android - 我有一个警告对话框并使用 setSingleChoiceItems 设置所选项目，但想从顶部显示列表

Question

我有一个警告对话框窗口，并使用下面的代码将列表中的选项设置为默认值。我在 Stackoverflow 中找不到任何合适的解决方案，所以添加了问题

CustomDialog 类将 Dialog 返回到我的 Activity

public class CustomDialog extends DialogFragment {

  @Override
  public Dialog onCreateDialog(Bundle savedInstanceState) {
         ...
    AlertDialog.Builder b = new AlertDialog.Builder();
    b.setSingleChoiceItems(Language.names, 5, new OnClickListener() {
       ....
    }

    AlertDialog dialog = b.create();

    return dialog;
 }

Activity 中:

    FragmentManager manager = getFragmentManager();
    CustomDialog alert = new CustomDialog();

    // Creating a bundle object to store the selected item's index
    Bundle b = new Bundle();

    // Storing the selected item's index in the bundle object : Get current language
    // code and set the position
    b.putInt("position", 5); // sending the 5

    // Setting the bundle object to the dialog fragment object
    alert.setArguments(b);

    // Creating the dialog fragment object, which will in turn open the alert dialog window
    alert.show(manager, "alert_dialog_radio");

现在它显示正确的特定位置，但我遇到的问题是它滚动位置并将该位置保持在顶部。

有没有一种方法可以将列表设置为从位置 0 开始显示，但所选项目是 5。所以想法是传递 5 并显示 5 已选中，但它应该从 0 开始显示。

Answer 1

不是在 setSingleChoiceItems() 调用中传递所选项目的索引，而是传递 -1 以指示未选中任何项目，然后手动选择项目您想要在 AlertDialog 显示之后。

public class CustomDialog extends DialogFragment {

    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        AlertDialog.Builder b = new AlertDialog.Builder(...);
        ...

        // We can just pass -1 here, since we'll be
        // setting the selected item later anyway

        b.setSingleChoiceItems(Language.names, -1, new OnClickListener() {
                ....
            }
        );

        AlertDialog dialog = b.create();
        return dialog;
    }

    @Override
    public void onStart() {
        super.onStart();

        // Grab the position from the arguments,
        // and set that item as checked

        final int position = getArguments().getInt("position");
        final AlertDialog dialog = (AlertDialog) getDialog();
        dialog.getListView().setItemChecked(position, true);
    }
}