Zone 817

Close Button in the caption bar of a GWT DialogBox

2010-08-29T20:27:00.000-07:00

The following code demonstrates how a 'close button' can be placed in the caption bar of a DialogBox . Note that the example uses a HTML object as the close button , it can be replaced by an Image to make it more eye-candy.

/**
 *PUBLIC SOFTWARE
 *
 *This source code has been placed in the public domain. You can use, modify, and distribute
 *the source code and executable programs based on the source code.
 *
 *However, note the following:
 *
 *DISCLAIMER OF WARRANTY
 *
 * This source code is provided "as is" and without warranties as to performance
 * or merchantability. The author and/or distributors of this source code may
 * have made statements about this source code. Any such statements do not constitute
 * warranties and shall not be relied on by the user in deciding whether to use
 * this source code.This source code is provided without any express or implied
 * warranties whatsoever. Because of the diversity of conditions and hardware
 * under which this source code may be used, no warranty of fitness for a
 * particular purpose is offered. The user is advised to test the source code
 * thoroughly before relying on it. The user must assume the entire risk of
 * using the source code.
 * 
 */

import com.google.gwt.user.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Event.NativePreviewEvent;
import com.google.gwt.user.client.ui.DialogBox;
import com.google.gwt.user.client.ui.HTML;
import com.google.gwt.user.client.ui.HorizontalPanel;

/**
 * @author amal
 * @version 1.0
 */
public class MyDialog extends DialogBox
  {

    HTML close = new HTML("[X]");
    HTML title =new HTML("");
    HorizontalPanel captionPanel = new HorizontalPanel();

    public MyDialog(boolean autoHide, boolean modal)
      {
        super(autoHide, modal);
        Element td = getCellElement(0, 1);
        DOM.removeChild(td, (Element) td.getFirstChildElement());
        DOM.appendChild(td, captionPanel.getElement());
        captionPanel.setStyleName("Caption");//width-100%
        captionPanel.add(title);
        close.addStyleName("CloseButton");//float:right
        captionPanel.add(close);
        super.setGlassEnabled(true);
        super.setAnimationEnabled(true);
      }
    public MyDialog(boolean autoHide)
      {
        this(autoHide, true);
      }
    public MyDialog()
      {
        this(false);
      }

     @Override
    public String getHTML()
      {
        return this.title.getHTML();
      }

    @Override
    public String getText()
      {
        return this.title.getText();
      }

    @Override
    public void setHTML(String html)
      {
        this.title.setHTML(html);
      }

    @Override
    public void setText(String text)
      {
        this.title.setText(text);
      }

    @Override
    protected void onPreviewNativeEvent(NativePreviewEvent event)
      {
        NativeEvent nativeEvent = event.getNativeEvent();

        if (!event.isCanceled()
          && (event.getTypeInt() == Event.ONCLICK)
          && isCloseEvent(nativeEvent))
          {
            this.hide();
          }
        super.onPreviewNativeEvent(event);
      }

    private boolean isCloseEvent(NativeEvent event)
      {
        return event.getEventTarget().equals(close.getElement());//compares equality of the underlying DOM elements
      }
  }

Closing a GWT DialogBox on 'Esc' keypress

2010-08-29T20:00:00.000-07:00

To have a DialogBox do something on a keyboard event , its onPreviewNativeEvent should be overridden . A DialogBox can be made to hide itself on the 'Esc' key event by overriding it's OnPreviewNativeEvent method as follows

@Override
      protected void onPreviewNativeEvent(NativePreviewEvent event)
      {
         if (!event.isCanceled() && 
             event.getTypeInt() == Event.ONKEYDOWN && 
             event.getNativeEvent().getKeyCode() == KeyCodes.KEY_ESCAPE)
        {
             this.hide();
        }
       super.onPreviewNativeEvent(event);
     }

Serializing and De-serializing a Java object to XML

2010-08-29T19:48:00.000-07:00

A Java object can be serialized as XML using the XMLEncoder

try 
{
    XMLEncoder enc= new XMLEncoder(new BufferedOutputStream(
        new FileOutputStream("<output xml file>")));
    enc.writeObject(instance);//instance is the bean object to be serialized
    enc.close();
} 
catch (FileNotFoundException e) 
{
}

De-serializing the XML file can be done as follows using the XMLDecoder

try
 {
    XMLDecoder dec= new XMLDecoder(new BufferedInputStream(
        new FileInputStream("<input xml file>")));
    MyClass o = (MyClass)dec.readObject();
    dec.close();
 } 
catch (FileNotFoundException e)
 {
 }

