LocalItemManager.java

/*
 * Copyright (c) 2016 Ha Duy Trung
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.github.hidroh.materialistic.data;

import android.content.Context;
import android.support.v4.app.LoaderManager;

/**
 * Data repository for local items
 * @param <T>    item type
 */
public interface LocalItemManager<T> {
    /**
     * Gets number of items
     * @return  number of items, 0 if none
     */
    int getSize();

    /**
     * Gets item at given position
     * @param position  item position
     * @return  item at given position, or null if none
     */
    T getItem(int position);

    /**
     * Initiates an async query for local items
     * @param context          resources provider
     * @param loaderManager    loader manager
     * @param observer         listener that will be informed on changes
     * @param filter           query filter if any
     */
    void attach(Context context, LoaderManager loaderManager, Observer observer, String filter);

    /**
     * Cleans up any extra state created by {@link #attach(Context, LoaderManager, Observer, String)}
     */
    void detach();

    /**
     * Callback interface for local items change events
     */
    interface Observer {
        /**
         * Fired when local items change (added/removed/edited)
         */
        void onChanged();
    }
}