oracle.iot.client.enterprise

Interface Pageable<T>

public interface Pageable<T>

A Pageable instance is a cached view on a remote collection of elements of the specified type T.

Notion of Pages

The remote collection is not entirely loaded in memory but only a subset of the elements is loaded in the cache. This subset is called a page and has a configurable limit and offset to respectively control the maximum number of elements to fetch from the remote collection and the absolute offset of the first element to fetch. The elements loaded in the cache are accessed using elements().

Navigation

The Pageable instance is also used to navigate in the remote collection and access its elements. The navigation supports random access to any position in the remote collection and is performed by calling one of the following methods: next(), first(), last(), at(int offset). Navigation implies accessing the remote collection and may fail with an I/O error.

Concurrent modifications of the remote collection

The remote collection might be modified concurrently. Consequences:

• Changes that occurred in the remote collection are not reflected in the elements in the cache accessed with elements()
• The total size of the collection might have evolved since last access and may affect the result of next(), at(int) and last()

Examples:

     Pageable<String> p;

     // iterate on all elements of the remote collection
     while (p.hasMore()) {
         // get next available page, using already initialized offset and limit
         p = p.next();

         // get the elements of the first page
         Collection<String> names = p.elements();
         ...

     }

     // get 10 elements, starting at offset 300 in the remote collection.
     Collection<String> names = p.limit(10).at(300).elements();
 

Method Summary

Modifier and Type	Method and Description
Pageable<T>	at(int offset) Navigate to the specified offset in the remote collection and return the corresponding page
java.util.Collection<T>	elements() Returns the subset of elements that have been loaded from the remote collection.
Pageable<T>	first() Navigate to the first page and return a view on it.
boolean	hasMore() Returns whether or not more elements are available in the remote collection, accessible using next().
Pageable<T>	last() Navigate to the last page and return a view on it.
int	limit() Get the maximum number of elements that will be fetched from the remote collection during next refill.
Pageable<T>	limit(int limit) Set the number of elements that will be retrieved from the remote collection during next refill.
Pageable<T>	next() Navigate in the remote collection to get the next page, starting at the specified offset increased by the number of elements of the current page, and return a view on it.
int	offset() Get the absolute offset in the remote collection of the first element.
int	size() Get the total number of elements in the collection

Method Detail

size

int size()

Get the total number of elements in the collection

Returns:

the size of the collection

hasMore

boolean hasMore()

Returns whether or not more elements are available in the remote collection, accessible using next().

Returns:

true if more elements are available.

offset

int offset()

Get the absolute offset in the remote collection of the first element.

Returns:

the offset of the first element

limit

int limit()

Get the maximum number of elements that will be fetched from the remote collection during next refill.

Returns:

the maximum number of elements to fetch

limit

Pageable<T> limit(int limit)

Set the number of elements that will be retrieved from the remote collection during next refill.

Parameters:

limit - the maximum number of elements of a page

Returns:

Pageable instance configured with the new limit (could be the same object).

elements

java.util.Collection<T> elements()

Returns the subset of elements that have been loaded from the remote collection.

Returns:

the elements of current page.

next

Pageable<T> next()
          throws java.io.IOException,
                 java.util.NoSuchElementException

Navigate in the remote collection to get the next page, starting at the specified offset increased by the number of elements of the current page, and return a view on it.

Returns:

the next page in the remote collection

Throws:

java.io.IOException - if an I/O error occurred while trying to access remote collection

java.util.NoSuchElementException - if the collection has no more element

See Also:

hasMore()

first

Pageable<T> first()
           throws java.io.IOException

Navigate to the first page and return a view on it.

Returns:

the first page in the remote collection

Throws:

java.io.IOException - if an I/O error occurred while trying to access remote collection

last

Pageable<T> last()
          throws java.io.IOException

Navigate to the last page and return a view on it.

Returns:

the last page in the remote collection

Throws:

java.io.IOException - if an I/O error occurred while trying to access remote collection

at

Pageable<T> at(int offset)
        throws java.io.IOException,
               java.lang.IndexOutOfBoundsException

Navigate to the specified offset in the remote collection and return the corresponding page

Parameters:

offset - the absolute offset of the first element to fetch

Returns:

an Pageable to access elements of the page

Throws:

java.io.IOException - if an I/O error occurred while trying to access remote collection

java.lang.IndexOutOfBoundsException - if the offset is out of range (offset < 0 || offset >= size())