android - 如何从单选组中获取默认选择的单选按钮？

Question

我有一个由三个单选按钮组成的单选组 'yes','no','do not know'。我将 android:checkedButton="@id/r3" 设置为默认选择第三个单选按钮。我已经为单选组设置了 setOnCheckedChangeListener，它会在从 UI 中选择任何单选按钮时被调用。

我想在 onCreate 中为默认选中的单选按钮调用监听器，因为我正在对默认选中的代码执行一些值设置。

是否有可能在 onCreate 中获取单选组中默认选中的单选按钮并执行一些操作，稍后 setOnCheckedChangeListener 将处理来自 UI 的单选按钮

<RadioGroup
                    android:id="@+id/rg1"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:checkedButton="@id/r3"
                    android:orientation="horizontal"
                    android:weightSum="3">

                    <RadioButton
                        android:id="@+id/r1"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_weight="1"
                        android:text="Yes"
                        android:textColor="@color/fontBlackEnable" />

                    <RadioButton
                        android:id="@+id/r2"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_weight="1"
                        android:text="No"
                        android:textColor="@color/fontBlackEnable" />

                    <RadioButton
                        android:id="@+id/r3"
                        android:layout_width="wrap_content"
                        android:layout_height="wrap_content"
                        android:layout_weight="1"
                        android:checked="true"
                        android:text="@string/do_not_know" />

                </RadioGroup>

public class MyFragment extends Fragment {

    View rootView;
    Context context;
    RadioGroup mRadioAns3;



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        rootView = inflater.inflate(R.layout.my_fragment, container, false);
        context = container.getContext();
        mRadioAns3 = rootView.findViewById(R.id.rg1);

       //Todo: get default selected radiobutton and show toast on load of fragment


        mRadioAns3.setOnCheckedChangeListener(new RadioGroup.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(RadioGroup group, int checkedId) {
                Toast.makeText(context,((RadioButton) rootView.findViewById(checkedId)).getText() ,Toast.LENGTH_LONG ).show();
            }
        });

        return rootView;
    }


}

Answer 1

if(gender.getCheckedRadioButtonId()==-1)
{
    Toast.makeText(mContext, "Please select Gender", Toast.LENGTH_SHORT).show();
}
else
{
    // get selected radio button from radioGroup
    int selectedId = gender.getCheckedRadioButtonId();
    // find the radiobutton by returned id
    selectedRadioButton = (RadioButton)findViewById(selectedId);
    Toast.makeText(mContext, selectedRadioButton.getText().toString()+" is selected", Toast.LENGTH_SHORT).show();
}