MU Class Network Universal Adapter Learning Notes

First of all, thank you again for the technology of the network, Daniel shared the course.

A. Traditional mode of the ListView adapter: 1. Create a ListView and create the item layout for the ListView 2. Encapsulating Data 3. Create a specific adapter for the item layout for data presentation. (In this process, if there are too many controls in a ListView item, the life and invocation of the control will cause the code to rise, and if there are many places in an app that need to be used in a ListView, writing multiple adapters separately can lead to many repetitive operations, In order to avoid this situation, make coding easier, you can refer to Mu-class network Android Universal adapter writing. ）。

The traditional adapter coding style is as follows:

 PackageCom.imooc.imooc_adapter;Importjava.util.List;ImportAndroid.content.Context;ImportAndroid.view.LayoutInflater;ImportAndroid.view.View;ImportAndroid.view.ViewGroup;ImportAndroid.widget.BaseAdapter;ImportAndroid.widget.TextView; Public classMyadapterextendsBaseadapter {Privatecontext Context; PrivateList<bean>mlist;  PublicMyadapter (context context, list<bean>mlist) {        Super();  This. Context =context;  This. mlist =mlist; }         PublicList<bean>getmlist () {returnmlist; }     Public voidSetmlist (list<bean>mlist) {         This. mlist =mlist; } @Override Public intGetCount () {returnmlist.size (); } @Override PublicObject GetItem (intarg0) {        returnMlist.get (arg0); } @Override Public LongGetitemid (intarg0) {        returnarg0; } @Override PublicView GetView (intposition, View Convertview, ViewGroup parent) {Viewholer Holder=NULL; if(Convertview = =NULL) {Holder=NewViewholer (); Convertview=( (layoutinflater) context. Getsystemservice (Context.layout_inflater_service)). Inflate (R.layout.item, parent,false); Holder.name=(TextView) Convertview.findviewbyid (r.id.name); Holder.phone=(TextView) Convertview.findviewbyid (R.id.phone);        Convertview.settag (holder); }Else{convertview.settag (holder); }        FinalBean Bean =Mlist.get (position);        Holder.name.setText (Bean.getusername ());        Holder.phone.setText (Bean.getphone ()); returnConvertview; }    classviewholer{TextView name;    TextView phone; }    }

The universal adapter code is as follows:

Package Com.imooc.imooc_adapter;import Java.util.list;import Android.content.context;import Com.imooc.util.commonadapter;import Com.imooc.util.viewholder;public class Newadapter  extends CommonAdapter <bean>{public Newadapter (Context context, list<bean> Mdatas,int LayoutID) {Super (context, Mdatas,layoutid );} @Overridepublic void Convert (viewholder holder, bean Bean) {holder.settext (R.id.phone, Bean.getphone ()). SetText ( R.id.name, Bean.getusername ());}}

This shows that the universal adapter can be reduced the amount of code.

The universal adapter encapsulates user-defined Viewholder and Baseadapter declarations, and calls Commonadapter and Viewholer two classes.

Universal Adapter Authoring Logic:

1. Package Viewholder, free the view Convertview, implement a code to complete the instantiation of the Convertview:

Viewholder holder = Viewholder.get (Mcontext, Convertview, parent, postion, LayoutID);

Implementation method:

public class Viewholder {private sparsearray<view> mviews;private Context mcontext;private View Mconvertview; private int mposition;public View Getmconvertview () {return mconvertview;} public int getmposition () {return mposition;} Public Viewholder (Context context, viewgroup parent, int layoutid,int position) {this.mposition = Position;this.mviews = n EW sparsearray<view> (); Mconvertview = Layoutinflater.from (context). Inflate (LayoutID, parent,false); Mconvertview.settag (this);} public static Viewholder Get (context context, View convertview,viewgroup parent, int position, int layoutid) {if (CONVERTV Iew = = null) {return new Viewholder (context, parent, layoutid, position);} else {Viewholder holder = (viewholder) CONVERTV Iew.gettag (); holder.mposition = Position;return holder;}} Public <t extends view> T getView (int viewid) {View view = Mviews.get (Viewid); if (view = = null) {view = Mconvertview . Findviewbyid (Viewid); Mviews.put (Viewid, view);} Return (T) view;}

The use of Sparearray here is similar to the:list<int,object> form of storage, to compare hashmap<int,object> to save time and improve efficiency.

To create an abstract class Commonadapter:

Public abstract class Commonadapter<t> extends Baseadapter {protected Context mcontext;protected list<t> mdatas;protected layoutinflater minlater;private int layoutid;public commonadapter (Context context,list<t> Datas,int layoutid) {this.mcontext = context;this.mdatas= Datas;this.layoutid = Layoutid;minlater = LayoutInflater.from (context);} Public Context Getmcontext () {return mcontext;} public void Setmcontext (Context mcontext) {this.mcontext = Mcontext;} Public list<t> Getmdatas () {return mdatas;} public void Setmdatas (list<t> mdatas) {this.mdatas = Mdatas;} @Overridepublic int GetCount () {return mdatas.size ();} @Overridepublic T getItem (int arg0) {return mdatas.get (arg0);} @Overridepublic long getitemid (int arg0) {return arg0;} @Overridepublic view GetView (int postion, view Convertview, ViewGroup parent) {Viewholder holder = Viewholder.get (Mcontex T, Convertview, parent, postion, LayoutID); convert (holder, GetItem (postion)); return Holder.getmconvertview ();}; PublIC abstract void convert (Viewholder holder,t T);} 

Open the Convert method to the developer for a simple assignment operation.

Inherit the Commonadapter in the custom adapter:

public class Newadapter  extends commonadapter<bean>{public    newadapter (context context, List<bean > Mdatas,int layoutid) {        Super (context, Mdatas,layoutid);    }    @Override public    void convert (viewholder holder, bean Bean) {        holder.settext (R.id.phone, Bean.getphone ()). SetText (R.id.name, Bean.getusername ());}    }

When you initialize a custom adapter in mainactivity, you can use:

New Newadapter (Getapplicationcontext (), Mlist,r.layout.item);

Where you can encapsulate the operation of a control in a adapter in a Viewholder wrapper class

 Public Viewholder setText (int  viewId, String text) {        = GetView (viewId);        Tv.settext (text);         return  This ;    }  Public Viewholder setimageresource (int viewId,int  resId) {        ImageView img=  GetView (viewId);        Img.setimageresource (resId);         return  This ;            }

Examples are as above.

MU Class Network Universal Adapter Learning Notes