com.imminentmeals.android.base.utilities.database.CursorWalker.java Source code

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Here is the source code for com.imminentmeals.android.base.utilities.database.CursorWalker.java

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/*******************************************************************************
 * Copyright (c) 2012, Robotoworks Limited
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 *******************************************************************************/
package com.imminentmeals.android.base.utilities.database;

import android.database.Cursor;

import com.google.common.io.Closeables;

import java.io.IOException;

/**
 * <p>A convenience class to iterate over all the rows in a cursor calling {@link #step(android.database.Cursor)}
 * for each row and finally closing the cursor when no rows are left to walk.</p>
 * <p><b>Example:</b></p>
 *
 * <code><pre>
 * new CursorWalker() {
 *     &#64Override
 *     protected Cursor createCursor() {
 *         return _query_builder.get().select(Books.CONTENT_URI);
 *     }
 *
 *     &#64Override
 *     protected void step(Cursor cursor) {
 *         // TODO do something with each row
 *     }
 * }.walk();
 * </pre></code>
 *
 */
public abstract class CursorWalker {

    /**
     * <p>Creates the {@link android.database.Cursor} to walk.</p>
     * @return the cursor to walk
     */
    protected abstract Cursor createCursor();

    /**
     * <p>Called for each row of the cursor, each time it is called the cursor
     * is moved to the next position until no more rows are left.</p>
     * @param cursor the given cursor
     */
    protected abstract void step(Cursor cursor);

    /**
     * <p>Walks the {@link android.database.Cursor} and performs {@link #step(android.database.Cursor)} on each row.</p>
     * @return number of records in the query
     */
    public int walk() {
        Cursor cursor = null;

        try {
            cursor = createCursor();

            for (int i = 0; i < cursor.getCount(); i++) {
                cursor.moveToNext();
                step(cursor);
            }

            return cursor.getCount();

        } finally {
            //noinspection EmptyCatchBlock
            try {
                Closeables.close(cursor, true);
            } catch (IOException _) {
            }
        }
    }
}