尝试重新打开一个已经关闭的对象错误 Android SQLite

Question

我正在尝试构建一个简单的待办事项列表应用程序，将用户输入添加到列表视图，但不断收到此错误

public List<Task> getAllTasks() {
    List<Task> taskList = new ArrayList<Task>();

    String selectQuery = "SELECT  * FROM " + TABLE_TASKS;

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


    if (cursor.moveToFirst()) {
        do {
            Task task = new Task();
            task.setId(cursor.getInt(0));
            task.setTaskName(cursor.getString(1));
            task.setStatus(cursor.getInt(2));
            // Adding contact to list
            taskList.add(task);
        } while (cursor.moveToNext());
    }

    // return task list
    return taskList;
}

在这一行出现错误 SQLiteDatabase db = this.getWritableDatabase();

  @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_task);
    db = new TaskerDbHelper(this);
    list = db.getAllTasks();
    adapt = new MyAdapter(this, R.layout.list_inner_view, list);
    ListView listTask = (ListView) findViewById(R.id.listView1);
    listTask.setAdapter(adapt);
}

这里：list = db.getAllTasks();

Caused by: java.lang.IllegalStateException: attempt to re-open an already-closed object: SQLiteDatabase: /data/data/activfy.activfy/databases/taskerManager
                                                                 at android.database.sqlite.SQLiteClosable.acquireReference(SQLiteClosable.java:55)
                                                                 at android.database.sqlite.SQLiteDatabase.endTransaction(SQLiteDatabase.java:520)
                                                                 at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:263)
                                                                 at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:164)
                                                                 at activfy.activfy.TaskerDbHelper.getAllTasks(TaskerDbHelper.java:73)
                                                                 at activfy.activfy.GoalActivity.onCreate(GoalActivity.java:32)

编辑：

@Override
public void onCreate(SQLiteDatabase db) {

    String sql = "CREATE TABLE IF NOT EXISTS " + TABLE_TASKS + " ( "
            + KEY_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + KEY_TASKNAME
            + " TEXT, " + KEY_STATUS + " INTEGER)";
    db.execSQL(sql);

    db.close();
}




 @Override
public void onUpgrade(SQLiteDatabase db, int oldV, int newV) {
    // Drop older table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_TASKS);
    // Create tables again
    onCreate(db);
}

Answer 1

您不应该在 onCreate() 中传递给您的 SQLiteDatabase 上调用 close()，因为您不拥有它。

Answer 2

试试这个：

public List<Task> getAllTasks() {
List<Task> taskList = new ArrayList<Task>();

String selectQuery = "SELECT  * FROM " + TABLE_TASKS;

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

if (cursor.moveToFirst()) {
    do {
        Task task = new Task();
        task.setId(cursor.getInt(0));
        task.setTaskName(cursor.getString(1));
        task.setStatus(cursor.getInt(2));
        // Adding contact to list
        taskList.add(task);
    } while (cursor.moveToNext());
}
 finally
    {
        if (cursor != null)
        {
            cursor.close();
            db.close();
        }

// return task list
return taskList;
 }

并且在您的 OnCreat() 中，您不应该关闭您的数据库。

尝试重新打开一个已经关闭的对象错误 Android SQLite

Attempt to re-open an already closed object error Android SQLite

sqlite

android

android-sqlite