Question

我正在尝试插入SQLite数据库。但我得到一个例外，说数据库没有打开。

这是MainActivity.java

的部分

     // testing event table.
     int id = 1;
     int fid = 1;
     String name = "intro";
     String manager = "Sandeep";
     String time = "june 23 6 PM" ;
     String venue = "vmcc";

     Event e  = new Event();
     e.setEventId(id);
     e.setFestId(fid);
     e.setManager(manager);
     e.setName(name);
     e.setTime(time);
     e.setVenue(venue);

     EventDatabaseManager edb = new EventDatabaseManager(this);
     edb.addEvent(e);

这是EventDatabaseManager.java类的一部分。我从插入行说java.illegalstateexception得到例外。数据库未打开。

public class EventDatabaseManager extends SQLiteOpenHelper
{
  private static final String DATABASE_NAME = "events.db";
  private static  int DATABASE_VERSION = 1;

  // table name.
  private static final String TABLE_EVENTS = "events";
  // column names.
  private static final String KEY_ID = "id";
  private static final String KEY_FESTID = "festid";
  private static final String KEY_NAME = "title";
  private static final String KEY_MANAGER = "manager";
  private static final String KEY_TIME = "time";
  private static final String KEY_VENUE = "venue";

  private static final int FESTID_INDEX = 1;
  private static final int NAME_INDEX = 2;
  private static final int MANAGER_INDEX = 3;
  private static final int TIME_INDEX = 4;
  private static final int VENUE_INDEX = 5;

public EventDatabaseManager(Context context)
{
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}


@Override
public void onCreate(SQLiteDatabase database) 
{
    database.execSQL("DROP TABLE IF EXISTS " + TABLE_EVENTS);
    Log.d("database","creating db");
    String CREATE_EVENTS_TABLE = "CREATE TABLE " + TABLE_EVENTS
            + "( " + KEY_ID + " INTEGER PRIMARY KEY, " + KEY_FESTID + " INTEGER , "+
              KEY_NAME + " TEXT , " + KEY_MANAGER + " TEXT , "+
            KEY_TIME + " TEXT , " + KEY_VENUE + " TEXT )";

        Log.d("create fn",CREATE_EVENTS_TABLE);

     database.execSQL(CREATE_EVENTS_TABLE);


}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub
    // Drop older books table if existed
    db.execSQL("DROP TABLE IF EXISTS "+ TABLE_EVENTS);

    // create fresh books table

    this.onCreate(db);  
}

/**
 * Adding a new event.
 */
public void addEvent(Event e) 
{
    try{
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();


        /**
         * checking to see if the event is already added or not.
         */
        ArrayList<Event> list = getAllEvents();
        Event testEvent = new Event();
        Iterator<Event> in = list.iterator();
        while(in.hasNext())
        {
            testEvent = in.next();
            if(testEvent.getEventId() == e.getEventId() && testEvent.getFestId() == e.getFestId())
                {
                // TODO : showing error.
                return; 
                }
        }


        values.put(KEY_FESTID, e.getFestId());
        values.put(KEY_NAME, e.getName());
        values.put(KEY_MANAGER, e.getManager());
        values.put(KEY_TIME, e.getTime());
        values.put(KEY_VENUE, e.getVenue());
        Log.d("adding event" , "values row created.");
        // Inserting Row

        db.insert(TABLE_EVENTS, null, values);
        Log.d("adding event" , "event row added.");
        //db.close(); // Closing database connection
        }catch(Exception ex)
        {
            Log.d("adding event" , "exception caught" +ex);
        }
}

Answer 1

您必须创建数据库管理器对象，然后必须在其上调用getWriteableDatabase()方法。调用此方法时，Android系统将打开您的数据库，如果尚未创建，则会调用onCreate，或者如果版本已过时，则会调用onUpdate。

插入sqlite数据库时数据库未打开异常

1 个答案: