Sample code for Java custom listeners

Java user-defined event listener complete example

Java user-defined event listener complete example--sunfruit many of the user-defined events are not examples, or examples are incomplete, the following is a complete example, and write a comment for reference, the complete instance source code is as follows:

Package demo;

Import Java.util.EventObject;

/**

* Title: Event Processing class, inheriting the event base class

* Description:

* Copyright:copyright (c) 2005

* Company:cuijiang

* @author not attributable

* @version 1.0

*/

public class Demoevent extends EventObject

{

Private Object obj;

Private String SName;

Public demoevent (Object source,string sName) {

Super (source);

obj = source;

This.sname=sname;

}

Public Object GetSource ()

{

return obj;

}

public void Say ()

{

System.out.println ("This is the Say method ...");

}

Public String GetName ()

{

return sName;

}

}

Package demo;

Import Java.util.EventListener;

/**

* Title: Listener interface

* Description:

* Copyright:copyright (c) 2005

* Company:cuijiang

* @author not attributable

* @version 1.0

*/

Public interface Demolistener extends eventlistener{

public void Demoevent (demoevent DM);

}

Package demo;

Import java.util.*;

/**

* Title: Class using the event

* Description: This class implements the addition of listeners and the execution of listener methods, and implements events due to property changes

* Description: Be aware of synchronization issues when adding, deleting, and executing listeners

* Copyright:copyright (c) 2005

* Company:cuijiang

* @author not attributable

* @version 1.0

*/

public class demosource{

Private vector repository = new vector ();

Private Demolistener DL;

Private String sname= "";

Public Demosource ()

{

}

Register the Listener, if you use ArrayList instead of vectors, pay attention to synchronization issues

public void Adddemolistener (Demolistener dl)

{

Repository.addelement (DL);//This step should pay attention to the synchronization problem

}

If you use ArrayList instead of vectors, be aware of synchronization issues

public void Notifydemoevent (Demoevent event) {

enumeration enum = Repository.elements ();//This step should pay attention to the synchronization problem

while (Enum.hasmoreelements ())

{

DL = (Demolistener) enum.nextelement ();

Dl.demoevent (event);

}

}

Delete the listener, if you are using ArrayList instead of vectors, pay attention to the synchronization problem

public void Removedemolistener (Demolistener dl)

{

Repository.remove (DL);//This step should pay attention to the synchronization problem

}

/**

* Set Properties

* @param str1 String

*/

public void SetName (String str1)

{

Boolean bool=false;

if (str1==null && sname!=null) bool=true;

else if (str1!=null && sname==null) bool=true;

else if (!sname.equals (str1)) bool=true;

THIS.SNAME=STR1;

Execute event If change occurs

if (bool) notifydemoevent (new Demoevent (This,sname));

}

Public String GetName ()

{

return sName;

}

}

Package demo;

Import Java.lang.Thread;

/**

* Title: Test class

* Description: Tested for events caused by changing attributes

* Copyright:copyright (c) 2005

* Company:cuijiang

* @author not attributable

* @version 1.0

*/

public class Testdemo

Implements Demolistener {

Private Demosource DS;

Public Testdemo ()

{

Ds=new Demosource ();

Ds.adddemolistener (this);

SYSTEM.OUT.PRINTLN ("Add listener Complete");

try {

Thread.Sleep (3000);

Changing properties, triggering events

Ds.setname ("Change attribute, trigger event");

}

catch (Interruptedexception ex) {

Ex.printstacktrace ();

}

Ds.adddemolistener (this);

SYSTEM.OUT.PRINTLN ("Add listener complete 2″);

try {

Thread.Sleep (3000);

Changing properties, triggering events

Ds.setname ("Change attribute, trigger event 2″);

}

catch (Interruptedexception ex) {

Ex.printstacktrace ();

}

Ds.removedemolistener (this);

SYSTEM.OUT.PRINTLN ("Add listener complete 3″);

try {

Thread.Sleep (3000);

Changing properties, triggering events

Ds.setname ("Change attribute, trigger event 3″);

}

catch (Interruptedexception ex) {

Ex.printstacktrace ();

}

}

public static void Main (String args[])

{

New Testdemo ();

}

/**

* Demoevent

*

* @param DM demoevent

* @todo Implement this test. Demolistener method

*/

public void Demoevent (Demoevent dm) {

SYSTEM.OUT.PRINTLN ("Event handling method");

System.out.println (Dm.getname ());

Dm.say ();

}

}

Sample code for Java custom listeners