java.beans

Class PropertyDescriptor

java.lang.Object

java.beans.FeatureDescriptor

java.beans.PropertyDescriptor

Direct Known Subclasses:

IndexedPropertyDescriptor

public class PropertyDescriptor
extends FeatureDescriptor

A PropertyDescriptor describes one property that a Java Bean exports via a pair of accessor methods.

Constructor Summary

Constructors

Constructor and Description
PropertyDescriptor(String propertyName, Class<?> beanClass) Constructs a PropertyDescriptor for a property that follows the standard Java convention by having getFoo and setFoo accessor methods.
PropertyDescriptor(String propertyName, Class<?> beanClass, String readMethodName, String writeMethodName) This constructor takes the name of a simple property, and method names for reading and writing the property.
PropertyDescriptor(String propertyName, Method readMethod, Method writeMethod) This constructor takes the name of a simple property, and Method objects for reading and writing the property.

Method Summary

Modifier and Type	Method and Description
PropertyEditor	createPropertyEditor(Object bean) Constructs an instance of a property editor using the current property editor class.
boolean	equals(Object obj) Compares this PropertyDescriptor against the specified object.
Class<?>	getPropertyEditorClass() Gets any explicit PropertyEditor Class that has been registered for this property.
Class<?>	getPropertyType() Returns the Java type info for the property.
Method	getReadMethod() Gets the method that should be used to read the property value.
Method	getWriteMethod() Gets the method that should be used to write the property value.
int	hashCode() Returns a hash code value for the object.
boolean	isBound() Updates to "bound" properties will cause a "PropertyChange" event to get fired when the property is changed.
boolean	isConstrained() Attempted updates to "Constrained" properties will cause a "VetoableChange" event to get fired when the property is changed.
void	setBound(boolean bound) Updates to "bound" properties will cause a "PropertyChange" event to get fired when the property is changed.
void	setConstrained(boolean constrained) Attempted updates to "Constrained" properties will cause a "VetoableChange" event to get fired when the property is changed.
void	setPropertyEditorClass(Class<?> propertyEditorClass) Normally PropertyEditors will be found using the PropertyEditorManager.
void	setReadMethod(Method readMethod) Sets the method that should be used to read the property value.
void	setWriteMethod(Method writeMethod) Sets the method that should be used to write the property value.

Methods inherited from class java.beans.FeatureDescriptor

attributeNames, getDisplayName, getName, getShortDescription, getValue, isExpert, isHidden, isPreferred, setDisplayName, setExpert, setHidden, setName, setPreferred, setShortDescription, setValue, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

PropertyDescriptor

public PropertyDescriptor(String propertyName,
                          Class<?> beanClass)
                   throws IntrospectionException

Constructs a PropertyDescriptor for a property that follows the standard Java convention by having getFoo and setFoo accessor methods. Thus if the argument name is "fred", it will assume that the writer method is "setFred" and the reader method is "getFred" (or "isFred" for a boolean property). Note that the property name should start with a lower case character, which will be capitalized in the method names.

Parameters:

propertyName - The programmatic name of the property.

beanClass - The Class object for the target bean. For example sun.beans.OurButton.class.

Throws:

IntrospectionException - if an exception occurs during introspection.

PropertyDescriptor

public PropertyDescriptor(String propertyName,
                          Class<?> beanClass,
                          String readMethodName,
                          String writeMethodName)
                   throws IntrospectionException

This constructor takes the name of a simple property, and method names for reading and writing the property.

Parameters:

propertyName - The programmatic name of the property.

beanClass - The Class object for the target bean. For example sun.beans.OurButton.class.

readMethodName - The name of the method used for reading the property value. May be null if the property is write-only.

writeMethodName - The name of the method used for writing the property value. May be null if the property is read-only.

Throws:

IntrospectionException - if an exception occurs during introspection.

PropertyDescriptor

public PropertyDescriptor(String propertyName,
                          Method readMethod,
                          Method writeMethod)
                   throws IntrospectionException

This constructor takes the name of a simple property, and Method objects for reading and writing the property.

Parameters:

propertyName - The programmatic name of the property.

readMethod - The method used for reading the property value. May be null if the property is write-only.

writeMethod - The method used for writing the property value. May be null if the property is read-only.

Throws:

IntrospectionException - if an exception occurs during introspection.

Method Detail

getPropertyType

public Class<?> getPropertyType()

Returns the Java type info for the property. Note that the Class object may describe primitive Java types such as int. This type is returned by the read method or is used as the parameter type of the write method. Returns null if the type is an indexed property that does not support non-indexed access.

Returns:

the Class object that represents the Java type info, or null if the type cannot be determined

getReadMethod

public Method getReadMethod()

Gets the method that should be used to read the property value.

Returns:

The method that should be used to read the property value. May return null if the property can't be read.

setReadMethod

public void setReadMethod(Method readMethod)
                   throws IntrospectionException

Sets the method that should be used to read the property value.

Parameters:

readMethod - The new read method.

Throws:

IntrospectionException - if the read method is invalid

getWriteMethod

public Method getWriteMethod()

Gets the method that should be used to write the property value.

Returns:

The method that should be used to write the property value. May return null if the property can't be written.

setWriteMethod

public void setWriteMethod(Method writeMethod)
                    throws IntrospectionException

Sets the method that should be used to write the property value.

Parameters:

writeMethod - The new write method.

Throws:

IntrospectionException - if the write method is invalid

isBound

public boolean isBound()

Updates to "bound" properties will cause a "PropertyChange" event to get fired when the property is changed.

Returns:

True if this is a bound property.

setBound

public void setBound(boolean bound)

Updates to "bound" properties will cause a "PropertyChange" event to get fired when the property is changed.

Parameters:

bound - True if this is a bound property.

isConstrained

public boolean isConstrained()

Attempted updates to "Constrained" properties will cause a "VetoableChange" event to get fired when the property is changed.

Returns:

True if this is a constrained property.

setConstrained

public void setConstrained(boolean constrained)

Attempted updates to "Constrained" properties will cause a "VetoableChange" event to get fired when the property is changed.

Parameters:

constrained - True if this is a constrained property.

setPropertyEditorClass

public void setPropertyEditorClass(Class<?> propertyEditorClass)

Normally PropertyEditors will be found using the PropertyEditorManager. However if for some reason you want to associate a particular PropertyEditor with a given property, then you can do it with this method.

Parameters:

propertyEditorClass - The Class for the desired PropertyEditor.

getPropertyEditorClass

public Class<?> getPropertyEditorClass()

Gets any explicit PropertyEditor Class that has been registered for this property.

Returns:

Any explicit PropertyEditor Class that has been registered for this property. Normally this will return "null", indicating that no special editor has been registered, so the PropertyEditorManager should be used to locate a suitable PropertyEditor.

createPropertyEditor

public PropertyEditor createPropertyEditor(Object bean)

Constructs an instance of a property editor using the current property editor class.

If the property editor class has a public constructor that takes an Object argument then it will be invoked using the bean parameter as the argument. Otherwise, the default constructor will be invoked.

Parameters:

bean - the source object

Returns:

a property editor instance or null if a property editor has not been defined or cannot be created

Since:

1.5

equals

public boolean equals(Object obj)

Compares this PropertyDescriptor against the specified object. Returns true if the objects are the same. Two PropertyDescriptors are the same if the read, write, property types, property editor and flags are equivalent.

Overrides:

equals in class Object

Parameters:

obj - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

Since:

1.4

See Also:

Object.hashCode(), HashMap

hashCode

public int hashCode()

Returns a hash code value for the object. See Object.hashCode() for a complete description.

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

Since:

1.5

See Also:

Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)