Can't get CheckedRadioButtonId from within a dialog

Question

This is my first post on Stackoverflow and so far it's been great finding a lot of information here, thank you for that!

I'm trying to have a list with selectable items. when you press the item it may prompt a dialog with 3 radiobuttons. I want to get the ID from the selected radiobutton but for now it always returns the same value. Since i made option 1(Klein) default. pressing a different button and getting that value won't help.

I'm looking forward to tips/tricks/help that you can provide me with(I recently started on android programming, so correct me where I'm wrong!)

// Listview on child click listener
    expListView.setOnChildClickListener(new OnChildClickListener() {

        @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
        @Override
        public boolean onChildClick(ExpandableListView parent, View v,
                                    int groupPosition, int childPosition, long id) {
            // TODO Auto-generated method stub
            Toast.makeText(
                    getApplicationContext(),
                    listDataHeader.get(groupPosition)
                            + " : "
                            + listDataChild.get(
                            listDataHeader.get(groupPosition)).get(
                            childPosition), Toast.LENGTH_SHORT)
                    .show();

                if (groupPosition == 4) {

                    LayoutInflater li = LayoutInflater.from(context);
                    final View myView = li.inflate(R.layout.dialog, null);

                    final AlertDialog.Builder Builder = new AlertDialog.Builder(context);


                    // set layout
                    Builder.setView(dialog);


                    // set title
                    Builder.setTitle("Maak uw keuze");

                    // set dialog message
                    Builder
                            .setCancelable(true)
                            .setPositiveButton("Bestellen", new DialogInterface.OnClickListener() {

                                public void onClick(DialogInterface dialog, int id) {



                                    RadioGroup radioGroup1 = (RadioGroup)myView.findViewById(R.id.RadioGroup);
                                    String radiovalue = ((RadioButton)myView.findViewById(radioGroup1.getCheckedRadioButtonId())).getText().toString();

                                   // int selectId =radioGroup1.getCheckedRadioButtonId();

                                    dialog.cancel();

                                    Toast.makeText(MainActivity.this, radiovalue,
                                            Toast.LENGTH_SHORT).show();
                                }
                            });


                    // create alert dialog
                    AlertDialog alertDialog = Builder.create();

                    // show it
                    alertDialog.show();
                }

my xml(dialog.xml):

 <RadioGroup
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/RadioGroup"
    android:orientation="horizontal"
    android:layout_below="@+id/textView"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:checkedButton="@+id/radioButton1"
    >


<RadioButton
    android:text="Klein"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/radioButton1"
    android:layout_alignBaseline="@+id/radioButton"
    android:layout_alignBottom="@+id/radioButton"
    android:layout_toRightOf="@+id/radioButton"
    android:layout_toEndOf="@+id/radioButton"
    />

<RadioButton
    android:text="Middel"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/radioButton2"
    android:layout_below="@+id/textView"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<RadioButton
    android:text="Groot"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/radioButton3"
    android:layout_alignBaseline="@+id/radioButton2"
    android:layout_alignBottom="@+id/radioButton2"
    android:layout_toRightOf="@+id/radioButton2"
    android:layout_toEndOf="@+id/radioButton2"
    android:layout_marginLeft="17dp"
    android:layout_marginStart="17dp" />

</RadioGroup>

Answer 1

I figured it out!

I had:

LayoutInflater li = LayoutInflater.from(context); final View myView = li.inflate(R.layout.dialog, null);

                final AlertDialog.Builder Builder = new AlertDialog.Builder(context);


                // set layout
                Builder.setView(dialog);

This Build.setView should refer to my inflater... not the XML itself....

So Builder.setView(myView); Solved the issue!

Answer 2

UPDATED CODE:

.setPositiveButton("Bestellen", new DialogInterface.OnClickListener() {

    public void onClick(DialogInterface dialog, int id) {

        //keep this variables global outside onCreate just like ExpandableListView expListView;
        RadioGroup radioGroup1; //this
        RadioButton radioButton; // and this too keep global

        radioGroup1 = (RadioGroup)myView.findViewById(R.id.RadioGroup);
        int something = radioGroup1.getCheckedRadioButtonId();
        radioButton = (RadioButton)myView.findViewById(something);
        String radioValue = radioButton.getText().toString();

        dialog.cancel();

        Toast.makeText(MainActivity.this, radioValue,
                Toast.LENGTH_SHORT).show();
    }
});

Remove the attribute from XML:

<RadioGroup
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/RadioGroup"
android:orientation="horizontal"
android:layout_below="@+id/textView"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:checkedButton="@+id/radioButton1" //removing this helped me so try to remove and apply the java code. 
>