org.apache.commons.beanutils
Class LazyDynaList

java.lang.Object
  java.util.AbstractCollection
      java.util.AbstractList
          java.util.ArrayList
              org.apache.commons.beanutils.LazyDynaList

All Implemented Interfaces:

Serializable, Cloneable, Iterable, Collection, List, RandomAccess

public class LazyDynaList
extends ArrayList

Lazy DynaBean List.

There are two main purposes for this class:

• To provide Lazy List behaviour - automatically growing and populating the List with either DynaBean, java.util.Map or POJO Beans.
• To provide a straight forward way of putting a Collection or Array into the lazy list and a straight forward way to get it out again at the end.

All elements added to the List are stored as DynaBean's:

• java.util.Map elements are "wrapped" in a LazyDynaMap.
• POJO Bean elements are "wrapped" in a WrapDynaBean.
• DynaBean's are stored un-changed.

toArray()

The toArray() method returns an array of the elements of the appropriate type. If the LazyDynaList is populated with java.util.Map objects a Map[] array is returned. If the list is populated with POJO Beans an appropriate array of the POJO Beans is returned. Otherwise a DynaBean[] array is returned.

toDynaBeanArray()

The toDynaBeanArray() method returns a DynaBean[] array of the elements in the List.

N.B.All the elements in the List must be the same type. If the DynaClass or Class of the LazyDynaList's elements is not specified, then it will be automatically set to the type of the first element populated.

Example 1

If you have an array of java.util.Map[] - you can put that into a LazyDynaList.

    TreeMap[] myArray = .... // your Map[]
    List lazyList = new LazyDynaList(myArray);
 

New elements of the appropriate Map type are automatically populated:

    // get(index) automatically grows the list
    DynaBean newElement = (DynaBean)lazyList.get(lazyList.size());
    newElement.put("someProperty", "someValue");
 

Once you've finished you can get back an Array of the elements of the appropriate type:

    // Retrieve the array from the list
    TreeMap[] myArray = (TreeMap[])lazyList.toArray());
 

Example 2

Alternatively you can create an empty List and specify the Class for List's elements. The LazyDynaList uses the Class to automatically populate elements:

    // e.g. For Maps
    List lazyList = new LazyDynaList(TreeMap.class);
 
    // e.g. For POJO Beans
    List lazyList = new LazyDynaList(MyPojo.class);
 
    // e.g. For DynaBeans
    List lazyList = new LazyDynaList(MyDynaBean.class);
 

Example 3

Alternatively you can create an empty List and specify the DynaClass for List's elements. The LazyDynaList uses the DynaClass to automatically populate elements:

    // e.g. For Maps
    DynaClass dynaClass = new LazyDynaMap(new HashMap());
    List lazyList = new LazyDynaList(dynaClass);
 
    // e.g. For POJO Beans
    DynaClass dynaClass = (new WrapDynaBean(myPojo)).getDynaClass();
    List lazyList = new LazyDynaList(dynaClass);
 
    // e.g. For DynaBeans
    DynaClass dynaClass = new BasicDynaClass(properties);
    List lazyList = new LazyDynaList(dynaClass);
 

N.B. You may wonder why control the type using a DynaClass rather than the Class as in the previous example - the reason is that some DynaBean implementations don't have a default empty constructor and therefore need to be instantiated using the DynaClass.newInstance() method.

Example 4

A slight variation - set the element type using either the setElementType(Class) method or the setElementDynaClass(DynaClass) method - then populate with the normal java.util.List methods(i.e. add(), addAll() or set()).

    // Create a new LazyDynaList (100 element capacity)
    LazyDynaList lazyList = new LazyDynaList(100);
 
    // Either Set the element type...
    lazyList.setElementType(TreeMap.class);
 
    // ...or the element DynaClass...
    lazyList.setElementDynaClass(new MyCustomDynaClass());
 
    // Populate from a collection
    lazyList.addAll(myCollection);

 

Since:

1.8.0

Version:

$Revision: 800638 $ $Date: 2009-08-04 01:23:41 +0100 (Tue, 04 Aug 2009) $

Author:

Niall Pemberton

See Also:

Serialized Form

Field Summary

Fields inherited from class java.util.AbstractList

modCount

Constructor Summary

LazyDynaList()
Default Constructor.

LazyDynaList(Class elementType)
Construct a LazyDynaList with a specified type for its elements.

LazyDynaList(Collection collection)
Construct a LazyDynaList populated with the elements of a Collection.

LazyDynaList(DynaClass elementDynaClass)
Construct a LazyDynaList with a specified DynaClass for its elements.

LazyDynaList(int capacity)
Construct a LazyDynaList with the specified capacity.

LazyDynaList(Object[] array)
Construct a LazyDynaList populated with the elements of an Array.

Method Summary

void	add(int index, Object element) Insert an element at the specified index position.
boolean	add(Object element) Add an element to the List.
boolean	addAll(Collection collection) Add all the elements from a Collection to the list.
boolean	addAll(int index, Collection collection) Insert all the elements from a Collection into the list at a specified position.
Object	get(int index) Return the element at the specified position.
Object	set(int index, Object element) Set the element at the specified position.
void	setElementDynaClass(DynaClass elementDynaClass) Set the element Type and DynaClass.
void	setElementType(Class elementType) Set the element Type and DynaClass.
Object[]	toArray() Converts the List to an Array.
Object[]	toArray(Object[] model) Converts the List to an Array of the specified type.
DynaBean[]	toDynaBeanArray() Converts the List to an DynaBean Array.

