public class

LazyDynaList

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

Class Overview

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);

Summary

[Expand]
Inherited Fields
From class java.util.AbstractList
Public Constructors
LazyDynaList()
Default Constructor.
LazyDynaList(int capacity)
Construct a LazyDynaList with the specified capacity.
LazyDynaList(DynaClass elementDynaClass)
Construct a LazyDynaList with a specified DynaClass for its elements.
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(Object[] array)
Construct a LazyDynaList populated with the elements of an Array.
Public Methods
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.

[Expand]
Inherited Methods
From class java.util.ArrayList
From class java.util.AbstractList
From class java.util.AbstractCollection
From class java.lang.Object
From interface java.lang.Iterable
From interface java.util.Collection
From interface java.util.List

Public Constructors

public LazyDynaList ()

Default Constructor.

public LazyDynaList (int capacity)

Construct a LazyDynaList with the specified capacity.

Parameters
capacity The initial capacity of the list.

public LazyDynaList (DynaClass elementDynaClass)

Construct a LazyDynaList with a specified DynaClass for its elements.

Parameters
elementDynaClass The DynaClass of the List's elements.

public LazyDynaList (Class elementType)

Construct a LazyDynaList with a specified type for its elements.

Parameters
elementType The Type of the List's elements.

public LazyDynaList (Collection collection)

Construct a LazyDynaList populated with the elements of a Collection.

Parameters
collection The Collection to poulate the List from.

public LazyDynaList (Object[] array)

Construct a LazyDynaList populated with the elements of an Array.

Parameters
array The Array to poulate the List from.

Public Methods

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.

Parameters
index The index position to insert the new element.
element The new element to add.

public boolean add (Object element)

Add an element to the List.

Parameters
element The new element to add.
Returns
  • true.

public boolean addAll (Collection collection)

Add all the elements from a Collection to the list.

Parameters
collection The Collection of new elements.
Returns
  • true if elements were added.

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.

Parameters
index The index position to insert the new elements at.
collection The Collection of new elements.
Returns
  • true if elements were added.

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.

Parameters
index The index position to insert the new elements at.
Returns
  • The element at the specified position.

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.

Parameters
index The index position to insert the new element at.
element The new element.
Returns
  • The new element.

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.

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.

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.

Returns
  • An Array of the elements in this List.

public Object[] toArray (Object[] model)

Converts the List to an Array of the specified type.

Parameters
model The model for the type of array to return
Returns
  • An Array of the elements in this List.

public DynaBean[] toDynaBeanArray ()

Converts the List to an DynaBean Array.

Returns
  • A DynaBean[] of the elements in this List.