JDK6u12 - Mixing heavy and lightweight component

So, if you are a Swing Developer, you have heard many stories where someone messed up Lightweight component with Heavyweight component. In one line " A heavyweight component
is one that is associated with its own native screen resource (commonly
known as a peer). A lightweight component is one that "borrows" the
screen resource of an ancestor (which means it has no native resource
of its own -- so it's "lighter")." AWT is all heavyweight, Swing is all lightweight except top level ones like JFrame, JWindow...

Now many times you have heard "Don't mix lightweight and heavyweight". What will happen ? Alright, here is a small code :

 
import javax.swing.*;
import java.awt.*;

public class Test extends JPanel {

  public Test() {
     JComboBox jc = new JComboBox();
     JButton btn1 = new JButton("Button1");
     Button btn2 = new Button("Button2");
     Button btn3 = new Button("Button3");
     jc.addItem("France");
     jc.addItem("Germany");
     jc.addItem("Italy");
     jc.addItem("Japan");

    add(jc);
    add(btn1);
    add(btn2);
    add(btn3);
  }

  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.getContentPane().add(new Test());
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(200, 200);
    frame.setVisible(true);
  }
}

Here what you see the output:

Now, this is what it happen what you mix lightweight and heavyweight. No way, you can bring the drop down items on top of Button2 !!

All Past :) , JDK6 update 12 and JDK7 build 19, the output will be like this:

New JDK release fixed all these problem of mixing lightweight component and heavyweight component. So, don't worry, keep messing :).

For more detail, please see this : http://java.sun.com/developer/technicalArticles/GUI/mixing_components/index.html

For more: Please join us at Tech Days at Hyderabad on 24-25th of March.

LiveConnect Docs for JDK6

JDK6 has done lot of changes in LiveConnect. LiveConnect is a feature in the browser for communication between Java Applet and JavaScript. With the new Plugin2, most of the work has been left on browser to do. Initially it was Java which do a good amount of work. So, now the Java Plug-in will operate like any other scriptable Plug-in.

This is one of the great document written : http://java.sun.com/javase/6/webnotes/6u10/plugin2/liveconnect/

If you want to see some code help, visit: http://java2s.com/Code/Java/JDK-6/Script-Engines.htm

Have Fun !!

JDK6 comparing with JDK1.4.2

Again a comparison and reason why JDK6. Weeks back one of our team member gave a presentation on JVM performance improvement in Mustang. I have just collected a useful point here and try to compare with older JDK version. Here is the code:

import java.util.*;

public class RuntimePerformanceGC {

public static void main(String[] args) {
RuntimePerformanceGC ob = new RuntimePerformanceGC();
Vector v = new Vector();
java.util.Date now = new java.util.Date();
long t1 = now.getTime();
ob.addItems(v);
java.util.Date now1 = new java.util.Date();
System.out.println(now1.getTime()-t1);
}
public void addItems(Vector v) {
for(int i =0;i<500000;i++)
v.add("Item" + i);
}
}

And the output in ms is:

JDK1.4.2: 984

JDK 6: 578

You can see a massive difference. 37 percent improvement in time. Why ? Here goes :

This is because of Runtime Performance Optimization. The new lock coarsening optimization technique implemented in hotspot eliminates the unlock and relock operations when a lock is released and then reacquired with no meaningful work done in between those operations. And this is what happening in our example. Since, Vector do thread safe operation, it takes the lock for add, release the lock and then takes it again.

So, I just tried to give one more reason why use JDK6 ;-). This is off course not the only reason for big improvement, I will try to cover some more in upcoming blogs :-)

Performance Improvement in JDK6

Original Post: http://blogs.sun.com/vaibhav/entry/why_jdk6_again

Content:

Again a comparison and reason why JDK6. Weeks back one of our team member gave a presentation on JVM performance improvement in Mustang. I have just collected a useful point here and try to compare with older JDK version. Here is the code:

import java.util.*;
public class RuntimePerformanceGC {
public static void main(String[] args) {
RuntimePerformanceGC ob = new RuntimePerformanceGC();
Vector v = new Vector();
java.util.Date now = new java.util.Date();
long t1 = now.getTime();
ob.addItems(v);
java.util.Date now1 = new java.util.Date();
System.out.println(now1.getTime()-t1);
}
public void addItems(Vector v) {
for(int i =0;i<500000;i++)
v.add("Item" + i);
}
}

And the output in ms is:

JDK1.4.2: 984

JDK 6: 578

You can see a massive difference. 37 percent improvement in time. Why ? Here goes :

This is because of Runtime Performance Optimization. The new lock coarsening optimization technique implemented in hotspot eliminates the unlock and relock operations when a lock is released and then reacquired with no meaningful work done in between those operations. And this is what happening in our example. Since, Vector do thread safe operation, it takes the lock for add, release the lock and then takes it again.

So, I just tried to give one more reason why use JDK6 ;-). This is off course not the only reason for big improvement, I will try to cover some more in upcoming blogs :-)

Disk Space Check

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.

Nimbus Look And Feel !

Good news for all the user, using JDK6. Though I am little late in writing blog on this but its OK ;). JDK6 current update comes with a new L&F(Look And Feel) called Nimbus.

Nimbus provide more lively look and feel in Swing UI. Here are some examples:

Default Look And Feel(Click to see enlarged mode)
Nimbus Look And Feel((Click to see enlarged mode)

Since the image is little small and related to my Online Java Project(which I can't change), so I provide another example here from my last blog code.

Default Look And Feel
Nimbus Look And Feel
Something more interesting is focus traversal on components. For Default L&F, you can see that there is a dotted rectangle on Button 3, which says "Focus is here" whereas in Nimbus you can see Button 1 with little bluish highlight which says "Look at my focus" :)

Quickest way to try, command line:

Run my previous (or any UI code) with the following option:

java -Dswing.defaultlaf=com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel LayoutCheck

Off course, you can do it with code :

UIManager.setLookAndFeel(
    "com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");

Use try, catch and respect Exception handling as well.