Methods inherited from class java.util.ArrayList

clear, clone, contains, ensureCapacity, indexOf, isEmpty, lastIndexOf, remove, remove, removeRange, size, trimToSize

Methods inherited from class java.util.AbstractList

equals, hashCode, iterator, listIterator, listIterator, subList

Methods inherited from class java.util.AbstractCollection

containsAll, removeAll, retainAll, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.List

containsAll, equals, hashCode, iterator, listIterator, listIterator, removeAll, retainAll, subList

Constructor Detail

LazyDynaList

public LazyDynaList()

Default Constructor.

LazyDynaList

public LazyDynaList(int capacity)

Construct a LazyDynaList with the specified capacity.

Parameters:

capacity - The initial capacity of the list.

LazyDynaList

public LazyDynaList(DynaClass elementDynaClass)

Construct a LazyDynaList with a specified DynaClass for its elements.

Parameters:

elementDynaClass - The DynaClass of the List's elements.

LazyDynaList

public LazyDynaList(Class elementType)

Construct a LazyDynaList with a specified type for its elements.

Parameters:

elementType - The Type of the List's elements.

LazyDynaList

public LazyDynaList(Collection collection)

Construct a LazyDynaList populated with the elements of a Collection.

Parameters:

collection - The Collection to poulate the List from.

LazyDynaList

public LazyDynaList(Object[] array)

Construct a LazyDynaList populated with the elements of an Array.

Parameters:

array - The Array to poulate the List from.

Method Detail

add

public void add(int index,
                Object element)

Insert an element at the specified index position.

If the index position is greater than the current size of the List, then the List is automatically grown to the appropriate size.

Specified by:

add in interface List

Overrides:

add in class ArrayList

Parameters:

index - The index position to insert the new element.

element - The new element to add.

add

public boolean add(Object element)

Add an element to the List.

Specified by:

add in interface Collection

Specified by:

add in interface List

Overrides:

add in class ArrayList

Parameters:

element - The new element to add.

Returns:

true.

addAll

public boolean addAll(Collection collection)

Add all the elements from a Collection to the list.

Specified by:

addAll in interface Collection

Specified by:

addAll in interface List

Overrides:

addAll in class ArrayList

Parameters:

collection - The Collection of new elements.

Returns:

true if elements were added.

addAll

public boolean addAll(int index,
                      Collection collection)

Insert all the elements from a Collection into the list at a specified position.

If the index position is greater than the current size of the List, then the List is automatically grown to the appropriate size.

Specified by:

addAll in interface List

Overrides:

addAll in class ArrayList

Parameters:

collection - The Collection of new elements.

index - The index position to insert the new elements at.

Returns:

true if elements were added.

get

public Object get(int index)

Return the element at the specified position.

If the position requested is greater than the current size of the List, then the List is automatically grown (and populated) to the appropriate size.

Specified by:

get in interface List

Overrides:

get in class ArrayList

Parameters:

index - The index position to insert the new elements at.

Returns:

The element at the specified position.

set

public Object set(int index,
                  Object element)

Set the element at the specified position.

If the position requested is greater than the current size of the List, then the List is automatically grown (and populated) to the appropriate size.

Specified by:

set in interface List

Overrides:

set in class ArrayList

Parameters:

index - The index position to insert the new element at.

element - The new element.

Returns:

The new element.

toArray

public Object[] toArray()

Converts the List to an Array.

The type of Array created depends on the contents of the List:

• If the List contains only LazyDynaMap type elements then a java.util.Map[] array will be created.
• If the List contains only elements which are "wrapped" DynaBeans then an Object[] of the most suitable type will be created.
• ...otherwise a DynaBean[] will be created.

Specified by:

toArray in interface Collection

Specified by:

toArray in interface List

Overrides:

toArray in class ArrayList

Returns:

An Array of the elements in this List.

toArray

public Object[] toArray(Object[] model)

Converts the List to an Array of the specified type.

Specified by:

toArray in interface Collection

Specified by:

toArray in interface List

Overrides:

toArray in class ArrayList

Parameters:

model - The model for the type of array to return

Returns:

An Array of the elements in this List.

toDynaBeanArray

public DynaBean[] toDynaBeanArray()

Converts the List to an DynaBean Array.

Returns:

A DynaBean[] of the elements in this List.

setElementType

public void setElementType(Class elementType)

Set the element Type and DynaClass.

Parameters:

elementType - The type of the elements.

Throws:

IllegalArgumentException - if the List already contains elements or the DynaClass is null.

setElementDynaClass

public void setElementDynaClass(DynaClass elementDynaClass)

Set the element Type and DynaClass.

Parameters:

elementDynaClass - The DynaClass of the elements.

Throws:

IllegalArgumentException - if the List already contains elements or the DynaClass is null.