CursorIndexOutOfBoundsException 问题：请求索引 4，大小为 4

Question

我想为每个制造商显示一​​个带有一些描述的 AlertDialog，为此，我正在使用此代码：

protected boolean onTap(int index) {
            db = openHelper.getWritableDatabase();

            String[] result_columns = new String[] {COL_DESCRI};

            Cursor cur = db.query(true, TABLE_COORD, result_columns,
             null, null, null, null, null, null);

                 cur.moveToPosition(index);
                String description = cur.getString(cur.getColumnIndexOrThrow("description"));

                AlertDialog.Builder dialog = new AlertDialog.Builder(Geo.this);
                dialog.setTitle("Infos.");
                dialog.setMessage(description);
                dialog.setPositiveButton("OK", new OnClickListener() {    
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
                dialog.show();

                //cur.moveToNext();

             cur.close();
             db.close();

            return true;
        }

问题是有一些标记表明 alertdialog 结果是正确的，还有一些标记表明当我点击它时我有一个 FC。 日志猫：

08-23 17:41:37.531: ERROR/AndroidRuntime(10004): Uncaught handler: thread main exiting due to uncaught exception
08-23 17:41:37.550: ERROR/AndroidRuntime(10004): android.database.CursorIndexOutOfBoundsException: Index 4 requested, with a size of 4
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.database.AbstractCursor.checkPosition(AbstractCursor.java:580)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.database.AbstractWindowedCursor.checkPosition(AbstractWindowedCursor.java:214)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.database.AbstractWindowedCursor.getString(AbstractWindowedCursor.java:41)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at carburant.android.com.Geo$ItemizedOverlayPerso.onTap(Geo.java:244)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.google.android.maps.ItemizedOverlay.onTap(ItemizedOverlay.java:453)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.google.android.maps.OverlayBundle.onTap(OverlayBundle.java:83)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.google.android.maps.MapView$1.onSingleTapUp(MapView.java:346)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.GestureDetector.onTouchEvent(GestureDetector.java:506)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.google.android.maps.MapView.onTouchEvent(MapView.java:628)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.View.dispatchTouchEvent(View.java:3709)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:852)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:884)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1659)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1107)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.app.Activity.dispatchTouchEvent(Activity.java:2061)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1643)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1691)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.os.Handler.dispatchMessage(Handler.java:99)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.os.Looper.loop(Looper.java:123)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at android.app.ActivityThread.main(ActivityThread.java:4363)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at java.lang.reflect.Method.invokeNative(Native Method)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at java.lang.reflect.Method.invoke(Method.java:521)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
08-23 17:41:37.550: ERROR/AndroidRuntime(10004):     at dalvik.system.NativeStart.main(Native Method)

当我将cur.moveToPosition(index); 放在String description = cur.getString(cur.getColumnIndexOrThrow("description")); 下时，我有Index -1 requested, with a size of 4 否则，就像上面的代码Index 4 requested, with a size of 4

Answer 1

数组索引以0 开头，而不是1。您的第四个元素存储在索引3。

当我把 cur.moveToPosition(index);在 String description = cur.getString(cur.getColumnIndexOrThrow("description"));我请求了索引 -1，否则大小为 4，如上面的代码请求索引 4，大小为 4

当第一次返回行集时，光标将位于位置-1，即第一行之前。

Answer 2

刚打电话
Cursor cur = db.query(true, TABLE_COORD, result_columns, null, null, null, null, null, null);

您的光标将位于 -1 位置，如果您在光标位于 -1 索引时获取数据，则会出现此异常。
当您第一次调用 cur.moveToPosition(index-1); 时，您的索引值可能为 0，即问题。

Answer 3

错误肯定在代码String description = cur.getString(cur.getColumnIndexOrThrow("description")); 中，因为您没有这样的列。您只有 COL_DESCRI 列，可能与“描述”不匹配