Loading a class using the URLClassLoader

2010-08-19T06:58:00.000-07:00

The URLClassLoader can be used dynamically load classes from a directory , not necessarily on the classpath. The following code demonstrates how

File file = new File("<directory path>");
try 
{
    URL url = file.toURL();    
    ClassLoader loader= new URLClassLoader(new URL[]{url});
    Class class= loader.loadClass("<class name>");
} 
catch (MalformedURLException e) 
{
}
 catch (ClassNotFoundException e)
{
 }

Javascript equality(==) and identity(===) operators

2010-08-19T06:50:00.000-07:00

The identity operator(===) compares the type and value of the operands , while the equality operator(==) compares just the values .

So , given var i=1

i=='1' will return true , while i==='1' will return false .

Quote from Javascript : The good parts

JavaScript has two sets of equality operators: === and !==, and their evil twins == and !=. The good ones work the way you would expect. If the two operands are of the same type and have the same value, then === produces true and !== produces false. The evil twins do the right thing when the operands are of the same type, but if they are of different types, they attempt to coerce the values. the rules by which they do that are complicated and unmemorable.
My advice is to never use the evil twins. Instead, always use === and !==.

Using readResolve method to create a Serializable Singleton

2010-08-19T06:42:00.000-07:00

The readResolve method allows a class to replace/resolve the object read from the stream before it is returned to the caller. The following code demonstrates how to create a serializable singleton , using the method.

public class Singleton implements Serializable
{
 static Singleton instance= new Singleton ();

private Singleton ()
 {
 }

protected Object readResolve() 
 {
  return instance;
 }

}

Integer constant pool

2010-08-19T06:32:00.000-07:00

Java uses a caching mechanism for Integer , similar to the String Pool . It caches the Integer values from -128 to 127 , meaning '==' comparisons for values in this range returns true .

Integer a=127;
Integer b=127;
System.out.println(a==b);//prints true
a=128;
b=128;
System.out.println(a==b);//prints false

Creating and Firing events with GWT

2010-08-17T06:36:00.000-07:00

The following code demonstrates how to programmatically create an event using GWT.

Document doc=Document.get();
NativeEvent clickEvent=doc.createClickEvent(0, 0,0, 0,0, false, false, false,false);
NativeEvent changeEvent=doc.createChangeEvent();
NativeEvent keyDownEvent=doc.createKeyDownEvent(false, false, false,false,KeyCodes.KEY_ENTER);

.........

The events created can be programmatically fired using the DomEvent.fireNativeEvent method .

Invoking a method by name using Reflection

2010-08-11T02:41:00.000-07:00

It is possible to use reflection to invoke a method using its name , which is known only at runtime . The following code demonstrates the usage of the invoke method . Note that reflection may be used to override the java access checks , allowing the caller to invoke methods that are declared private .

/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/

import java.lang.reflect.*;

/**
*
* @author amal
* version 1.0
*/
public class InvokeTest
{


public static void main(String[] args) throws Exception
{
Class c = Class.forName("X");
Object instance = c.newInstance();
Method m = c.getDeclaredMethod("A",new Class[]{});
m.invoke(instance, new Object[]{});
m = c.getDeclaredMethod("A",new Class[]{int.class});//or INTEGER.TYPE
         m.invoke(instance, new Object[]{1});
m = c.getDeclaredMethod("A",new Class[]{String.class});
m.invoke(instance, new Object[]{"arg"});
m = c.getDeclaredMethod("A",new Class[]{String.class,String.class});
m.setAccessible(true);//supress the java access check
         m.invoke(instance, new Object[]{"arg1","arg2"});

}


}
class X
{
void A()
{
System.out.println("In method A , with no arguments");
}
void A(int i)
{
System.out.println("In method A , with an integer argument "+i);
}
void A(String s)
{
System.out.println("In method A , with a string argument "+s);
}
private void A(String s,String t)
{
System.out.println("In the private method A , with two string arguments "+s+" , "+t);
}
}

Simple Profanity Filter

2010-08-07T03:28:00.000-07:00

A simple Java program demonstrating the use of CDYNE's FREE Profanity Filter API . Note that the code just demonstrates the setting up of a simple profanity filter , the API includes much more functionalities . Check out the CDYNE Wiki for how to implement a profanity filter suited to your needs .

