org.noorganization.instalist.utils.SQLiteUtils.java Source code

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Here is the source code for org.noorganization.instalist.utils.SQLiteUtils.java

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/*
 * Copyright 2016 Tino Siegmund, Michael Wodniok
 *
 * 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.noorganization.instalist.utils;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.annotation.NonNull;
import android.support.v4.util.ArrayMap;

import java.util.Map;
import java.util.UUID;

/**
 * Additional utils and helper functions for sqlite.
 * Created by Tino on 24.10.2015.
 */
public class SQLiteUtils {

    /**
     * The sqlite rowid column.
     */
    public final static String COLUMN_ROW_ID = "rowid";

    /**
     * Prepends a selection-string using a SQL-AND-conjunction.
     *
     * @param _prependedSelection The additional selection.
     * @param _originalSelection  The original selection string. May be null (that means, there was
     *                            no original selection).
     * @return A combined selection string.
     */
    public static String prependSelection(@NonNull String _prependedSelection, String _originalSelection) {
        if (_originalSelection != null) {
            return "(" + _prependedSelection + ") AND (" + _originalSelection + ")";
        } else {
            return _prependedSelection;
        }
    }

    /**
     * Alias for {@link #prependSelectionArgs(String[], String[])}. But for only one additional
     * argument for better readable code.
     *
     * @see #prependSelectionArgs(String[], String[])
     */
    public static String[] prependSelectionArgs(@NonNull String _prependedSelectionArg,
            String[] _originalSelectionArgs) {
        return prependSelectionArgs(new String[] { _prependedSelectionArg }, _originalSelectionArgs);
    }

    /**
     * Prepends selection args.
     *
     * @param _prependedSelectionArgs The new selection-arguments to prepend.
     * @param _originalSelectionArgs  The previous selection-arguments. May be null.
     * @return The combined array of selection arguments. If _originalSelectionArgs are null,
     * _prependedSelectionArgs get returned.
     */
    public static String[] prependSelectionArgs(@NonNull String[] _prependedSelectionArgs,
            String[] _originalSelectionArgs) {
        if (_originalSelectionArgs == null || _originalSelectionArgs.length == 0) {
            return _prependedSelectionArgs;
        }

        int newArrayLength = _prependedSelectionArgs.length + _originalSelectionArgs.length;
        String[] rtn = new String[newArrayLength];
        System.arraycopy(_prependedSelectionArgs, 0, rtn, 0, _prependedSelectionArgs.length);
        System.arraycopy(_originalSelectionArgs, 0, rtn, _prependedSelectionArgs.length,
                _originalSelectionArgs.length);
        return rtn;
    }

    /**
     * Generate a column map for usage with
     * {@link android.database.sqlite.SQLiteQueryBuilder#setProjectionMap(Map)}.
     *
     * @param _table  The table to generate the map for. The table is not checked for existence but
     *                must not be empty.
     * @param _column As many columns as needed. May not be empty.
     * @return A Map containing all given columns projection-maps.
     */
    public static Map<String, String> generateProjectionMap(@NonNull String _table, String... _column) {
        Map<String, String> rtn = new ArrayMap<>(_column.length);
        for (String currentColumn : _column) {
            rtn.put(currentColumn, _table + "." + currentColumn);
        }
        return rtn;
    }

    /**
     * Generates for the table in the given database a unique id.
     *
     * @param _db    the database where the table is.
     * @param _table the table to get the uuid for.
     * @return a really unique id.
     */
    public static UUID generateId(SQLiteDatabase _db, String _table) {
        UUID rtn = null;
        while (rtn == null) {
            rtn = UUID.randomUUID();
            Cursor counter = _db.query(_table, new String[] { "_id" }, "_id = ?", new String[] { rtn.toString() },
                    null, null, null);
            if (counter.getCount() != 0) {
                rtn = null;
            }
            counter.close();
        }
        return rtn;
    }

    /**
     * Generates for the table in the given database a unique id for the specified column.
     *
     * @param _db     the database where the table is.
     * @param _table  the table to get the uuid for.
     * @param _column the column where the value should be unique.
     * @return a really unique id.
     */
    public static UUID generateId(SQLiteDatabase _db, String _table, String _column) {
        UUID rtn = null;
        while (rtn == null) {
            rtn = UUID.randomUUID();
            Cursor counter = _db.query(_table, new String[] { _column }, _column + " = ?",
                    new String[] { rtn.toString() }, null, null, null);
            if (counter.getCount() != 0) {
                rtn = null;
            }
            counter.close();
        }
        return rtn;
    }
}