Display different view la s in listview

1. Use Cases

InBaseadapter, we often reuse convertview in the getview () method to improve performance.ConvertviewInItemFor a single layout of the same type, it can be recycled and reused, but multipleItemDifferent layout types,ConvertviewThere will be problems with the collection and reuse. For example, some behaviors are plain text, while some rows are text-and-text mixing. Here, the pure text behavior is a type of layout, and the text-and-text mixing behavior is a type of second layout. A single type of listview is very simple. The following describes the situation that listview contains multiple types of view la S.

 

2. listview contains layout of different items

We need to do the following:

1) override getviewtypecount ()-the number of different la s returned by this method

2) override getitemviewtype (INT)-return the corresponding item according to position

3) Create the correct convertview in getview Based on The View Item type.

 

3. Case studies

 Import Java. util. arraylist;  Import  Android. App. activity;  Import  Android. content. context;  Import  Android. OS. Bundle;  Import  Android. util. log;  Import  Android. View. layoutinflater;  Import  Android. View. view;  Import  Android. View. viewgroup; Import  Android. widget. baseadapter;  Import  Android. widget. checkbox;  Import  Android. widget. imageview;  Import  Android. widget. linearlayout;  Import  Android. widget. listview;  Import  Android. widget. textview;  Public   Class ListviewtestExtends  Activity {  /**  Called when the activity is first created.  */  Listview; myadapter listadapter; arraylist <String> Liststring; @ override  Public   Void  Oncreate (bundle savedinstancestate ){  Super  . Oncreate (savedinstancestate); setcontentview (R. layout. Main); listview = (Listview)This  . Findviewbyid (R. Id. listview); liststring = New Arraylist <string> ();  For ( Int I = 0; I <100; I ++ ) {Liststring. Add (integer. tostring (I);} listadapter = New Myadapter ( This  ); Listview. setadapter (listadapter );}  Class Myadapter Extends Baseadapter {context mcontext; linearlayout = Null  ; Layoutinflater Inflater; textview Tex;  Final   Int View_type = 3 ;  Final   Int Type_1 = 0 ;  Final   Int Type_2 = 1 ;  Final   Int Type_3 = 2 ;  Public  Myadapter (context ){  //  Todo auto-generated constructor stub Mcontext = Context; Inflater = Layoutinflater. From (mcontext);} @ override  Public   Int  Getcount (){  //  Todo auto-generated method stub  Return Liststring. Size ();}  //  This method is called for each convert view to obtain the currently required view style.  @ Override  Public   Int Getitemviewtype ( Int  Position ){  //  Todo auto-generated method stub  Int P = position % 6 ;  If (P = 0)  Return  Type_1;  Else   If (P <3 )  Return  Type_2;  Else   If (P <6 )  Return  Type_3;  Else  Return Type_1;} @ override  Public   Int  Getviewtypecount (){  //  Todo auto-generated method stub  Return 3 ;} @ Override  Public Object getitem ( Int  Arg0 ){  //  Todo auto-generated method stub  Return Liststring. Get (arg0) ;}@ override  Public   Long Getitemid ( Int  Position ){  //  Todo auto-generated method stub  Return  Position ;}@ override  Public View getview ( Int  Position, view convertview, viewgroup parent ){  // Todo auto-generated method stub Viewholder1 holder1 = Null  ; Viewholder2 holder2 = Null  ; Viewholder3 holder3 = Null  ;  Int Type = Getitemviewtype (position );  //  No convertview, new controls are required  If (Convertview = Null ) {Log. E ( "Convertview =", "null" );  //  Determine the new layout based on the current style.  Switch  (Type ){  Case  Type_1: convertview = Inflater. Inflate (R. layout. listitem1, parent, False  ); Holder1 = New  Viewholder1 (); holder1.textview =(Textview) convertview. findviewbyid (R. Id. textview1); holder1.checkbox = (Checkbox) convertview. findviewbyid (R. Id. checkbox); log. E ( "Convertview =", "null type_1" ); Convertview. settag (holder1 );  Break  ;  Case  Type_2: convertview = Inflater. Inflate (R. layout. listitem2, parent, False  ); Holder2 = New Viewholder2 (); holder2.textview = (Textview) convertview. findviewbyid (R. Id. textview2); log. E ( "Convertview =", "null type_2" ); Convertview. settag (holder2 );  Break  ;  Case  Type_3: convertview = Inflater. Inflate (R. layout. listitem3, parent, False  ); Holder3 = New  Viewholder3 (); holder3.textview =(Textview) convertview. findviewbyid (R. Id. textview3); holder3.imageview = (Imageview) convertview. findviewbyid (R. Id. imageview); log. E ( "Convertview =", "null type_3" ); Convertview. settag (holder3 );  Break  ;}}  Else  {  //  Convertview and style-based layout for unused la s  Switch  (Type ){  Case Type_1: holder1 = (Viewholder1) convertview. gettag (); log. E ( "Convertview !!!!!! = "," Null type_1" );  Break  ;  Case  Type_2: holder2 = (Viewholder2) convertview. gettag (); log. E ( "Convertview !!!!!! = "," Null type_2" );  Break  ;  Case Type_3: holder3 = (Viewholder3) convertview. gettag (); log. E ( "Convertview !!!!!! = "," Null type_3" );  Break  ;}}  //  Set Resources  Switch  (Type ){  Case  Type_1: holder1.textview. settext (integer. tostring (position); holder1.checkbox. setchecked (  True );  Break  ;  Case  Type_2: holder2.textview. settext (integer. tostring (position ));  Break  ;  Case  Type_3: holder3.textview. settext (integer. tostring (position); holder3.imageview. setbackgroundresource (R. drawable. Icon );  Break  ;}  Return  Convertview ;}} //  Control resources for various la s  Class  Viewholder1 {checkbox; textview ;}
  Class  Viewholder2 {textview ;}
  Class  Viewholder3 {imageview; textview ;}}