comments
In Java, how can I construct a Type object for Map<String, String>?
System.out.println(Map<String, String>.class);
doesn't compile. One workaround I can think of is
private Map<String, String> dummy() { throw new Error(); }
Type mapStringString = Class.forName("ThisClass").getMethod("dummy", null).getGenericReturnType();
Is this the correct way?
I saw this video, and I am really curious how it was performed. Does anyone have any ideas? My intuition is that he scraped pixels from the screen (one per 'box'), and then fed that into some program to determine the next move.
Is scraping pixel-by-pixel the way to do this, or is there a better way? I am looking to do something similar with either Java or Python.
Thanks
I have 3 boxes, each box contain 10 piece of numbered paper (1 - 10) but there is a number the same in all 3 boxes eg: box1 has number 4 and box2 has number 4 and box3 also has number 4. How to find that repeated number in java with an efficient/fastest way possible?
Hello everyone! I try to learn java for android devices..
i have to create the update function. But still have one question: How????
in class root
public void update(){
maindebug("update"); // This is my debug function
}
public void run(){
while(isRunning){ // isRunning is a boolean variable
SystemClock.sleep(100);
update();
}
}
and inside onCreate
run();
but it doesnt work :(
I get the following error:
Illegal Argument java/lang/IllegalArgumentException Current Displayable is an Alert
I'm not sure what is means and why this exception is fired.