w3hJava

Long back, I had written one blog on how to list Java Process running on System by Java Code. But with the new features of JDK6, you can not only see the list but can manage the other running Java Process. This is possible using class LocalVirtualMachine. This class has a list of methods :

connectorAddress,
displayName,
getAllVirtualMachines,
getLocalVirtualMachine,
isAttachable,
isManageable,
startManagementAgent,
toString,
vmid

Here I am just showing a simple code, which will again tell you all the running Java Process.

import sun.tools.jconsole.*;
import java.util.*;
public class Main {

public static void main(String[] args) {
Map map = LocalVirtualMachine.getAllVirtualMachines();
Iterator iter = map.values().iterator();
LocalVirtualMachine vm = null;
while (iter.hasNext()) {
vm = (LocalVirtualMachine)iter.next();
System.out.println(vm.displayName());
}
}
}

A very very small code :). Note that this class is not in rt.jar so we need to add jconsole.jar and tools.jar in the classpath section.
So, here how you can run this code :

D:Program FilesJavajdk1.6.0_11binControlJavaApp>..javac -cp "D:Program Fi
lesJavajdk1.6.0_11libjconsole.jar" Main.java

D:Program FilesJavajdk1.6.0_11binControlJavaApp>..java -cp .;"D:Program F
ilesJavajdk1.6.0_11libjconsole.jar";"D:Program FilesJavajdk1.6.0_11libt
ools.jar" Main

Right now, in my system it is displaying:

Main
org/netbeans/modules/javafx/preview/Main 1

which mean this code itself and netbeans code.

In next blog, I will try to show how to manage other running java code from a java code.

If liked it, then why not share!

This is a good feature for all those developer who do a lot of file reading, writing stuff. Java SE 6.0 gives us the feature to set file read only. There are lot of place where its correct and valid to set file as read only rather than leaving it read-write. Like you are writing some version repository or some file that should not be changed.

Here is a small code to change the file read mode:

import java.io.File;
import java.io.IOException;

public class FileReadOnly {

public static void main(String[] args) throws IOException {

File file = new File(”test.txt”);

file.createNewFile();
System.out.println(”Before. canWrite?” + file.canWrite());

file.setWritable(false);
System.out.println(”After. canWrite?” + file.canWrite());
}
}

So, from next time don’t forget to use this.

If liked it, then why not share!

Sending mails or messaging from Java is never been a tough process but still most of us has to write Java Messaging API or Java Mail API to do this, which is a cumbersome process in itself.

JDK6 came with a new Desktop class in which you can give user the option to work on the default mail client, do whatever you want to do and after closing the default client the control will go back to the java code. Here is a small code to do that:

import java.awt.Desktop;
import java.io.IOException;
import java.net.URI;

public class DefaultMail {
public static void main(String[] a)throws Exception {
Desktop desktop = null;
if (Desktop.isDesktopSupported()) {
desktop = Desktop.getDesktop();
}

desktop.mail(”mailto”, “vaibhav.choudhary@sun.com”, null);
}
}

The idea is clean I guess, the default client will give more option than Java mail API or anything else. Desktop class give lot more other functionality as well, which we will discuss later.

If liked it, then why not share!

Last Friday, I have given a talk on Java SE 6u10 features in BOJUG meet. Here is the presentation.

These slides basically talks about Java SE 6u10 features. Some of them are cool like

-> Next Generation Plugin where you can drap plugin outside the browser.

-> Kernel JRE. Download small JRE.

-> Nimbus Look And Feel

-> New Applet feature which we talk in prev. blog.

And many more.

Please provide your comment on the presentation.

If liked it, then why not share!

Take care of disk space when you are writing a big program :). Use JDK 6 features:

import java.io.File;

public class DiskSpaceCheck {
public DiskSpaceCheck() {
File file = new File("E:");
System.out.println("E:");
System.out.println("Total:  " + file.getTotalSpace());
System.out.println("Free:   " + file.getFreeSpace());
System.out.println("Usable: " + file.getUsableSpace());

file = new File("E://movie");
System.out.println("E://movie");
System.out.println("Total:  " + file.getTotalSpace());
System.out.println("Free:   " + file.getFreeSpace());
System.out.println("Usable: " + file.getUsableSpace());

file = new File("/");
System.out.println("n/");
System.out.println("Total:  " + file.getTotalSpace());
System.out.println("Free:   " + file.getFreeSpace());
System.out.println("Usable: " + file.getUsableSpace());
}

public static void main(String[] args) {
new DiskSpaceCheck();
}
}

I was actually very suprised that why this feature came so late.

If liked it, then why not share!