Android Open Source - InMemoryDb In Memory Db Set

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License

The source code is released under:

Apache License

Java Source Code

package org.gawst.asyncdb;
/*  ww  w  .  java2  s  . co  m*/
import android.content.ContentValues;
import android.database.Cursor;

import org.gawst.asyncdb.adapter.InMemoryFilteredAdapter;

import java.lang.ref.WeakReference;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

/**
 * a basic helper class to keep the content of a flat database in an {@link List}
 * @author Steve Lhomme
 *
 * @param <E> the type of items stored in memory by the {@link InMemoryDbSet}
 * @param <S> the type of in memory storage that will be used
 */
public abstract class InMemoryDbSet<E, S extends Set<E>, INSERT_ID> extends AsynchronousDbHelper<E, INSERT_ID> implements AsynchronousDbErrorHandler<E>, InMemoryFilteredAdapter.InMemoryFilter.InMemoryFilterable<E>/*, Set<E>*/ {

  private WeakReference<AsynchronousDbErrorHandler<E>> mListener;

  /**
   * @param db The already created {@link android.database.sqlite.SQLiteOpenHelper} to use as storage
   * @param name Database name for logs
   * @param logger The {@link org.gawst.asyncdb.Logger} to use for all logs (can be null for the default Android logs)
   * @param initCookie Cookie to pass to {@link AsynchronousDbHelper#preloadInit(Object)}
   */
  protected InMemoryDbSet(DataSource<E, INSERT_ID> db, String name, Logger logger, Object initCookie) {
    super(db, name, logger, initCookie);
    super.setDbErrorHandler(this);
  }

  /**
   * return the object used to the in-memory elements
   * @return
   */
  abstract protected S getSet();

  /**
   * transform the {@link Cursor} into an element that can be used in memory
   * @param c the Cursor to transform
   * @return a formated element used in memory
   * @see AsynchronousDbHelper#getValuesFromData(Object)
   */
  protected abstract E getDataFromCursor(Cursor c);

  protected void onDataCleared() {}

  @Override
  public void setDbErrorHandler(AsynchronousDbErrorHandler<E> listener) {
    if (listener==null)
      mListener = null;
    else
      mListener = new WeakReference<AsynchronousDbErrorHandler<E>>(listener);
  }

  @Override
  public final void addItemInMemory(E item) {
    getSet().add(item);
  }

  /**
   * add a new element in memory (synchronous) and in the database (asynchronous)
   * @param item to add
   */
  public boolean add(E item) {
    if (getSet().add(item)) {
      scheduleAddOperation(item);
      return true;
    }
    return false;
  }
  
  /**
   * replace an existing element by the same element with other values not included in {@link E#equals(Object)}
   * @param item
   * @return true if the element was replaced
   */
  public boolean replace(E item) {
    if (!getSet().contains(item))
      return false;
    getSet().remove(item);
    getSet().add(item);
    scheduleUpdateOperation(item);
    return true;
  }
  
  /**
   * remove and item from memory (synchronous) and from the database (asynchronous)
   * @param item
   * @return true if the element was removed
   */
  public boolean remove(E item) {
    if (!getSet().remove(item))
      return false;

    scheduleRemoveOperation(item);
    return true;
  }

  public boolean removeAll(Collection<E> collection) {
    if (!getSet().removeAll(collection))
      return false;
    pushModifyingTransaction();
    for (E e : collection)
      scheduleRemoveOperation(e);
    popModifyingTransaction();
    return true;
  }

  public boolean contains(E object) {
    return getSet().contains(object);
  }

  public E get(int position) {
    if (position >= getSet().size())
      return null;
    Iterator<E> it = getSet().iterator();
    while (position-- > 0 && it.hasNext())
      it.next();
    return it.next();
  }

  @Override
  protected void clearDataInMemory() {
    getSet().clear();
    super.clearDataInMemory();
    onDataCleared();
  }

  public void onAddItemFailed(AsynchronousDbHelper<E, ?> db, E item, ContentValues values, Throwable cause) {
    // revert the failed change in memory
    remove(item);

    if (mListener!=null) {
      final AsynchronousDbErrorHandler<E> listener = mListener.get();
      if (listener==null)
        mListener = null;
      else
        listener.onAddItemFailed(db, item, values, cause);
    }
  }

  public void onRemoveItemFailed(AsynchronousDbHelper<E, ?> db, E item, Throwable cause) {
    // revert the failed change in memory
    add(item);

    if (mListener!=null) {
      final AsynchronousDbErrorHandler<E> listener = mListener.get();
      if (listener==null)
        mListener = null;
      else
        listener.onRemoveItemFailed(db, item, cause);
    }
  }

  public void onUpdateItemFailed(AsynchronousDbHelper<E, ?> db, E item, Throwable cause) {
    if (mListener!=null) {
      final AsynchronousDbErrorHandler<E> listener = mListener.get();
      if (listener==null)
        mListener = null;
      else
        listener.onUpdateItemFailed(db, item, cause);
    }
  }

  public void onReplaceItemFailed(AsynchronousDbHelper<E, ?> db, E original, E replacement, Throwable cause) {
    // do nothing
  }
  
  @Override
  public void onCorruption(AsynchronousDbHelper<E, ?> db) {
    if (mListener!=null) {
      final AsynchronousDbErrorHandler<E> listener = mListener.get();
      if (listener==null)
        mListener = null;
      else
        listener.onCorruption(db);
    }
  }
}

Java Source Code List

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