I am facing a problem with my singleton when used across multiple class loaders. E.g Singleton accessed by multiple EJBs. Is there any way to create a singleton which has only one instance across all class loader?
I am looking for pure java solution either using custom class loader or some other way.
Is there a way in Java to find the "Last Fired Time" from a Cron Expression.
E.g. If now = 25-Apr-2010 10pm, cron expression "0 15 10 ? * *" (quartz) should return me 25-Apr-2010 10:15am
I do not care if we use standard cron expressions (like Unix and Quartz) or less popular ones if they can fetch me the correct "Last Fired Time"
Does anyone know of a tool (besides Eclipse or any other IDE) that I can use to find unused imports in a Java source file?
I am looking for a command-line type of tool (to integrate in a larger script).
Thank you.
How to/What is a good library, to create a fading indicator message in Java like that of Outlook when you get a message, or Ubuntu/Gnome when you've connected to a network?
Hi i'm working in task queue concept.... First i struggled to program using task queue and i asked many doubts in stack overflow and Google app engine java. After a search i got a sample program for task queue. http://gaejexperiments.wordpress.com/2009/11/24/episode-10-using-the-task-queue-service/ It will very useful for beginners Like me.
Regards,
Sharun.
Hi there,
is it possible to access a shadowed field of an enclosing class from the enclosed one in Java?
public class Inherit {
public int a = 3;
private int b = 5;
public class Inheriting {
public int a = 23;
private int d = 8;
public void f() {
System.out.println("Here I want to get a = 3");
...
}
}
}
Cheers!
I want to make a java application software which give the current status/information of the running computer. So, for this, is there any inbuilt/extrnal library present or not?
Can anyone give a simple code which will just. "What is the current status of laptop battery?" or "Is AC adapter is pluged in or not?"
Please help me.
Hi,
After some serious googleing I found out that the RandomAccessFile-class is not thread-safe. Now I could use one semaphore to lock all reads and writes but I don't think that performs very well. In theory it should be possible to do multiple reads and one write at a time.
How can I do this in Java? Is it possible at all?
Thanks!
Hi,
I would like to know if its possible to deploy java class files without restarting JBoss server. I am using jboss v4.2.2.
Also, when I try to deploy jsp files, it works fine and server picks up the changes almost instantly.
Thanks a lot in advance :)
What's the easiest way to create a simple HTTP server with Java? Are there any libraries in commons to facilitate this? I only need to respond to GET/POST, and I can't use an application server.
What's the easiest way to accomplish this?
I want to make Java JDialog appear like it is presented in the [Image][1]
[1]: http://lh4.ggpht.com/_AnzmYq61hHI/S8RTAznktKI/AAAAAAAAAW0/c4HVCuchdjc/s1600-h/saveConfiguration%5B2%5D.jpg using JDK 6 Swing. Is it possible? if so kindly guide me.
Image Link
I haven't found many ways to increase the performance of a Java application that does intensive XML processing other than to leverage hardware such as Tarari or Datapower. Does anyone know of any open source ways to accelerate XML parsing?
Hi,
I'm a beginner in java. I want the logic of the small program.
I have two arrays
array = {a1,a2,a3,a4,a5,,,,,,,,,an}
and
array2 = {b1,b2,b3,b4,,,,,,,,,,,bn}
I want string as:
a1b1,a2a3b2b3,a4a5a6b4b5b6,..........an
Please tell me what will be the logic.
What is the best procedure for storing and retrieving, using native Java serialization, generic objects like ArrayList<String>?
Edit: To clarify. When I serialize an object of type ArrayList<String> I'd like to de-serialize to the same type of object. However, I know of no way to cast back to this generic object without causing warnings.
Any tips or best practices for unit testing Google Wave robots written in Java? I'm expecting to deploy on AppEngine, if that helps. I'm a fan of TDD but new to both Wave Robots and AppEngine, so I'm hoping to use TDD to help me explore the design space.
Basically I want to be able to encrypt and decrypt with AES 256. What is the industry standard library for encryption in Java? Something that has been around a long time and is tried and true.
I know in Jython you can do
import java.util.Random as Random
Random().nextInt()
But if I have a class I wrote myself, how can I import it into Jython without putting the class itself in a package? If I have a testclass Test:
public class Test {
public void foo() {
System.out.println("bar");
}
}
that's not inside a package. Can I even import that into jython by using something along the lines offrom Test import Test?
This is simply for fun. This will not be used for any actual encryption. I'm only first year comp sci student and love cryptography.
This took a long time to get working. At approximately N = 18, it begins breaking down. It won't encrypt messages properly after that point. I'm not sure why. Any insights? I'd also appreciate any links you could provide me to tutorials or interesting reading about Cryptography.
import java.math.BigInteger;
import java.security.SecureRandom;
/**
* Cryptography.
*
* Generates public and private keys used in encryption and
* decryption
*
*/
public class RSA
{
private final static BigInteger one = new BigInteger("1");
private final static SecureRandom random = new SecureRandom();
// prime numbers
private BigInteger p;
private BigInteger q;
// modulus
private BigInteger n;
// totient
private BigInteger t;
// public key
private BigInteger e;
// private key
private BigInteger d;
private String cipherText;
/**
* Constructor for objects of class RSA
*/
public RSA(int N)
{
p = BigInteger.probablePrime(N/2, random);
q = BigInteger.probablePrime(N/2, random);
// initialising modulus
n = p.multiply(q);
// initialising t by euclid's totient function (p-1)(q-1)
t = (p.subtract(one)).multiply(q.subtract(one));
// initialising public key ~ 65537 is common public key
e = new BigInteger("65537");
}
public int generatePrivateKey()
{
d = e.modInverse(t);
return d.intValue();
}
public String encrypt(String plainText)
{
String encrypted = "";
int j = 0;
for(int i = 0; i < plainText.length(); i++){
char m = plainText.charAt(i);
BigInteger bi1 = BigInteger.valueOf(m);
BigInteger bi2 = bi1.modPow(e, n);
j = bi2.intValue();
m = (char) j;
encrypted += m;
}
cipherText = encrypted;
return encrypted;
}
public String decrypt()
{
String decrypted = "";
int j = 0;
for(int i = 0; i < cipherText.length(); i++){
char c = cipherText.charAt(i);
BigInteger bi1 = BigInteger.valueOf(c);
BigInteger bi2 = bi1.modPow(d, n);
j = bi2.intValue();
c = (char) j;
decrypted += c;
}
return decrypted;
}
}
I'm using a MySQL database and accessing it through Java.
PreparedStatement prep1 = this.connection.prepareStatement("UPDATE user_table
SET Level = 'Super'
WHERE Username = ?");
prep1.setString(1, username);
The update statement above works fine however I'd like to get the number of rows affected with this statement. Is this possible please?
I have Java Applet(J2EE), I want to make it accessible only to a certain set of users,by authenticating them using username and password.What is the the best way of doing this?