public void calculate(View view){
    startActivity(new Intent(MainActivity.this, DrinksActivity.class));
}

<Button
    android:id="@+id/genderbutton"
    android:layout_width="100dp"
    android:layout_height="50dp"
    android:layout_below="@+id/radioGroup1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="77dp"
    android:onClick="calculate"
    android:text="@string/next2"
    android:textColor="#FFFFFF" />

<activity
    android:name="com.example.bac.DrinksActivity"
    android:label="@string/title_activity_drinks" >
</activity>