Question

我有一个使用多个数据库的应用。目前，我只遇到其中一个问题。它在数据库中存储日历的事件。它的SQLiteOpenHelper如下所示：

public class PlanSQLiteHelper extends SQLiteOpenHelper {

//The database version.
public static final int VERSION = 1;

//The String keys of the database name and columns.
public static final String DB_NAME = "plans_db.sqlite";
public static final String PLANS_TABLE = "plans";
public static final String PLAN_ID = "id";
public static final String PLAN_NAME = "name";
public static final String PLAN_YEAR = "year";
public static final String PLAN_MONTH = "month";
public static final String PLAN_DAY = "day";
public static final String PLAN_PRIORITY = "priority";
public static final String PLAN_TIME = "time";
public static final String PLAN_END = "end";
public static final String SET_APPT = "set_appt";
public static final String PLAN_ALARM = "alarm";


public PlanSQLiteHelper(Context context) {
    super(context, DB_NAME, null, VERSION);
}

@Override
public void onCreate(SQLiteDatabase db) {
    createTable(db);
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { }

private void createTable(SQLiteDatabase db) {

    db.execSQL(
            "create table " + PLANS_TABLE + " ( " +
            PLAN_ID + " integer primary key autoincrement not null, " +
            PLAN_NAME + " text, " +
            PLAN_YEAR + " integer, " +
            PLAN_MONTH + " integer, " +
            PLAN_DAY + " integer, " +
            PLAN_PRIORITY + " integer, " +
            PLAN_TIME + " integer, " +
            PLAN_END + " integer, " +
            SET_APPT + " integer, " +
            PLAN_ALARM + " integer );" );
}
}

这是一个过程：用户进入屏幕以创建新的日历项（称为PlanItem）。它有一些选项，他们选择他们想要的选项，然后点击“确定”。制作PlanItem并将其传递给应用程序的Application类中的方法，如下所示：

/**
 * Called to save a PlanItem to the SQLiteDatabase.
 * @param item = the item to save to the database.
 * @param newItem = true if the item is new, false if it exists but was edited.
 * @return true if successful, false otherwise.
 */
public boolean savePlanItem(PlanItem item, boolean newItem) {

    try {

        //Create the ContentValues.
        ContentValues values = new ContentValues();

        //Put the values in.
        values.put(PLAN_NAME, item.getName());
        values.put(PLAN_YEAR, item.getYear());
        values.put(PLAN_MONTH, item.getMonth());
        values.put(PLAN_DAY, item.getDay());
        values.put(PLAN_TIME, item.getTime());
        values.put(PLAN_END, item.getEnd());
        values.put(SET_APPT, item.isSetAppt() ? 1 : 0);
        values.put(PLAN_PRIORITY, item.getPriorityInt());
        values.put(PLAN_ALARM, item.isAlarm() ? 1 : 0);

        if (newItem) {

            //Put into the database.
            long id = plansDatabase.insert(PLANS_TABLE, null, values);

            if (id == -1) {
                return false;
            }
        }
        else {

            //Update the database.
            String where = String.format("%s = ?", PLAN_ID);
            plansDatabase.update(PLANS_TABLE, values, where, new String[] { item.getId() + "" });
        }

    }
    catch (Exception e) {
        return false;
    }

    //Since it succeeded, return true.
    return true;
}

布尔newItem只是告诉方法是否创建或编辑了项目。我的问题在于创作。如您所见，它使用SQLiteDatabase.insert（）方法。我甚至抓住新行的id并将其测试为-1（如果根据Android文档存在错误，则返回-1）。即便如此，该方法返回true，这意味着它正确保存。然后，只要保存，允许用户创建项目的Activity就会完成并返回显示它的Activity。在onResume（）中，它调用Application类来获取当天的PlanItems。它看起来像：

/**
 * Called to get the agenda items for a particular day.
 * @param date = the date to get agenda items for.
 * @return the ArrayList of PlanItems for the day.
 */
public ArrayList<PlanItem> getDailyAgenda(Date d) {

    //Make a new date.
    Date date = new Date(d.getDay(), d.getMonth(), d.getYear());

    //Create the ArrayList.
    ArrayList<PlanItem> items = new ArrayList<PlanItem>();

    //Set up a query.
    Cursor cursor = plansDatabase.query(PLANS_TABLE, new String[] {PLAN_ID, PLAN_NAME, PLAN_YEAR,
            PLAN_MONTH, PLAN_DAY, PLAN_PRIORITY, PLAN_TIME, PLAN_END, SET_APPT, PLAN_ALARM},
            String.format(" %s = ? AND %s = ? AND %s = ? ", PLAN_YEAR, PLAN_MONTH, PLAN_DAY),
            new String[] {String.valueOf(date.getYear()), String.valueOf(date.getMonth()),
            String.valueOf(date.getDay())}, null, null, null);

    //Move the cursor to the first position.
    cursor.moveToFirst();

    //If there are items...
    if (!cursor.isAfterLast()) {

        //Initialize variables.
        long id;
        String name;
        int year, month, day, time, end, priority;
        boolean setAppt, alarm;
        PlanItem item;


        //Go through the database and get everything.
        do {

            //Get the values.
            id = cursor.getLong(0);
            name = cursor.getString(1);
            year = cursor.getInt(2);
            month = cursor.getInt(3);
            day = cursor.getInt(4);
            priority = cursor.getInt(5);
            time = cursor.getInt(6);
            end = cursor.getInt(7);
            setAppt = cursor.getInt(8) == 1;
            alarm = cursor.getInt(9) == 1;

            //Create a PlanItem and add it to the ArrayList.
            item = new PlanItem(id, name, year, month, day,
                    priority, time, end, setAppt, alarm);
            items.add(item);

        } while (cursor.moveToNext());
    }

    //Close the cursor.
    cursor.close();

    //Return the items.
    return items;
}

对象日期是我自己的对象，而不是Java对象。它只包含我需要的方法。

我已在调试器中检查并重新检查查询。它遵循SQLite规则。但是，即使在我创建当天的新项目之后，它也没有从数据库中提取任何内容。它到达return items;行并返回一个空的ArrayList。我走过了周围的日子，看看这个项目是否只是在错误的一天存储，但事实并非如此。我还检查了将哪些日，月和年插入数据库。他们是对的。

我来到stackoverflow并找不到答案。

我无法想象我的生活。请帮忙。

由于这是我的第一个问题，所以对如何改进我的问题的任何评论都表示赞赏。

Answer 1

您应该尝试在savePlanItem（）函数中记录异常，以确保插入完成。

只是一个问题，你在哪里打开这些功能的数据库？

Answer 2

好的，这是交易。我现在感觉很蠢。问题已经解决了。它不起作用的原因是在某些地方，我在MY OWN Date对象构造函数中颠倒了年份和日期。我把年，月，日直接放入查询（而不是问号）后发现了。无论如何，我希望这是一次很好的学习经历。

Android SQLiteDatabase无法插入或查询

2 个答案: