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License

The source code is released under:

Apache License

Java Source Code

package com.clearblade.platform.api;
/*  w w  w  .  jav  a  2 s.  com*/
import java.util.Iterator;


/**
 * This class consists exclusively of instance methods that operate on ClearBlade Collections.
 * <p>
 * ClearBlade Collections are objects that can query Cloud backend collections for Items.
 * A typical example would be:
 * <pre> 
 *     Collection collection = new Collection(collectionId);
 *    collection.fetchAll(new DataCallback(){
 *
 *      @Override
 *      public void done(QueryResponse resp) {
 *        String msg = "";
 *        for (int i=0;i<resp.getDataItems().length;i++){
 *          msg = msg + resp.getDataItems()[i].toString()+",";
 *        }  
 *      }
 *
 *      @Override
 *      public void error(ClearBladeException exception) {
 *        // TODO Auto-generated method stub        
 *      }
 *    });
 * </pre>
 * </p>
 *
 * @author  Clyde Byrd, Aaron Allsbrook
 * @see Item
 * @see Query
 * @see ClearBladeException
 * @since   1.0
 * 
 */
public class Collection implements Iterable<Item>{

  private class ArrayIterator implements Iterator<Item> {
    // since itemArray.length is N, we decrement it immediately to N - 1 in next()
    private int i = itemArray.length; 
  
    public boolean hasNext() { return i > 0;}
    public Item next() { return itemArray[--i];} 
    public void remove() {
      throw new UnsupportedOperationException("remove is not supported.");
    }
  }
  private final String TAG = "CLEARBLADECOLLECTION";
  private String collectionId;      // Type of collection
  private Query query;      // string to filter data by
  private Item[] itemArray;    // array that stores all Items

  //private RequestEngine request;  // used to make API requests

  /**
   * Constructs a new ClearBladeCollection of the specified type
   * 
   * @param id the Id of the Collection
   */
  public Collection(String id) {
    this.collectionId = id;
    this.query = null;
    //this.request = new RequestEngine();
    this.itemArray = null;
  }
  
  /** 
   * Deletes all Items that are saved in the collection in the Cloud synchronously.
   * <p>Deleted Items will be stored locally in the Collection.</p>
   * <strong>*Overrides previously stored Items*</strong>
   * <strong>*Runs in its own asynchronous task*</strong>
   * @throws ClearBladeException will be returned in the callback error function
   */
  public void clear(DataCallback callback) {
    Query query = new Query(collectionId);
    query.remove(callback);
  }

  /**
   * Returns all items in the collection as item[].
   * @private
   * @param json A JSON Array in string format
   * @return Item[] An array of Items
   * @throws ClearBladeException will be thrown if Collection was Empty!
   */
  public Item[] getItems(){
    return itemArray;
  }
//  private Item[] convertJsonArrayToItemArray(String json) {
//    // Parse the JSON string in to a JsonElement
//    JsonElement jsonArrayString = new JsonParser().parse(json);
//    // Store the JsonElement as a JsonArray
//    JsonArray array = jsonArrayString.getAsJsonArray();
//    // If array size is 0, the Collection was empty; Throw Error
//    if(array.size() == 0) {
//    //  throw new ClearBladeException("Collection was Empty!");
//    }
//    
//    // Create Item Array and initialize its values
//    Item[] items = new Item[array.size()];
//    
//    for(int i = 0, len = array.size(); i < len; i++){
//      items[i] = new Item(array.get(i).getAsJsonObject().toString(), this.id);
//    }
//    
//    return items;
//  }

  
  /** 
   * Gets all Items that match Query criteria from the platform in the Cloud.
   * <p>Retrieved Items will be stored locally in the Collection.</p>
   * <strong>*Overrides previously stored Items*</strong>
   * <strong>*Runs in its own asynchronous task*</strong>
   * @throws ClearBladeException will be returned in callback.error() if the collection was empty
   */
  public void fetch(Query query, final DataCallback callback) {
  
    query.setCollectionId(collectionId);
    query.fetch(new DataCallback(){

      @Override
      public void done(QueryResponse response) {
        itemArray = response.getDataItems();
        callback.done(response);
      }

      @Override
      public void error(ClearBladeException exception) {
        callback.error(exception);
      }
      
    });
  }
  
  /** 
   * Gets all Items that match Query criteria from the platform in the Cloud.
   * <p>Retrieved Items will be stored locally in the Collection.</p>
   * <strong>*Overrides previously stored Items*</strong>
   * <strong>*Runs in its own asynchronous task*</strong>
   * @throws ClearBladeException will be returned in callback.error() if the collection was empty
   */
  public void fetch(final DataCallback callback) {
    fetch(query, callback);
  }
  
  /** 
   * Gets all Items that are saved in the collection in the Cloud.
   * <p>Retrieved Items will be stored locally in the Collection.</p>
   * <strong>*Overrides previously stored Items*</strong>
   * <strong>*Runs in its own asynchronous task*</strong>
   * @throws ClearBladeException will be returned in callback.error() if the collection was empty
   */
  public void fetchAll(final DataCallback callback) {
    Query query = new Query(collectionId);
    query.fetch(new DataCallback(){

      @Override
      public void done(QueryResponse response) {
        itemArray = response.getDataItems();
        callback.done(response);
      }

      @Override
      public void error(ClearBladeException exception) {
        callback.error(exception);
      }
      
    });
  }
  
  public Item[] fetchAllSync() throws ClearBladeException{
    Query query = new Query(collectionId);
  
    return query.fetchSync();
  }

  /**
   * Returns the query to be performed during a call to ClearBladeCollection.fetch(). 
   * will be null if not set by setQuery().
   * @return query The conditional query to perform on a Cloud Collection
   */
  public Query getQuery() {
    return this.query;
  }

  /**
   * Returns an Item Iterator for the ClearBladeC ollection.
   * <p>Will point at the first Item in the collection that is retrieved from a ClearBladeCollection.fetch() or ClearBladeCollection.clear(). </p>
   * @throws RuntimeException will be thrown if a call to ClearBladeCollection.fetch() or ClearBladeCollection.clear() has not been made 
   */
  @Override
  public Iterator<Item> iterator() {
    // If itemArray is null; Throw a ClearBladeException
    if(itemArray == null){
      throw new RuntimeException("You can not Iterate over an Empty Collection");
    }
    return new ArrayIterator();

  }

  /**
   * Sets the query to be performed during a call to ClearBladeCollection.get()
   * @param query A conditional String that will determine what Items to retrieve from the Cloud Database
   */
  public void setQuery(Query query) {
    this.query = query;
  }
  

  /**
   * Helper method for debugging collection contents
   */
  public String toString() {
    String ret = "";
    Iterator<Item> iter = iterator();
    
    while (iter.hasNext()){
      Item temp = iter.next();
      ret = ret + temp.toString();
    }
    return ret;
  }
  
}

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