Differentiate between two radio groups in same XML layout

I am having two radio group inside same xml layout. I am using oncheckedChanged listener in my MainActivity.java file. I want to differentiate between the two Radio groups using its listener. How to make use of parameter of RadioGroup Inside the Listener.

@Override
public void onCheckedChanged(RadioGroup group, int checkedId) {

    switch (checkedId) {

    case R.id.rexcellent:

        Toast.makeText(getApplicationContext(), "execellnt",
                Toast.LENGTH_SHORT).show();

        break;
    case R.id.rverygood:
        Toast.makeText(getApplicationContext(), "very good",
                Toast.LENGTH_SHORT).show();

        break;
    case R.id.rgood:
        Toast.makeText(getApplicationContext(), "good", Toast.LENGTH_SHORT)
                .show();

        break;
    case R.id.raverage:
        Toast.makeText(getApplicationContext(), "average",
                Toast.LENGTH_SHORT).show();

        break;
    case R.id.rmale:
        Toast.makeText(getApplicationContext(), "Male",
                Toast.LENGTH_SHORT).show();

        break;
    case R.id.rfemale:
        Toast.makeText(getApplicationContext(), "female",
                Toast.LENGTH_SHORT).show();

        break;

    }

} 

here is my Xml code :

    <TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Rate Smartherd Tutorials ?"
    android:textAppearance="?android:attr/textAppearanceLarge" />

    <RadioGroup
    android:id="@+id/rgroup"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" >

    <RadioButton
        android:id="@+id/rexcellent"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:checked="true"
        android:text="Excellent" />

    <RadioButton
        android:id="@+id/rverygood"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Very Good" />

    <RadioButton
        android:id="@+id/rgood"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Good" />

    <RadioButton
        android:id="@+id/raverage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Average" />
</RadioGroup>

<TextView
    android1:id="@+id/textView2"
    android1:layout_width="wrap_content"
    android1:layout_height="wrap_content"
    android1:text="How is shreks ?" />

<RadioGroup
    android1:id="@+id/rg2"
    android1:layout_width="wrap_content"
    android1:layout_height="wrap_content" >

    <RadioButton
        android1:id="@+id/rmale"
        android1:layout_width="wrap_content"
        android1:layout_height="wrap_content"
        android1:checked="true"
        android1:text="MALE" />

    <RadioButton
        android1:id="@+id/rfemale"
        android1:layout_width="wrap_content"
        android1:layout_height="wrap_content"
        android1:text="Female" />

    </RadioGroup>

</LinearLayout>

I want to use switch case statement only. And want to know the use of having "RadioGroup group " inside the listener. What is the role of that?