Android：如何从Sqlite检索微调器中的特定列

Question

我在Android应用程序中使用SQLite数据库。我只希望在微调器中检索到一列。 当我运行该应用程序时，该应用程序崩溃了。 我的日志猫显示：

对字段插槽0,1的错误请求。 numRows = 1，numColumns = 1

以下是用于从数据库检索数据并将其放入微调器（NewleadActivity.class）的代码。

这是我的适配器类

public class DbHelper extends SQLiteOpenHelper
{
     // Database Version
    @SuppressWarnings("unused")
    private static final int DATABASE_VERSION = 1;

   // Database Name
    static String DATABASE_NAME="define_products_database";

    // Labels table name
    public static final String TABLE_DEFINE_PRODUCT_NAME="define_products";

     // Labels Table Columns names
    public static final String KEY_PRODUCTS_NAME="product_name";
    public static final String KEY_PRODUCTS_DETAILS="products_details";
    public static final String KEY_ID="id";

    public DbHelper(Context context) {
        super(context, DATABASE_NAME, null, 1);

    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        String CREATE_TABLE="CREATE TABLE "+TABLE_DEFINE_PRODUCT_NAME+" ("+KEY_ID+" INTEGER PRIMARY KEY, "+KEY_PRODUCTS_NAME+" TEXT, "+KEY_PRODUCTS_DETAILS+" TEXT)";
        db.execSQL(CREATE_TABLE);

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS "+TABLE_DEFINE_PRODUCT_NAME);
        onCreate(db);

    }


     /**
     * Getting all labels
     * returns list of labels
     * */

    public List<String> getAllLabels(){
        List<String> labels = new ArrayList<String>();

        // Select All Query
        String selectQuery = " SELECT " + KEY_PRODUCTS_NAME + " FROM "+ TABLE_DEFINE_PRODUCT_NAME;

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

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                labels.add(cursor.getString(1));
            } while (cursor.moveToNext());
        }

        // closing connection
        cursor.close();
        db.close();

        // returning lables
        return labels;
    }

}

这是微调器随附的活动代码

public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.new_lead_activity5);
spinner_Products=(Spinner)findViewById(R.id.products_Spinner);

loadSpinnerData();

}



private void loadSpinnerData() {
        // database handler
        DbHelper db = new DbHelper(getApplicationContext());

        // Spinner Drop down elements
        List<String> lables = db.getAllLabels();

        // Creating adapter for spinner
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this,
                android.R.layout.simple_spinner_item, lables);

        // Drop down layout style - list view with radio button
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        // attaching data adapter to spinner
        spinner_Products.setAdapter(dataAdapter);
    }

}

这是我的原木猫。

11-27 11:28:28.548: E/AndroidRuntime(2150): FATAL EXCEPTION: main
11-27 11:28:28.548: E/AndroidRuntime(2150): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.lead_management_project/com.lead_management_project.New_Lead_Activity5}: java.lang.IllegalStateException: get field slot from row 0 col 1 failed
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.os.Looper.loop(Looper.java:123)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.app.ActivityThread.main(ActivityThread.java:3683)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at java.lang.reflect.Method.invokeNative(Native Method)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at java.lang.reflect.Method.invoke(Method.java:507)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at dalvik.system.NativeStart.main(Native Method)
11-27 11:28:28.548: E/AndroidRuntime(2150): Caused by: java.lang.IllegalStateException: get field slot from row 0 col 1 failed
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.database.CursorWindow.getString_native(Native Method)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.database.CursorWindow.getString(CursorWindow.java:329)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:49)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at com.db_mgmt.DbHelper.getAllLabels(DbHelper.java:65)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at com.lead_management_project.New_Lead_Activity5.loadSpinnerData(New_Lead_Activity5.java:123)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at com.lead_management_project.New_Lead_Activity5.onCreate(New_Lead_Activity5.java:80)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-27 11:28:28.548: E/AndroidRuntime(2150):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
11-27 11:28:28.548: E/AndroidRuntime(2150):     ... 11 more

Answer 1

伙计，您只在语句中查询单个列并要求第二个，只使用下面的方法，我只将Index从1更改为0。

   public List<String> getAllLabels(){
        List<String> labels = new ArrayList<String>();

        // Select All Query
        String selectQuery = " SELECT " + KEY_PRODUCTS_NAME + " FROM "+ TABLE_DEFINE_PRODUCT_NAME;

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

        // looping through all rows and adding to list
        if (cursor.moveToFirst()) {
            do {
                labels.add(cursor.getString(0));
            } while (cursor.moveToNext());
        }

        // closing connection
        cursor.close();
        db.close();

        // returning lables
        return labels;
    }