com.abubusoft.kripton.android.sqlite.PaginatedResult Maven / Gradle / Ivy

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/*******************************************************************************
 * Copyright 2015, 2017 Francesco Benincasa ([email protected]).
 *
 * 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 com.abubusoft.kripton.android.sqlite;

import java.util.List;

/**
 * 
 * Allow to manage SQL result pages with LIMIT clause.
 * 
 * 
 * 
 * See here for more info.
 * 
 *
 * @author Francesco Benincasa ([email protected])
 * @param  the element type
 */
public abstract class PaginatedResult {
	
	/**
	 * Instantiates a new paginated result.
	 */
	protected PaginatedResult()
	{
		initialized=false;
	}
	
	/** The initialized. */
	protected boolean initialized;

	/** The first row. */
	protected int firstRow;

	/** The list. */
	protected List list;

	/** The page size. */
	protected int pageSize;

	/**
	 * Execute.
	 *
	 * @return the list
	 */
	public abstract List execute();

	/**
	 * First row.
	 *
	 * @return the int
	 */
	public int firstRow() {
		return firstRow;
	}

	/**
	 * Next page.
	 *
	 * @return true, if successful
	 */
	public boolean nextPage() {
		if (initialized)
		{
			firstRow += pageSize;
		} else {
			initialized=true;	
		}
		
		return execute().size()>0;
	}

	/**
	 * Goto page.
	 *
	 * @param page the page
	 * @return true, if successful
	 */
	public boolean gotoPage(int page) {
		firstRow = pageSize * page ;
		
		if (firstRow<0) {
			firstRow=0;
			return false;
		}
		
		return execute().size()>0;
	}

	/**
	 * Previous page.
	 *
	 * @return true, if successful
	 */
	public boolean previousPage() {
		firstRow -= pageSize;

		if (firstRow < -1)
			firstRow = -1;
		
		return execute().size()>0;
	}
	
	/**
	 * Checks for next.
	 *
	 * @return true, if successful
	 */
	public boolean hasNext()
	{
		return list.size()>0;
	}

	/**
	 * List.
	 *
	 * @return the list
	 */
	public List list() {
		return list;
	}

	/**
	 * Page size.
	 *
	 * @return the int
	 */
	public int pageSize() {
		return pageSize;
	}
}