android - 完成尚未停用或关闭的 Cursor

Question

好的，我是 android 开发的新手，或者任何开发并遇到此错误的新手。我想做的是每次用户选择一个微调项然后程序创建一个列表。我有一个用于获取列表结果的 DatabaseHelper 类。但问题是它永远不会创建列表，并且会出现此错误。

Activity 使用的 DatabaseHelper 方法；

 public int[] searchbyLetter(String letter) {
    // TODO Auto-generated method stub
    int[] results = new int[100];
    int count = 0;

    String[] columns = new String[] { KEY_MINERALID };
    Cursor c = minerals.query(DATABASE_TABLE, columns, KEY_LETTER + "= '"
            + letter + "'", null, null, null, null);
    if (c.moveToFirst()) {
        results[count] = c.getInt(c.getColumnIndex(KEY_MINERALID));
    }

    while (c.moveToNext()) {
        count++;
        results[count] = c.getInt(c.getColumnIndex(KEY_MINERALID));
    }
    c.close();
    return results;
}

 public String getName(int _id) {
    // TODO Auto-generated method stub
    String[] columns = new String[] { KEY_NAME };
    Cursor c = minerals.query(DATABASE_TABLE, columns, KEY_MINERALID + "="
            + _id, null, null, null, null);
    c.moveToFirst();
    int iName = c.getColumnIndex(KEY_NAME);
    String result = c.getString(iName);
    c.close();
    return result;
}

这是我的 ListActivity 类；

public class Az extends ListActivity {

String[] spAzPaht = { "A", "B", "C", "D", "E", "F", "G", "H", "I", "J",
        "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W",
        "Y", "Z" };
ArrayList<AzOrder> azOrder;
AzOrderAdapter azOrderAdapter;
Spinner spAZ;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
            WindowManager.LayoutParams.FLAG_FULLSCREEN);
    setContentView(R.layout.az);
    ArrayAdapter<String> spAzAdpt = new ArrayAdapter<String>(Az.this,
            android.R.layout.simple_spinner_item, spAzPaht);

    spAZ = (Spinner) findViewById(R.id.spAZ);
    spAZ.setAdapter(spAzAdpt);
    azOrder = new ArrayList<AzOrder>();
    this.azOrderAdapter = new AzOrderAdapter(Az.this, R.layout.az, azOrder);
    setListAdapter(azOrderAdapter);

    spAZ.setOnItemSelectedListener(new OnItemSelectedListener() {

        public void onItemSelected(AdapterView<?> arg0, View arg1,
                int arg2, long arg3) {

            getSearches();

        }

        public void onNothingSelected(AdapterView<?> arg0) {
            // TODO Auto-generated method stub

            getSearches();

        }
    });

}


private void getSearches() {
    DatabaseHelper myDBHelper = new DatabaseHelper(Az.this);

    try {
        myDBHelper.createDataBase();
    } catch (IOException e) {
        // TODO: handle exception
        e.printStackTrace();
    }
    try {
        myDBHelper.openDataBase();
    } catch (SQLException sqle) {
        throw sqle;
        // TODO: handle exception
    }
    int position = spAZ.getSelectedItemPosition();
    String letter = spAzPaht[position];
    int[] results = myDBHelper.searchbyLetter(letter);

    try {

        azOrder = new ArrayList<AzOrder>();
        AzOrder AZO = new AzOrder();
        for (int i = 0; i < results.length; i++) {
            AZO.setName(myDBHelper.getName(results[i]));
            AZO.setMineral_ID(results[i]);
            azOrder.add(AZO);
        }
        Thread.sleep(5000);
        Log.i("Array", "" + azOrder.size());
    } catch (Exception e) {
        // TODO: handle exception
        Log.e("BACKGROUND_PROC", e.getMessage());
    }
    myDBHelper.close();


}

这是我得到的错误

    E/Cursor(295): Finalizing a Cursor that has not been deactivated or 
    closed. database = /data/data/com.mineralidentifier.degosa.test1/databases/
    minerals, table = minerals, query = SELECT minerals_name FROM minerals 
    WHERE _id=0

    E/Cursor(295): android.database.sqlite.DatabaseObjectNotClosedException: 
    Application did not close the cursor or database object that was opened 
    here

    E/Cursor(295):  at android.database.sqlite.SQLiteCursor.<init>
    (SQLiteCursor.java:210)

    E/Cursor(295):  at android.database.sqlite.SQLiteDirectCursorDriver.query
    (SQLiteDirectCursorDriver.java:53)

Answer 1

看起来 Cursor 没有被关闭。我看到你有 c.close()，但可能无法访问它，因为在它之前抛出了另一个异常。而且，该异常被 DatabaseObjectNotClosedException 屏蔽，最终被抛出以屏蔽原始异常。最好将其包装在 finally 子句中，以确保无论是否抛出异常，它始终关闭。

Cursor c = ...
try {
   ...
} finally {
   c.close();
}

如果您这样做，那么它可能会告诉您真正的问题是什么。不幸的是，由于我们没有看到完整的异常堆栈跟踪，因此我们无法看到在您的代码中究竟从何处抛出 DatabaseObjectNotClosedException。我们只能看到它从 android 代码中的什么地方抛出，但我们看不到过去的 SQLiteDirectCursorDriver.query。