/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/
import java.io.*;
import java.net.*;
/**
*
* @author amal
* version 1.0
*/
public class CDYNEFilterDemo {

public static void main(String[] args)
{
BufferedReader in = null;
try
{
String text = "test profanity bullshit";
URL url = new URL("http://ws.cdyne.com/ProfanityWS/Profanity.asmx/SimpleProfanityFilter?Text="+URLEncoder.encode(text,"UTF-8"));
in = new BufferedReader(new InputStreamReader(url.openStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
{
System.out.println(inputLine);
}
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
if (null != in)
{
in.close();
}
}
catch (IOException e)
{
// ignore
              }
}
}
}

Strings in Java - Immutablility , Interning and the String pool

2010-08-03T09:40:00.000-07:00

Immutability

Strings in Java are immutable .An immutable object is one whose state cannot be modified once it is created . In Java , Strings are immutable . An interesting side-effect of the immutability of Strings is that methods like toLowerCase() in the String class doesn't affect the state of the original String , rather returns a new String.

Interning & The String pool

String interning is a method of storing only one copy of each distinct string value, which must be immutable. Interning strings makes some string processing tasks more time- or space-efficient at the cost of requiring more time when the string is created or interned. In Java , strings are interned using a String literal pool .

Each time your code create a string literal, the JVM checks the string literal pool first. If the string already exists in the pool, a reference to the pooled instance returns. If the string does not exist in the pool, a new String object is created and placed in the pool. Java can make this optimization since strings are immutable and can be shared without fear of data corruption.

A side-effect of String interning in Java can be demonstrated by this code snippet.

String s1="aaaaa";
String s2="aaaaa";
System.out.println(s1==s2);

The above code snippet prints true because the two Strings are interned , and refers to the same pool instance.

Literal Strings , including those that can be computed by constant expressions at compile time are interned .

Strings explicitly created by the constructor or by concatenation at runtime are not interned.

The intern() method

The docs state When the intern method is invoked, if the pool already contains a

string equal to the String\ object as determined by

the method, then the string from the pool is

returned. Otherwise, the String object is added to the

pool and a reference to the String object is returned.

The below code snippet demonstrates the behaviour of the intern() method.

String s1 = "Zone817";
String s2 = new StringBuffer("Zone").append("817").toString();
String s3 = s2.intern();
System.out.println(s1 == s2);//prints false
System.out.println(s1 == s3);//prints true

Mimicking a browser user-agent in a request

2010-08-02T08:47:00.000-07:00

The following code demonstrates how to 'forge' the user-agent string in a request , making the request seem like it originated from a browser.



/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/
import java.io.*;
import java.net.*;
/**
*
* @author amal
* version 1.0
*/



public class UrlConB
{

public static void main(String[] args)
{
InputStreamReader in = null;
try
{
String query = "web";
Socket s = new Socket("bing.com", 80);
PrintStream p = new PrintStream(s.getOutputStream());
p.print("GET /search?q=" + query + " HTTP/1.0\r\n");
p.print("User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/533.2 (KHTML, like Gecko) Chrome/6.0\r\n");
p.print("Connection: close\r\n\r\n");
in = new InputStreamReader(s.getInputStream());
BufferedReader buffer = new BufferedReader(in);
String line;
while ((line = buffer.readLine()) != null)
{
System.out.println(line);
}
in.close();
}
catch (UnknownHostException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
if (null != in)
in.close();
}
catch (IOException e)
{
// ignore
              }
}
}
}

Connecting to an Url using a Java program - Connecting through a proxy

2010-08-02T08:27:00.000-07:00

The following code demonstartes how to connect to an url through a proxy . The code uses the default system proxy.

In case you want to use a different proxy than the default system proxy , you need to set the http.proxyHost and http.proxyPort

properties from your code using setProperty method of the System class ,

or you can provide the values as command line arguments when starting your java program , like

java -Dhttp.proxyHost=hostname -Dhttp.proxyPort=portNumber foo

, where foo is the name of the class . You may also create an instance of the Proxy class ,

and pass it to the openConnection() method of the URL class.

