ActivityGroup: Jumping inside and outside of Activity

Source code introduction

A source code I saw on the Internet is about jumping inside and outside the Activity in ActivityGroup. Friends who are interested can study it!
Source code screenshot

Source code snippet

 public   class MainActivityGroup extends AbsActivityGroup{ 
  
 // The first method that needs to be implemented, directly return the layout of the ActivityGroup implementation class  
 // Note that this layout must have a layout with the id activity_group_container to hold the sub-Activity layout  
 @Override  
 protected   int getLayoutResourceId() {
 // Arrange tabs horizontally  
 return R.layout.activity_group_bottom5_layout;
 // If the tabs are arranged vertically, you can return to the following layout  
 //return R.layout.activity_group_left5_layout;  
 } 
  
 // The second method to be implemented returns the id of the radioButton corresponding to the tab in the layout  
 @Override  
 protected   int [] getRadioButtonIds() {
 return   new   int [] { R.id.activity_group_radioButton0,
                R.id.activity_group_radioButton1,
                R.id.activity_group_radioButton2,
                R.id.activity_group_radioButton3,
                R.id.activity_group_radioButton4 };
 } 
  
 // The third method to be implemented is the icon corresponding to the radioButton in the above method. Note that the icon size should be adjusted to the appropriate size  
 @Override  
 protected   int [] getRadioButtonImageIds() {
 return   new   int [] { R.drawable.icon2, R.drawable.icon2, R.drawable.icon2,
                R.drawable.icon2, R.drawable.icon2, };
 } 
  
 // The fourth method that needs to be implemented is the text corresponding to the radioButton, which is the text of the tab label.  
 // ***Don't make it too long, otherwise you need to adjust the text size in the layout file to fit the interface  
 @Override  
 protected String[] getRadioButtonTexts() {
 return   new String[]{ "A" , "B" , "C" , "D" , "E" };
 } 
  
 // The fifth method to be implemented returns the first sub-Activity corresponding to each tab (note that it must be inherited from AbsSubActivity)  
 @SuppressWarnings ( "unchecked" )
 @Override  
 public Class<!--? extends Activity-->[] getClasses() {
        Class<!--? extends Activity-->[] classes = new Class[] { A1Activity. class ,
                B1Activity. class , C1Activity. class , D1Activity. class ,
                E1Activity.class };
 return classes;
 } 
  
 }