In-depth analysis of Android dynamic management fragment: "Do you know these components?"

1. The relationship between Fragment and Activity

To understand dynamic management of Fragment, you must first understand the relationship between Fragment and Activity

Fragment can be understood as dividing Activity into several fragments. Fragment is part of Activity, and its life cycle depends on Activity. It cannot exist independently. It is not difficult to understand that all Fragment management (finding, adding, deleting, replacing) should be done in the Activity that Fragment depends on, that is, Activity is the place for Fragment interaction. Don't try to manage another Fragment in a Fragment. Although it can achieve the required functions, it does not meet the specifications. To complete specific operations on Fragment, you need to use FragmentManager component.

2. Use FragmentManager component

The key code for using the FragmentManager component is as follows:

 //1. Create a FragmentManager component  
 FragmentManager fm= super .getSupportFragmentManager();
 //2. Query method to get a Fragment in Activity  
 fm.findFragmentById(R.id.fooler)
 fm.findFragmentByTag("tagName")
 //3. Dynamically add Fragment  
 fm.beginTransaction().add(R.id.content,contentFragment, "content" ).commit();
 //4. Replace Fragment  
 fm.beginTransaction().replace(R.id.OldFragment, newFragment).commit();
 //5. Delete Fragment  
 fm.beginTransaction().remove(R.id.myFragment).commit();
 //6. Pass data to Fragment  
 f.setArguments(Bundle) method passes data 
 

The above management Fragment code should be organized in the Activity to which the Fragment belongs. Let's take a look at the specific implementation through a case.

3. Implementation Case

First, let's take a look at the application case (as shown in the figure). When you click the first area and the second area at the bottom, the center area is switched.

Interface analysis: There are three areas: the header area TitleFragment, the center area is a FrameLayout layout that dynamically loads ContentFragment through code, and the bottom area FloorFragment

1. The layout of Activity is as follows

 RelativeLayout xmlns:android= "http://schemas.android.com/apk/res/android"  
 android:layout_width= "match_parent"  
 android:layout_height= "match_parent" >
 <fragment android:id= "@+id/fgTitle"  
 android:layout_width= "match_parent"  
 android:layout_height= "45dp"  
 android:name= "com.jereh.android.course.fragment.TitleFragment"  
 />
 <FrameLayout android:id= "@+id/content"  
 android:layout_width= "match_parent"  
 android:layout_height= "match_parent"  
 android:layout_below= "@id/fgTitle"  
 />
 <fragment android:id= "@+id/floor"  
 android:layout_width= "match_parent"  
 android:layout_height= "wrap_content"  
 android:layout_alignParentBottom= "true"  
 android:orientation= "horizontal"  
 android:name= "com.jereh.android.course.fragment.FloorFragment"  
 />
 </RelativeLayout> 
 
 Copy code
 2. FloorFragment code
 Copy code 
 
 public   class FloorFragment extends Fragment implements OnClickListener {
 @Override  
 public   void onAttach(Activity activity) {
 super .onAttach(activity); 
 
 }
 @Override  
 public View onCreateView(LayoutInflater inflater, ViewGroup container,
 Bundle savedInstanceState) {
 // TODO Auto-generated method stub  
 View view=inflater.inflate(R.layout.floor_fragment, container, false );
 LinearLayout home=(LinearLayout)view.findViewById(R.id.home);
 LinearLayout list=(LinearLayout)view.findViewById(R.id.list);
 home.setOnClickListener( this );
 list.setOnClickListener( this );
 return view;
 }
 //Define an interface that is implemented in the Activity to reduce the coupling between the Activity and the Fragment  
 public   interface OnContentFragmentListener{
 void setContentFragment(String param);
 }
 private OnContentFragmentListener onContentFragmentListener;
 public   void setOnContentFragmentListener(
 OnContentFragmentListener onContentFragmentListener) {
 this .onContentFragmentListener = onContentFragmentListener;
 }
 @Override  
 public   void onClick(View view) {
 // TODO Auto-generated method stub  
 if (onContentFragmentListener!= null ){
 switch (view.getId()){
 case R.id.home:
 //Callback mechanism, calling the method of the implementation class  
 onContentFragmentListener.setContentFragment( "Main Panel Fragment" );
 break ;
 case R.id.list:
 onContentFragmentListener.setContentFragment( "list information" );
 break ;
 }
 }
 }
 }
3. ContentFragment code

 public   class ContentFragment extends Fragment {
 private String title;
 public   void setArguments(Bundle args) {
 title=args.getString( "title" );
 }
 @Override  
 public View onCreateView(LayoutInflater inflater, ViewGroup container,
 Bundle savedInstanceState) {
 View view=inflater.inflate(R.layout.content_fragment, container, false );
 if (title!= null )((TextView)view.findViewById(R.id.tvContent)).setText(title);
 return view;
 }
 } 
 

4. DynaFragmentActivity code

 public   class DynaFragmentActivity extends FragmentActivity implements FloorFragment.OnContentFragmentListener {
 private ContentFragment contentFragment;
 private FloorFragment floor;
 @Override  
 protected   void onCreate(Bundle savedInstanceState) {
 super .onCreate(savedInstanceState);
 super .setContentView(R.layout.dyna_fragment_activity);
 initFragment();
 }
 private   void initFragment(){
 floor=(FloorFragment) super .getSupportFragmentManager().findFragmentById(R.id.floor);
 floor.setOnContentFragmentListener( this ); //Register to listen, pass in the implementation class object  
 contentFragment= new ContentFragment();
 FragmentManager fm= super .getSupportFragmentManager();
 fm.beginTransaction().add(R.id.content,contentFragment, "content" ).commit();
 } 
 
 public   void setFragment(Fragment fragment){
 getSupportFragmentManager().beginTransaction().replace(R.id.content, fragment).commit();
 } 
 
 @Override  
 public   void setContentFragment(String param) {
 // TODO Auto-generated method stub  
 Bundle bundle = new Bundle();
 bundle.putString( "title" , param);
 contentFragment= new ContentFragment();
 contentFragment.setArguments(bundle);
 super .getSupportFragmentManager().beginTransaction()
 .replace(R.id.content, contentFragment).commit();
 } 
 
 }