Introduction to java beans

Prepared by :- Hitesh Parmar
hitesh.parmar915@gmail.com
@i_hiteshparmar

 What is a Java Bean.
 Components and classes with respect to Java Bean.
 Java.Beans(Package).
 The Component and its type in Java Beans.
 Useful Terms while Using Java Beans.
 Software Components
 Visually Manipulated, Builder Tools
 Support

 “It’s a Component Architecture of Java which allow
you to define the Component ”
 Java Bean is nothing but the Java Class.
 Example:-
 Swing are all the Java Bean component
 Component (Button,TextField,Label)

 Java Bean classes follow certain Rule or Condition.
 All java Bean classes must Implement the Serializable
Interface.
 Component may be used by some apllication
builder.
 A bean has a no argument constructor.
Serializing
CLASS
Class Object
Component
Object

 Java Bean API makes it possible to write the
component s/w in a java programming language.
 This package will be used depending upon the need
of the Application (based on funcion of bean classes).
 Now when its only the use of the property or the
Getter & Setter Method at that time you might not
even make a use of this package.

 The component is nothing but the group of classes.
 Example:- Jbutton(it’s a component not a class).
 In order to a swing Button there are whole lot of class
are involved to build this Jbutton.
 Component is a single Functionality provided by
many different classes
 Component is a group of classses that interact with
eachother to fulfill the single purpose.

 Application developer uses different beans in his
application using the Java Beans.
 You can build two types of Components.
Component
GUI based
Non GUI based
Extends
Component

 Properties
 Event
 Persistence
 Introspection
 Customization

 Discrete, named attributes that determine the
appearance ,behavior and state of a component.
 Accessible programmatically through accessor
methods.
 Accessible visually through property sheets.

 Simple Properties
 Boolean Properties
 Indexed Properties

 1 Simple Properties:-
 Represent a single value.
 The accessor methods should follow standard naming
conventions.
public <PropertyType> get<PropertyName>();
public void set<PropertyName>(<PropertyType> value);
Example:
public String getHostName();
public void setHostName( String hostName );

 2 BooleanProperties:-
 They are simple properties
 The getter methods follow an optional design pattern
public boolean is<PropertyName>();
Example:
public boolean isConnected();

 3 Indexed Properties:-
 Represent an array of values
public <PropertyElement> get<PropertyName>(int index);
public void set<PropertyName>(int index,<PropertyElement> value);
public <PropertyElement>[] get<PropertyName>();
public void set<PropertyName>(<PropertyElement>[] values);
Example:
public Color setPalette(int index);
public void setPalette(int index,Color value);
public Color[] getPalette();
public void setPalette(Color[] values);

 Bound:-
 a bound property notifies other objects when its value
changes
 generates a PropertyChange event with property name,
old value and new value
 Constrained:-
 an object with constrained properties allows other
objects to veto a constrained property value change
 Constrained property listeners can veto a change by
throwing a PropertyVetoException

 Two types of objects are involved:
 “Source” objects.
 “Listener” objects.
 Message sent from one object to another.
 Sender fires event, recipient (listener) handles the
event
 There may be many listeners.

Event
source
Event
listener
Fire event
Event
Object
Register listener
Sender fires event, recipient (listener) handles
the event

 Persistance
 Your Bean should be able to store its state, which means
there should be the serializable interface.
 Upon the Bean a builder tool should be able to make a
reflaction and be able to create an object of your
component.
 [Ex. Drag and drop a component in to a design area and
the builder tool should be able to create the instance of
that component and be able to display the property of
that bean via reflaction.]

 Customization
 Using the Bean customization, you can specify what
methods or the properties that you want to expose at rhe
run time environment, so such property will be
displayed in the propertysheet.
 Introspection
 Is nothing but a reflection using which the builder tool
can display all the events and the properties of the
component.

 Reflection API
 It helps us to find out what are the contents of the class,
so you can findout what are the methods, constructors
and variables in the class and you can find out the
details in return.
 Due to the process of the reflection builder tool can be
able to display what are the property of the Component
in the property sheet and also provides the details
regarding the Events and methods.

 Buttons
 Text Fields
 List Boxes
 Scroll Bars
 Dialogs

BeanBoxToolBoxToolBox BeanBox
Property Sheet

 BDK - Sun
 NetBeans – www.netbeans.org
 Jbuilder - Inprise
 Super Mojo - Penumbra Software
 Visual Age for Java - IBM
 Visual Cafe - Symantec Corporation
 JDeveloper Suite - Oracle

Introduction to java beans

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