/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/
import java.io.*;
import java.net.*;
import com.sun.org.apache.xml.internal.security.utils.Base64;

/**
*
* @author amal
* version 1.0
*/



public class UrlConA
{

public static void main(String[] args)
{
System.setProperty("java.net.useSystemProxies", "true");
BufferedReader in = null;
try
{
URL url = new URL("http://www.w3schools.com");
URLConnection uc = url.openConnection();
String encoded = new String(Base64.encode(new String(
"username:password").getBytes()));
uc.setRequestProperty("Proxy-Authorization", "Basic " + encoded);
uc.connect();
in = new BufferedReader(new InputStreamReader(uc.getInputStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
{
System.out.println(inputLine);
}
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
if (null != in)
{
in.close();
}
}
catch (IOException e)
{
// ignore
              }
}
}
}

Connecting to an Url using a Java program

2010-08-02T08:25:00.000-07:00

The following code demonstrates how to read from a url using java.

/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/
import java.io.*;
import java.net.*;

/**
*
* @author amal
* version 1.0
*/



public class UrlCon
{

public static void main(String[] args)
{
BufferedReader in = null;
try
{
URL url = new URL("http://www.bing.com/");
in = new BufferedReader(new InputStreamReader(url.openStream()));
String inputLine;
while ((inputLine = in.readLine()) != null)
{
System.out.println(inputLine);
}
}
catch (MalformedURLException e)
{
e.printStackTrace();
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
try
{
if (null != in)
{
in.close();
}
}
catch (IOException e)
{
// ignore
              }
}
}
}

Example code for sending mail with attachments using Java

2010-08-01T07:22:00.000-07:00

The following code demonstrates how to send a mail with JavaMail . The example code uses the mail.jar file , which is included in the JavaMail download .



/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/

import java.util.*;
import javax.activation.*;
import javax.mail.*;
import javax.mail.internet.*;

/**
*
* @author amal
* version 1.0
*/
public class Mailer {
public static void main(String[] args) throws Exception{
Properties properties = new Properties();
properties.setProperty("mail.transport.protocol", "smtp");
properties.setProperty("mail.host", "mailServer");
properties.setProperty("mail.user", "emailUser");
properties.setProperty("mail.password", "emailPassword");
Session sess = Session.getDefaultInstance(properties, null);
Transport transport = sess.getTransport();
MimeMessage message = new MimeMessage(sess);
message.setSubject("Mail Subject");
MimeBodyPart textPart = new MimeBodyPart();
textPart.setContent("Mail Content", "text/html");
MimeBodyPart attachmentPart = new MimeBodyPart();
FileDataSource fileDS =new FileDataSource("FileToBeAttached");
attachmentPart.setDataHandler(new DataHandler(fileDS));
attachmentPart.setFileName(fileDS.getName());
Multipart multipart = new MimeMultipart();
multipart.addBodyPart(textPart);
multipart.addBodyPart(attachmentPart);
message.setContent(multipart);
message.addRecipient(Message.RecipientType.TO,
new InternetAddress("recepient@domain.com"));
transport.connect();
transport.sendMessage(message,
message.getRecipients(Message.RecipientType.TO));
transport.close();
}
}

Comparing BigDecimals using equals

2010-07-31T11:50:00.000-07:00

One important thing to know when you are comparing BigDecimals in Java is that the equals method returns true only if the objects being compared are equal in value and scale . So 3.14 not equals 3.140 if you are using the equals method .

Alternatives that can be used .

The compareTo method in BigDecimal is the obvious alternative to overcome the issue mentioned above . Another way would be to use the stripTrailingZeros methods on both objects before comparing them with equals .

However ,the stripTrailingZeros method does create a new object , and so might have

an performance overhead .

    BigDecimal d1=new BigDecimal("3.14");
BigDecimal d2=new BigDecimal("3.140");
System.out.println(d1.equals(d2));
System.out.println(d1.compareTo(d2)==0);
System.out.println(d1.stripTrailingZeros().equals(d2.stripTrailingZeros()));

Customizing a SuggestBox to simulate a Selection Box.

2010-07-28T11:02:00.000-07:00

This class attempts to combine the features of a SuggestBox and a ListBox .


