Record in the database

Question

Trying out site parse.com load data into the database

@Override
  public void onClick(View v) {


    cv = new ContentValues();


    db = dbHelper.getWritableDatabase();        

    switch (v.getId()) {

    case R.id.btnAdd:

            query = new ParseQuery("mens");
               query.setLimit(50);             
                query.findInBackground(new FindCallback() {
                public void done(List<ParseObject> mens, ParseException e) {
                  if (e == null) {
                        for ( int i = 0; i < 50; i++) {    

                             stGet = mens.get(i).getString("Str");                                 
                             cv.put("email", stGet);

                             long rowID = db.insert("mytable", null, cv);

                            }                
                     } 
                  }
                 });             

      break;

    dbHelper.close();
}

class DBHelper extends SQLiteOpenHelper {

    public DBHelper(Context context) {
          super(context, "myDB", null, 1);

    }

    @Override
    public void onCreate(SQLiteDatabase db) {

      db.execSQL("create table mytable ("
          + "id integer primary key autoincrement,"
          + "email text" + ");");
    }

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

    }
  }

On the emulator get

java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /data/data/com.project.test/databases/myDB at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:55) at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java: 1437) at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1339) at com.project.test.MainActivity$1.done(MainActivity.java:347) at com.parse.FindCallback.internalDone(FindCallback.java:48) at com.parse.FindCallback.internalDone(FindCallback.java:33) at com.parse.BackgroundTask.onPostExecute(BackgroundTask.java:50) at com.parse.BackgroundTask.onPostExecute(BackgroundTask.java:16) at android.os.AsyncTask.finish(AsyncTask.java:631) at android.os.AsyncTask.access$600(AsyncTask.java:177) at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:137) at android.app.Activ ityThread.main(ActivityThread.java:5103) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:525) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) at dalvik.system.NativeStart.main(Native Method)

On a real device

FATAL EXCEPTION: main java.lang.IllegalStateException: database not open at android.database.sqlite.SQLiteDatabase.insertWithOnConflict(SQLiteDatabase.java: 1671) at android.database.sqlite.SQLiteDatabase.insert(SQLiteDatabase.java:1571) at com.project.test.MainActivity$1.done(MainActivity.java:347) at com.parse.FindCallback.internalDone(FindCallback.java:48) at com.parse.FindCallback.internalDone(FindCallback.java:33) at com.parse.BackgroundTask.onPostExecute(BackgroundTask.java:50) at com.parse.BackgroundTask.onPostExecute(BackgroundTask.java:16) at android.os.AsyncTask.finish(AsyncTask.java:417) at android.os.AsyncTask.access$300(AsyncTask.java:127) at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:429) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:130) at android.app.ActivityThread.main(ActivityThread.java:3687) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:507 ) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625) at dalvik.system.NativeStart.main(Native Method)

long rowID = db.insert("mytable", null, cv); // MainActivity.java:347

What's the problem?

Answer 1

我认为您在使用DataBase之前错过了打开DataBase ，或者您试图在不再次打开的情况下open已关闭的DataBase

Answer 2

Try not closing the database by removing this line:

dbHelper.close();

As said in this post , you don't have to close the database in SQLite. Actually, I think you should not close.

In my case, I just use one single instance for DatabaseHelper and it works fine, even with multiple threads acessing the database. When the app exits, the database connection is closed by the OS.

Just remind to close the cursors, instead.

Here is another reference that may help: What are the best practices for SQLite on Android?