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## org.apache.commons.beanutils
Class LazyDynaClass

    java.lang.Object
      |
      +--org.apache.commons.beanutils.BasicDynaClass
            |
            +--org.apache.commons.beanutils.LazyDynaClass

All Implemented Interfaces:
  DynaClass, MutableDynaClass, java.io.Serializable

public class LazyDynaClass
extends BasicDynaClass
implements MutableDynaClass

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.

Author:
  Niall Pemberton
See Also:
  `LazyDynaBean`, Serialized Form

Field Summary
`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.

Fields inherited from class org.apache.commons.beanutils.BasicDynaClass
`constructor, constructorTypes, constructorValues, dynaBeanClass, name, properties, propertiesMap`

Constructor Summary
`LazyDynaClass()` Construct a new LazyDynaClass with default parameters.
`LazyDynaClass(java.lang.String name)` Construct a new LazyDynaClass with the specified name.
`LazyDynaClass(java.lang.String name, java.lang.Class dynaBeanClass)` Construct a new LazyDynaClass with the specified name and DynaBean class.
`LazyDynaClass(java.lang.String name, java.lang.Class dynaBeanClass, DynaProperty[] properties)` Construct a new LazyDynaClass with the specified name, DynaBean class and properties.
`LazyDynaClass(java.lang.String name, DynaProperty[] properties)` Construct a new LazyDynaClass with the specified name and properties.

Method Summary
`protected void` | `add(DynaProperty property)` Add a new dynamic property.
`void` | `add(java.lang.String name)` Add a new dynamic property with no restrictions on data type, readability, or writeability.
`void` | `add(java.lang.String name, java.lang.Class type)` Add a new dynamic property with the specified data type, but with no restrictions on readability or writeability.
`void` | `add(java.lang.String name, java.lang.Class type, boolean readable, boolean writeable)` Add a new dynamic property with the specified data type, readability, and writeability.
`DynaProperty` | `getDynaProperty(java.lang.String name)` Return a property descriptor for the specified property.
`boolean` | `isDynaProperty(java.lang.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(java.lang.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.

Methods inherited from class org.apache.commons.beanutils.BasicDynaClass
`getDynaBeanClass, getDynaProperties, getName, newInstance, setDynaBeanClass, setProperties`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface org.apache.commons.beanutils.DynaClass
`getDynaProperties, getName, newInstance`

Field Detail

### restricted

    protected boolean restricted

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

### returnNull

    protected boolean returnNull

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

  Default is `false`.

Constructor Detail

### LazyDynaClass

    public LazyDynaClass()

  Construct a new LazyDynaClass with default parameters.

### LazyDynaClass

    public LazyDynaClass(java.lang.String name)

  Construct a new LazyDynaClass with the specified name.
  Parameters:
    `name` - Name of this DynaBean class

### LazyDynaClass

    public LazyDynaClass(java.lang.String name,
                         java.lang.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

### LazyDynaClass

    public LazyDynaClass(java.lang.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

### LazyDynaClass

    public LazyDynaClass(java.lang.String name,
                         java.lang.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

Method Detail

### isRestricted

    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.

  Specified by:
    `isRestricted` in interface `MutableDynaClass`
  Returns:
    `true` if this `MutableDynaClass` cannot be changed otherwise `false`

### setRestricted

    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.

  Specified by:
    `setRestricted` in interface `MutableDynaClass`
  Parameters:
    `restricted` - `true` if this `MutableDynaClass` cannot be changed otherwise `false`

### isReturnNull

    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.``

### setReturnNull

    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.``

### add

    public void add(java.lang.String name)

  Add a new dynamic property with no restrictions on data type, readability, or writeability.
  Specified by:
    `add` in interface `MutableDynaClass`
  Parameters:
    `name` - Name of the new dynamic property
  Throws:
    `java.lang.IllegalArgumentException` - if name is null
    `IllegalStateException` - if this DynaClass is currently restricted, so no new properties can be added

### add

    public void add(java.lang.String name,
                    java.lang.Class type)

  Add a new dynamic property with the specified data type, but with no restrictions on readability or writeability.
  Specified by:
    `add` in interface `MutableDynaClass`
  Parameters:
    `name` - Name of the new dynamic property
    `type` - Data type of the new dynamic property (null for no restrictions)
  Throws:
    `java.lang.IllegalArgumentException` - if name is null
    `IllegalStateException` - if this DynaClass is currently restricted, so no new properties can be added

### add

    public void add(java.lang.String name,
                    java.lang.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.

  Specified by:
    `add` in interface `MutableDynaClass`
  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

### add

    protected void add(DynaProperty property)

  Add a new dynamic property.
  Parameters:
    `property` - Property the new dynamic property to add.
  Throws:
    `java.lang.IllegalArgumentException` - if name is null
    `IllegalStateException` - if this DynaClass is currently restricted, so no new properties can be added

### remove

    public void remove(java.lang.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.
  Specified by:
    `remove` in interface `MutableDynaClass`
  Parameters:
    `name` - Name of the dynamic property to remove
  Throws:
    `java.lang.IllegalArgumentException` - if name is null
    `IllegalStateException` - if this DynaClass is currently restricted, so no properties can be removed

### getDynaProperty

    public DynaProperty getDynaProperty(java.lang.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.

  Specified by:
    `getDynaProperty` in interface `DynaClass`
  Overrides:
    `getDynaProperty` in class `BasicDynaClass`
  Parameters:
    `name` - Name of the dynamic property for which a descriptor is requested
  Returns:
    The dyna property for the specified name
  Throws:
    `java.lang.IllegalArgumentException` - if no property name is specified

### isDynaProperty

    public boolean isDynaProperty(java.lang.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:
    `java.lang.IllegalArgumentException` - if no property name is specified

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