/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/

import com.google.gwt.event.dom.client.ChangeEvent;
import com.google.gwt.event.dom.client.ChangeHandler;
import com.google.gwt.event.dom.client.KeyUpEvent;
import com.google.gwt.event.dom.client.KeyUpHandler;
import com.google.gwt.event.logical.shared.SelectionEvent;
import com.google.gwt.event.logical.shared.SelectionHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.user.client.ui.MultiWordSuggestOracle;
import com.google.gwt.user.client.ui.SuggestBox;
import com.google.gwt.user.client.ui.SuggestOracle;
import com.google.gwt.user.client.ui.SuggestOracle.Suggestion;
import com.google.gwt.user.client.ui.TextBox;
import com.google.gwt.user.client.ui.TextBoxBase;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
* Extension of suggestBox simulating a traditional single-select list .
* @author amal
* @version 1.0
*/
public final class MyGwtSuggestBox extends SuggestBox
{

private String value;
private HashMap<String, String> itemValues;
private HashMap<String, String> valueItems;
private MultiWordSuggestOracle oracle;

public MyGwtSuggestBox(String value,
HashMap<String, String> itemValues,
HashMap<String, String> valueItems,
MultiWordSuggestOracle oracle)
{
this.value = value;
this.itemValues = itemValues;
this.valueItems = valueItems;
this.oracle = oracle;
}
private ChangeHandler changeHandler = new ChangeHandler()
{

/**
* check if the current value is in set of possible values , else rollback
*/
public void onChange(ChangeEvent event)
{
TextBox x = (TextBox) event.getSource();
String text = x.getText().trim();
if (value == null)
{
value = "";
}
if (itemValues.keySet().contains(text))
{
value = text;
}
else
{
x.setText(value);
}
}
};
private KeyUpHandler keyUpHandler = new KeyUpHandler()
{

public void onKeyUp(KeyUpEvent event)
{
MyGwtSuggestBox x = (MyGwtSuggestBox) event.getSource();
if (x.getText().trim().equals("") && event.isDownArrow() && !((DefaultSuggestionDisplay) x.
getSuggestionDisplay()).isSuggestionListShowing())
{
x.showSuggestionList();
}
}
};
private SelectionHandler<SuggestOracle.Suggestion> selectionHandler = new SelectionHandler<SuggestOracle.Suggestion>()
{

public void onSelection(SelectionEvent<Suggestion> event)
{
SuggestBox x = (SuggestBox) event.getSource();
String text = x.getText().trim();
if (value == null)
{
value = "";
}
if (itemValues.keySet().contains(text))
{
value = text;
}
else
{
x.setText(value);
}
}
};
private HandlerRegistration regChange = null;
private HandlerRegistration regFocus = null;

;
private HandlerRegistration regKeyPress = null;
private HandlerRegistration regSelection = null;

public MyGwtSuggestBox()
{
this(false);
}

public MyGwtSuggestBox(boolean enforceInputValidation)
{
super();
itemValues = new HashMap<String, String>();
valueItems = new HashMap<String, String>();
oracle = (MultiWordSuggestOracle) super.getSuggestOracle();
regKeyPress = super.addKeyUpHandler(keyUpHandler);
if (!enforceInputValidation)
{
regChange = super.getTextBox().addChangeHandler(changeHandler);
regSelection = super.addSelectionHandler(selectionHandler);
}
}

public void removeInputValidation()
{
if (null != regChange)
{
regChange.removeHandler();
regChange = null;
}
if (null != regFocus)
{
regFocus.removeHandler();
regFocus = null;
}
}

public MyGwtSuggestBox(SuggestOracle oracle, TextBoxBase box,
SuggestionDisplay suggestDisplay)
{
throw new UnsupportedOperationException("Not Supported.Yet.");
}

public MyGwtSuggestBox(SuggestOracle oracle, TextBoxBase box)
{
throw new UnsupportedOperationException("Not Supported.Yet.");
}

public MyGwtSuggestBox(SuggestOracle oracle)
{
throw new UnsupportedOperationException("Not Supported.Yet.");
}

public void removeAllItems()
{
itemValues = new HashMap<String, String>();
valueItems = new HashMap<String, String>();
oracle.clear();

}

public void addItems(List<String> items)
{
for (String item : items)
{
addItem(item);
}
}

public void addItems(String[] items)
{
for (String item : items)
{
addItem(item);
}

