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greenDAO is a light and fast ORM for Android

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/*
 * Copyright (C) 2011-2016 Markus Junginger, greenrobot (http://greenrobot.org)
 *
 * 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 org.greenrobot.greendao.query;

import android.database.Cursor;
import org.greenrobot.greendao.AbstractDao;
import org.greenrobot.greendao.DaoException;

public class CountQuery extends AbstractQuery {

    private final static class QueryData extends AbstractQueryData> {

        private QueryData(AbstractDao dao, String sql, String[] initialValues) {
            super(dao, sql, initialValues);
        }

        @Override
        protected CountQuery createQuery() {
            return new CountQuery(this, dao, sql, initialValues.clone());
        }
    }

    static  CountQuery create(AbstractDao dao, String sql, Object[] initialValues) {
        QueryData queryData = new QueryData(dao, sql, toStringArray(initialValues));
        return queryData.forCurrentThread();
    }

    private final QueryData queryData;

    private CountQuery(QueryData queryData, AbstractDao dao, String sql, String[] initialValues) {
        super(dao, sql, initialValues);
        this.queryData = queryData;
    }

    public CountQuery forCurrentThread() {
        return queryData.forCurrentThread(this);
    }

    /** Returns the count (number of results matching the query). Uses SELECT COUNT (*) sematics. */
    public long count() {
        checkThread();
        Cursor cursor = dao.getDatabase().rawQuery(sql, parameters);
        try {
            if (!cursor.moveToNext()) {
                throw new DaoException("No result for count");
            } else if (!cursor.isLast()) {
                throw new DaoException("Unexpected row count: " + cursor.getCount());
            } else if (cursor.getColumnCount() != 1) {
                throw new DaoException("Unexpected column count: " + cursor.getColumnCount());
            }
            return cursor.getLong(0);
        } finally {
            cursor.close();
        }
    }

}