如何从数据库中获取日期并检查它们是否重叠？

Question

我有一个存储所有事件的 sqlite 数据库。我以日期格式针对每个事件存储 StartTime 和 EndTime。

我有几天带有标签的片段和一个 activity 添加事件的片段。事件显示在另一个片段中。

现在我想检查事件是否相互重叠以及基于哪个应用程序应该显示消息。

如何在添加的事件中显示消息 activity 当用户保存事件时。

我该怎么做？

我已经尝试过这种方式，但仍然添加了具有相同开始时间和结束时间的事件：

ImageButton imageButton = (ImageButton)findViewById(R.id.imgbtn_fab);
imageButton.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        eventTitle = title.getText().toString();
        EventTableHelper db = new EventTableHelper(getApplication());
        List<EventData> events;
        events = db.getAllEvents();

        for (EventData eventData : events) {

            String datefrom = eventData.getFromDate();

            String[] times = datefrom.substring(11, 16).split(":");
            minutesFrom = Integer.parseInt(times[0]) * 60 + Integer.parseInt(times[1]);

            String dateTo = eventData.getToDate();

            //times = dateTo.substring(11,16).split(":");
            String[] times1 = dateTo.substring(11, 16).split(":");
            minutesTo = Integer.parseInt(times1[0]) * 60 + Integer.parseInt(times1[1]);
        }

        if (eventTitle.length() == 0) {
            Toast.makeText(getApplicationContext(), "Title can not be empty.", Toast.LENGTH_LONG).show();
        }
        else if(minutesFrom == minutesTo) {
            Toast.makeText(getApplicationContext(),"Event with same time exists.",Toast.LENGTH_LONG).show();
        }
        else
        {
            db.addEvent(new EventData(eventTitle, startTime, endTime, dayOfWeek, location));
            setResult(RESULT_OK, i);
            finish();
        }
    }
});

我得到这样的日期：

c = Calendar.getInstance();

year = c.get(Calendar.YEAR);
month = c.get(Calendar.MONTH);
day = c.get(Calendar.DAY_OF_MONTH);

hour = c.get(Calendar.HOUR_OF_DAY);
minute = c.get(Calendar.MINUTE);

df = new SimpleDateFormat("HH:mm a");
datefrom = c.getTime();
startTime = String.valueOf(datefrom);

aTime = df.format(datefrom.getTime());
showFromTime.setText(aTime);

c.add(Calendar.HOUR_OF_DAY, 1);
dateto = c.getTime();
endTime = String.valueOf(dateto);

bTime = df.format(dateto.getTime());
showToTime.setText(bTime);

我创建了一个 EventTableHelper:

public class EventTableHelper extends SQLiteOpenHelper {

    private static final String TABLE = "event";
    private static final String KEY_ID = "id";
    private static final String KEY_TITLE = "title";
    private static final String KEY_FROM_DATE = "datefrom";
    private static final String KEY_TO_DATE = "dateto";
    private static final String KEY_LOCATION = "location";
    private static final String KEY_DAY_OF_WEEK = "dayofweek";

    public EventTableHelper(Context context) {
        super(context, Constants.DATABASE_NAME, null, Constants.DATABASE_VERSION);

    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    }

    public void createTable(SQLiteDatabase db){
        String CREATE_EVENTS_TABLE = "CREATE TABLE " + TABLE+ "("
                + KEY_ID + " INTEGER PRIMARY KEY,"
                + KEY_TITLE + " TEXT,"
                + KEY_FROM_DATE + " DATE,"
                + KEY_TO_DATE + " DATE,"
                + KEY_DAY_OF_WEEK + " TEXT "
                + KEY_LOCATION + " TEXT" +  ")";
        db.execSQL(CREATE_EVENTS_TABLE);
    }
    // Upgrading database
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        db.execSQL("DROP TABLE IF EXISTS " + TABLE);

       // createTable(db);
       // onCreate(db);
    }

    public void addEvent(EventData event) {
        SQLiteDatabase db = this.getWritableDatabase();

        ContentValues values = new ContentValues();
        values.put(KEY_TITLE,event.getTitle());
        values.put(KEY_FROM_DATE, event.getFromDate());
        values.put(KEY_TO_DATE,event.getToDate());
        values.put(KEY_DAY_OF_WEEK,event.getDayOfWeek());
        values.put(KEY_LOCATION,event.getLocation());

        db.insert(TABLE, null, values);

        db.close();
    }

   EventData getEvent(int id) {

        SQLiteDatabase db = this.getReadableDatabase();
        EventData eventData = new EventData();
        Cursor cursor = db.query(TABLE, new String[]{KEY_ID,
                        KEY_TITLE, KEY_FROM_DATE, KEY_TO_DATE, KEY_LOCATION}, KEY_ID + "=?",
                new String[]{String.valueOf(id)}, null, null, null, null);

       if( cursor != null && cursor.moveToFirst() ) {
          eventData = new EventData(Integer.parseInt(cursor.getString(0)), cursor.getString(1), cursor.getString(2),
                   cursor.getString(3), cursor.getString(4));