}

public void addItems(Map<String, String> keyItems)
{
for (String key : keyItems.keySet())
{
addItem(keyItems.get(key), key);
}
}

public void addItem(String item)
{
if (itemValues.containsKey(item))
{
throw new RuntimeException("Duplicate item in list : " + item);
}
if (valueItems.containsKey(item))
{
throw new RuntimeException("Duplicate value in list : " + item);
}
itemValues.put(item, item);
valueItems.put(item, item);
oracle.add(item);
oracle.setDefaultSuggestionsFromText(itemValues.keySet());
}

public void addItem(String item, String key)
{
if (itemValues.containsKey(item))
{
throw new RuntimeException("Duplicate item in list : " + item);
}
if (valueItems.containsKey(key))
{
throw new RuntimeException("Duplicate value in list : " + key);
}
itemValues.put(item, key);
valueItems.put(key, item);
oracle.add(item);
oracle.setDefaultSuggestionsFromText(itemValues.keySet());
}

public String getSelectedValue()
{
return itemValues.get(super.getText());
}

public void setSelectedValue(String key)
{
super.setText(valueItems.get(key));
}

public void clear()
{
super.setText("");
}
}

A custom confirm dialog using GWT

2010-07-28T10:56:00.000-07:00

Ever grew frustrated by the lack of customizations available of the window.confirm() dialog ? Here's a customizable confirm dialog for gwt apps.


/**
*PUBLIC SOFTWARE
*
*This source code has been placedin the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/
import com.google.gwt.event.dom.client.ClickEvent;
import com.google.gwt.event.dom.client.ClickHandler;
import com.google.gwt.event.logical.shared.CloseHandler;
import com.google.gwt.user.client.ui.*;

/**
* @author amal
* @version 1.0
*/
public final class MyGwtConfirmDialog extends DialogBox
{

private Button primaryBtn;
private Button secondaryBtn;
private VerticalPanel mainPanel;
private HorizontalPanel btnPanel;
private HTML messageLbl;
private boolean primaryActionFired = false;
private boolean secondaryActionFired = false;

public boolean primaryActionFired()
{
return primaryActionFired;
}

public boolean secondaryActionFired()
{
return secondaryActionFired;
}

/**
*
* @param title
* @param message
* @param primaryActionText
* @param secondaryActionText
* @param closeHandler
*
* sample usage - retrieving the confirmation status
* <pre>
* CloseHandler<PopupPanel> closeHandler=new CloseHandler<PopupPanel>()
*          {
*
*               public void onClose(CloseEvent<PopupPanel> event)
*                 {
*                  MyGwtConfirmDialog x=(MyGwtConfirmDialog)event.getSource();
*                  Window.alert("primary "+x.primaryActionFired()+" ; secondary "+x.secondaryActionFired());
*                 }
*           };
*         MyGwtConfirmDialog dia=new MyGwtConfirmDialog(<title>,<message>,<okText>,<cancelText>,closeHandler);
* </pre>
*/
public MyGwtConfirmDialog(String title, String message,
String primaryActionText,
String secondaryActionText,
CloseHandler<PopupPanel> closeHandler)
{
super(false, true);
super.addCloseHandler(closeHandler);
super.setText(title);
mainPanel = new VerticalPanel();
messageLbl = new HTML(message);
btnPanel = new HorizontalPanel();
mainPanel.add(messageLbl);
mainPanel.add(btnPanel);
primaryBtn = new Button(primaryActionText, new ClickHandler()
{

public void onClick(ClickEvent event)
{
primaryActionFired = true;
MyGwtConfirmDialog.this.hide();
}
});
secondaryBtn = new Button(secondaryActionText, new ClickHandler()
{

public void onClick(ClickEvent event)
{
secondaryActionFired = true;
MyGwtConfirmDialog.this.hide();
}
});
btnPanel.add(primaryBtn);
btnPanel.add(secondaryBtn);
btnPanel.setCellHorizontalAlignment(primaryBtn,
HorizontalPanel.ALIGN_RIGHT);
btnPanel.setCellHorizontalAlignment(secondaryBtn,
HorizontalPanel.ALIGN_LEFT);
super.setWidget(mainPanel);
mainPanel.setHeight("100px");
mainPanel.setWidth("300px");
btnPanel.setHeight("30px");
btnPanel.setVerticalAlignment(HorizontalPanel.ALIGN_BOTTOM);
btnPanel.addStyleName("dia-btnPanel");
primaryBtn.addStyleName("dia-primaryBtn");
secondaryBtn.addStyleName("dia-secondaryBtn");
messageLbl.addStyleName("dia-message");
super.setGlassEnabled(true);
super.setAnimationEnabled(true);
}

/**
*
* @param message
* @param closeHandler
* @see MyGwtConfirmDialog#MyGwtConfirmDialog(java.lang.String, java.lang.String, java.lang.String, java.lang.String, com.google.gwt.event.logical.shared.CloseHandler)
*/
public MyGwtConfirmDialog(String message,
CloseHandler<PopupPanel> closeHandler)
{
this("Confirmation", message, "Ok", "Cancel", closeHandler);
}

/**
* should be used for displaying the dialog .
*/
public void paint()
{
primaryActionFired = false;
secondaryActionFired = false;
super.center();
primaryBtn.setFocus(true);
}

/**
*
* @param width
*/
public void setMainPanelWidth(String width)
{
mainPanel.setWidth(width);
}
}

GWT Custom Datebox

2010-07-28T08:28:00.000-07:00

Here's an implemenation of a DateBox in GWT , specially designed for keyboard users . Like the ones who cant bother to maneuver a mouse .

