public class

LazyDynaClass

extends BasicDynaClass
implements MutableDynaClass
java.lang.Object
   ↳ org.apache.commons.beanutils.BasicDynaClass
     ↳ org.apache.commons.beanutils.LazyDynaClass

Class Overview

DynaClass which implements the MutableDynaClass interface.

A MutableDynaClass is a specialized extension to DynaClass that allows properties to be added or removed dynamically.

This implementation has one slightly unusual default behaviour - calling the getDynaProperty(name) method for a property which doesn't exist returns a DynaProperty rather than null. The reason for this is that BeanUtils calls this method to check if a property exists before trying to set the value. This would defeat the object of the LazyDynaBean which automatically adds missing properties when any of its set() methods are called. For this reason the isDynaProperty(name) method has been added to this implementation in order to determine if a property actually exists. If the more normal behaviour of returning null is required, then this can be achieved by calling the setReturnNull(true).

The add(name, type, readable, writable) method is not implemented and always throws an UnsupportedOperationException. I believe this attributes need to be added to the DynaProperty class in order to control read/write facilities.

See Also

Summary

Fields
protected boolean restricted Controls whether changes to this DynaClass's properties are allowed.
protected boolean returnNull

Controls whether the getDynaProperty() method returns null if a property doesn't exist - or creates a new one.
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Inherited Fields
From class org.apache.commons.beanutils.BasicDynaClass
Public Constructors
LazyDynaClass()
Construct a new LazyDynaClass with default parameters.
LazyDynaClass(String name)
Construct a new LazyDynaClass with the specified name.
LazyDynaClass(String name, Class dynaBeanClass)
Construct a new LazyDynaClass with the specified name and DynaBean class.
LazyDynaClass(String name, DynaProperty[] properties)
Construct a new LazyDynaClass with the specified name and properties.
LazyDynaClass(String name, Class dynaBeanClass, DynaProperty[] properties)
Construct a new LazyDynaClass with the specified name, DynaBean class and properties.
Public Methods
void add(String name, Class type, boolean readable, boolean writeable)

Add a new dynamic property with the specified data type, readability, and writeability.

void add(String name, Class type)
Add a new dynamic property with the specified data type, but with no restrictions on readability or writeability.
void add(String name)
Add a new dynamic property with no restrictions on data type, readability, or writeability.
DynaProperty getDynaProperty(String name)

Return a property descriptor for the specified property.

boolean isDynaProperty(String name)

Indicate whether a property actually exists.

boolean isRestricted()

Is this DynaClass currently restricted.

boolean isReturnNull()
Should this DynaClass return a null from the getDynaProperty(name) method if the property doesn't exist.
void remove(String name)
Remove the specified dynamic property, and any associated data type, readability, and writeability, from this dynamic class.
void setRestricted(boolean restricted)

Set whether this DynaClass is currently restricted.

void setReturnNull(boolean returnNull)
Set whether this DynaClass should return a null from the getDynaProperty(name) method if the property doesn't exist.
Protected Methods
void add(DynaProperty property)
Add a new dynamic property.
[Expand]
Inherited Methods
From class org.apache.commons.beanutils.BasicDynaClass
From class java.lang.Object
From interface org.apache.commons.beanutils.DynaClass
From interface org.apache.commons.beanutils.MutableDynaClass

Fields

protected boolean restricted

Controls whether changes to this DynaClass's properties are allowed.

protected boolean returnNull

Controls whether the getDynaProperty() method returns null if a property doesn't exist - or creates a new one.

Default is false.

Public Constructors

public LazyDynaClass ()

Construct a new LazyDynaClass with default parameters.

public LazyDynaClass (String name)

Construct a new LazyDynaClass with the specified name.

Parameters
name Name of this DynaBean class

public LazyDynaClass (String name, Class dynaBeanClass)

Construct a new LazyDynaClass with the specified name and DynaBean class.

Parameters
name Name of this DynaBean class
dynaBeanClass The implementation class for new instances

public LazyDynaClass (String name, DynaProperty[] properties)

Construct a new LazyDynaClass with the specified name and properties.

Parameters
name Name of this DynaBean class
properties Property descriptors for the supported properties

public LazyDynaClass (String name, Class dynaBeanClass, DynaProperty[] properties)

Construct a new LazyDynaClass with the specified name, DynaBean class and properties.

Parameters
name Name of this DynaBean class
dynaBeanClass The implementation class for new intances
properties Property descriptors for the supported properties

Public Methods

public void add (String name, Class type, boolean readable, boolean writeable)

Add a new dynamic property with the specified data type, readability, and writeability.

N.B.Support for readable/writeable properties has not been implemented and this method always throws a UnsupportedOperationException.

I'm not sure the intention of the original authors for this method, but it seems to me that readable/writable should be attributes of the DynaProperty class (which they are not) and is the reason this method has not been implemented.

Parameters
name Name of the new dynamic property
type Data type of the new dynamic property (null for no restrictions)
readable Set to true if this property value should be readable
writeable Set to true if this property value should be writeable
Throws
UnsupportedOperationException anytime this method is called

public void add (String name, Class type)

Add a new dynamic property with the specified data type, but with no restrictions on readability or writeability.

Parameters
name Name of the new dynamic property
type Data type of the new dynamic property (null for no restrictions)
Throws
IllegalArgumentException if name is null
IllegalStateException if this DynaClass is currently restricted, so no new properties can be added

public void add (String name)

Add a new dynamic property with no restrictions on data type, readability, or writeability.

Parameters
name Name of the new dynamic property
Throws
IllegalArgumentException if name is null
IllegalStateException if this DynaClass is currently restricted, so no new properties can be added

public DynaProperty getDynaProperty (String name)

Return a property descriptor for the specified property.

If the property is not found and the returnNull indicator is true, this method always returns null.

If the property is not found and the returnNull indicator is false a new property descriptor is created and returned (although its not actually added to the DynaClass's properties). This is the default beahviour.

The reason for not returning a null property descriptor is that BeanUtils uses this method to check if a property exists before trying to set it - since these Lazy implementations automatically add any new properties when they are set, returning null from this method would defeat their purpose.

Parameters
name Name of the dynamic property for which a descriptor is requested
Returns
  • The dyna property for the specified name
Throws
IllegalArgumentException if no property name is specified

public boolean isDynaProperty (String name)

Indicate whether a property actually exists.

N.B. Using getDynaProperty(name) == null doesn't work in this implementation because that method might return a DynaProperty if it doesn't exist (depending on the returnNull indicator).

Parameters
name The name of the property to check
Returns
  • true if there is a property of the specified name, otherwise false
Throws
IllegalArgumentException if no property name is specified

public boolean isRestricted ()

Is this DynaClass currently restricted.

If restricted, no changes to the existing registration of property names, data types, readability, or writeability are allowed.

Returns

public boolean isReturnNull ()

Should this DynaClass return a null from the getDynaProperty(name) method if the property doesn't exist.

Returns
  • true if a null DynaProperty should be returned if the property doesn't exist, otherwise false if a new DynaProperty should be created.

public void remove (String name)

Remove the specified dynamic property, and any associated data type, readability, and writeability, from this dynamic class. NOTE - This does NOT cause any corresponding property values to be removed from DynaBean instances associated with this DynaClass.

Parameters
name Name of the dynamic property to remove
Throws
IllegalArgumentException if name is null
IllegalStateException if this DynaClass is currently restricted, so no properties can be removed

public void setRestricted (boolean restricted)

Set whether this DynaClass is currently restricted.

If restricted, no changes to the existing registration of property names, data types, readability, or writeability are allowed.

Parameters
restricted true if this MutableDynaClass cannot be changed otherwise false

public void setReturnNull (boolean returnNull)

Set whether this DynaClass should return a null from the getDynaProperty(name) method if the property doesn't exist.

Parameters
returnNull true if a null DynaProperty should be returned if the property doesn't exist, otherwise false if a new DynaProperty should be created.

Protected Methods

protected void add (DynaProperty property)

Add a new dynamic property.

Parameters
property Property the new dynamic property to add.
Throws
IllegalArgumentException if name is null
IllegalStateException if this DynaClass is currently restricted, so no new properties can be added