       }
       return eventData;
    }

    public List<EventData> getAllEvents() {
        List<EventData> conList = new ArrayList<EventData>();

        String selectQuery = "SELECT  * FROM " + TABLE;

        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(selectQuery, null);

        if (cursor.moveToFirst()) {
            do {

                EventData event = new EventData();

                event.setId(Integer.parseInt(cursor.getString(0)));
                event.setTitle(cursor.getString(1));
                event.setFromDate(cursor.getString(2));
                event.setToDate(cursor.getString(3));
                event.setLocation(cursor.getString(4));

                conList.add(event);
            } while (cursor.moveToNext());
        }

        return conList;
    }
}

我尝试在 activity 中使用 getAll 事件函数来获取数据。

编辑：这是我当前的代码。

@Override
public void onClick(View v) {
    eventTitle = title.getText().toString();
    EventTableHelper db = new EventTableHelper(getApplication());
    List<EventData> events;
    // events = db.getOverlappingEvents(startTime,endTime);

    if (eventTitle.length() == 0) {
        Toast.makeText(getApplicationContext(), "Title can not be empty.", Toast.LENGTH_LONG).show();
    }
    else if(db.doesEventOverlap(startTime,endTime))
    {
        Toast.makeText(getApplicationContext(), "Event exists", Toast.LENGTH_LONG).show();
    }
    else
    {
        db.addEvent(new EventData(eventTitle, startTime, endTime, dayOfWeek, location));
        setResult(RESULT_OK, i);
        finish();
    }
}

Answer 1

minutesTo、minutesFrom 将只有数据库中最后一行的值。

我会尝试在 EventTableHelper 中做一个新功能：

List<EventData> getOverlappingEvents(Date startTime, Date endTime) {
    List<EventData> conList = new ArrayList<EventData>();

    String selectQuery = "SELECT  * FROM " + TABLE
      + " WHERE (" + KEY_FROM_DATE + " < '" + startTime
      + "' AND '" + startTime + "' < " + KEY_TO_DATE + ") OR "
      + " (" + KEY_FROM_DATE + " < '" + endTime
      + "' AND '" + endTime + "' < " + KEY_TO_DATE + ") OR "

      + " (" + KEY_FROM_DATE + " < '" + startTime
      + "' AND '" + endTime + "' < " + KEY_TO_DATE + ") OR "
      + " ('" + startTime + "' < " + KEY_FROM_DATE
      + " AND " + KEY_TO_DATE + " < '" + endTime + "')";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    if (cursor.moveToFirst()) {
        do {

            EventData event = new EventData();

            event.setId(Integer.parseInt(cursor.getString(0)));
            event.setTitle(cursor.getString(1));
            event.setFromDate(cursor.getString(2));
            event.setToDate(cursor.getString(3));
            event.setLocation(cursor.getString(4));

            conList.add(event);
        } while (cursor.moveToNext());
    }
    return conList;
}

并在 onClick 中：

events = db.getOverlappingEvents();
...

而不是：

else if(minutesFrom == minutesTo)

这个：

else if(events.size() > 0)

实际上它可以进一步优化，因为看起来您不需要重叠事件数据，如果至少有一个重叠事件则只需要一个布尔值：

boolean doesEventOverlap(Date startTime, Date endTime) {
    String selectQuery = "SELECT COUNT(*) FROM " + TABLE
      + " WHERE (" + KEY_FROM_DATE + " < '" + startTime
      + "' AND '" + startTime + "' < " + KEY_TO_DATE + ") OR "
      + " (" + KEY_FROM_DATE + " < '" + endTime
      + "' AND '" + endTime + "' < " + KEY_TO_DATE + ") OR "

      + " (" + KEY_FROM_DATE + " < '" + startTime
      + "' AND '" + endTime + "' < " + KEY_TO_DATE + ") OR "
      + " ('" + startTime + "' < " + KEY_FROM_DATE
      + " AND " + KEY_TO_DATE + " < '" + endTime + "')";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    if (cursor.moveToFirst()) {
        do {
            EventData event = new EventData();
            return cursor.getInt(0) > 0;
        } while (cursor.moveToNext());
    }
    return false;
}

并在 onClick 中代替：

else if(minutesFrom == minutesTo)

这个：

else if(db.doesEventOverlap())

如何从数据库中获取日期并检查它们是否重叠？

How to get dates from database and check if they overlaps?

java

android

sqlite

date

overlap