The field recognizes multiple date formats , and even some real shorthands - like type in 010203 , and the date is set to Jan 01,2003 .


/**
*PUBLIC SOFTWARE
*
*This source code has been placed in the public domain. You can use, modify, and distribute
*the source code and executable programs based on the source code.
*
*However, note the following:
*
*DISCLAIMER OF WARRANTY
*
* This source code is provided "as is" and without warranties as to performance
* or merchantability. The author and/or distributors of this source code may
* have made statements about this source code. Any such statements do not constitute
* warranties and shall not be relied on by the user in deciding whether to use
* this source code.This source code is provided without any express or implied
* warranties whatsoever. Because of the diversity of conditions and hardware
* under which this source code may be used, no warranty of fitness for a
* particular purpose is offered. The user is advised to test the source code
* thoroughly before relying on it. The user must assume the entire risk of
* using the source code.
*
*/
import com.google.gwt.event.dom.client.ChangeEvent;
import com.google.gwt.event.dom.client.ChangeHandler;
import com.google.gwt.event.shared.HandlerRegistration;
import com.google.gwt.i18n.client.DateTimeFormat;
import com.google.gwt.user.client.ui.*;
import java.util.Date;

/**
* DateBox implemenation for keyboard power users.
* @author
* @version 1.0
*/
public final class MyGwtDateBox extends TextBox
{

private static final long MS_PER_SEC = 1000;
private static final long MS_PER_MIN = MS_PER_SEC * 60;
private static final long MS_PER_HOUR = MS_PER_MIN * 60;
private static final long MS_PER_DAY = MS_PER_HOUR * 24;
/**
* date formats recognized .
*/
private static String[] formats = new String[]
{
"dd-MM-yyyy",
"dd-MMM-yyyy",
"dd.MM.yyyy",
"dd.MMM.yyyy",
"dd/MM/yyyy",
"dd/MMM/yyyy",
"dd MM yyyy",
"dd MMM yyyy",
"dd-MMMM-yyyy",
"dd.MMMM.yyyy",
"dd/MMMM/yyyy",
"dd MMMM yyyy",
"MMM dd yyyy",
"MMMM dd yyyy",
"MMM dd,yyyy",
"MMMM dd,yyyy"
};
/**
* output dateFormat
*/
private static DateTimeFormat dtf = DateTimeFormat.getFormat("dd-MMM-yyyy");

public static DateTimeFormat getDateTimeFormat()
{
return dtf;
}
private DateTimeFormat fullWeekDay = DateTimeFormat.getFormat("EEEE");
private DateTimeFormat shortWeekDay = DateTimeFormat.getFormat("EEE");
private Date today = today();
private Date yesterday = yesterday();
private Date tommorrow = tommorrow();
private Date value;
boolean nullAllowed = false;
/**
*
*/
private ChangeHandler changeHandler = new ChangeHandler()
{

/**
* try inferring the date from the enterd String , if not possible rollback to previous value.
*/
public void onChange(ChangeEvent event)
{
MyGwtDateBox x = (MyGwtDateBox) event.getSource();
String text = x.getText();
if (nullAllowed)
{
if (null == text || text.trim().equals(""))
{
return;
}
}
if (text == null)
{
text = dtf.format(new Date());
}
text = text.trim();
text.replaceAll("\\s+", "\\s");
text = handleNoSpacesString(text);
try
{
text = handleShortHands(text);
text = adjustYear(text);
text = dtf.format(DateTimeFormat.getFormat(inferFormat(text)).
parse(text));
value = dtf.parse(text);
x.setText(text);
}
catch (Exception e)
{
x.setText(dtf.format(value));
}
}
};
private HandlerRegistration regChange;

public MyGwtDateBox(int maxLength, int visibleLength)
{
throw new UnsupportedOperationException("not supported");
}

public MyGwtDateBox(String text, int maxLength, int visibleLength)
{
throw new UnsupportedOperationException("not supported");
}

public MyGwtDateBox(int maxLength)
{
throw new UnsupportedOperationException("not supported");
}

public MyGwtDateBox(String text, int maxLength)
{
throw new UnsupportedOperationException("not supported");
}

public MyGwtDateBox(String text)
{
throw new UnsupportedOperationException("not supported");
}

public MyGwtDateBox()
{
this(new Date());
}

public MyGwtDateBox(Date d)
{
super();
super.setText(dtf.format(d));
value = d;
regChange = super.addChangeHandler(changeHandler);
}

public void setNullAllowed(boolean nullAllowed)
{
this.nullAllowed = nullAllowed;
}

String handleNoSpacesString(String x)
{
if (x.matches("^\\d+$"))
{
if (x.length() == 6 || x.length() == 8)
{
return x.substring(0, 2) + " " + x.substring(2, 4) + " " + x.
substring(4);
}
}
return x;
}

/**
* the short-hand evaluation done in accordance with the values entered in AppMessages.properties
* @param x
* @return
*/
String handleShortHands(String x)
{
boolean previousFlag = false;
if (x.equalsIgnoreCase(MESSAGES.today()))
{
return dtf.format(today);
}
if (x.equalsIgnoreCase(MESSAGES.tommorrow()))
{
return dtf.format(tommorrow);
}
if (x.equalsIgnoreCase(MESSAGES.yesterday()))
{
return dtf.format(yesterday);
}
if (x.startsWith(MESSAGES.previous()))
{
previousFlag = true;
x = x.split("\\s")[1];
}
if (x.startsWith(MESSAGES.next()))
{
x = x.split("\\s")[1];
}
if (!x.trim().equals("") && MESSAGES.weekdaysString().
contains(x + ";"))
{
Date dt = previousFlag ? new Date(yesterday.getTime()) : new Date(tommorrow.
getTime());
long increment = previousFlag ? MS_PER_DAY * -1 : MS_PER_DAY;
while (!fullWeekDay.format(dt).equalsIgnoreCase(x))
{
dt.setTime(dt.getTime() + increment);
}
return dtf.format(dt);
}
if (!x.trim().equals("") && MESSAGES.weekdaysStringShort().
contains(x + ";"))
{
Date dt = previousFlag ? new Date(yesterday.getTime()) : new Date(tommorrow.
getTime());
long increment = previousFlag ? MS_PER_DAY * -1 : MS_PER_DAY;
while (!shortWeekDay.format(dt).equalsIgnoreCase(x))
{
dt.setTime(dt.getTime() + increment);
}
return dtf.format(dt);
}
return x;
}

/**
* example transformations
* 19 -> 2019
* 20 -> 2020
* 21 -> 1921
* @param x
* @return
*/
String adjustYear(String x)
{
if (x.matches("^.*\\D\\d\\d$"))
{
int year = Integer.parseInt(x.substring(x.length() - 2, x.length()));
x = x.substring(0, x.length() - 2) + (year < 21 ? "20" : "19") + x.
substring(x.length() - 2, x.length());
}
return x;
}

String inferFormat(String x)
{
for (String format : formats)
{
try
{
DateTimeFormat.getFormat(format).parse(x);
return format;
}
catch (Exception e)
{
//ignore
              }
}
throw new RuntimeException("Unparseable date , " + x);
}

static Date today()
{
return new Date();
}

static Date yesterday()
{
Date tmp = new Date();
tmp.setTime(tmp.getTime() - MS_PER_DAY);
return new Date(tmp.getTime());
}

static Date tommorrow()
{
Date tmp = new Date();
tmp.setTime(tmp.getTime() + MS_PER_DAY);
return new Date(tmp.getTime());
}

public Date getDate()
{
return dtf.parse(super.getText());
}

public void setDate(Date x)
{
super.setText(dtf.format(x));
}
}

class MESSAGES
{

static String today()
{
return "today";
}

static String tommorrow()
{
return "tomm";
}

static String yesterday()
{
return "yesterday";
}

static String next()
{
return "next";
}

static String previous()
{
return "previous";
}

static String weekdaysString()
{
return "sunday;monday;tuesday;wednesday;thursday;friday;saturday;";
}

static String weekdaysStringShort()
{
return "sun;mon;tue;wed;thu;fri;sat;";
}
}