Android ListView Optimizer

Android ListView optimizations are implemented by reusing the historical cache. The data adapter for the ListView typically uses a custom baseadapter subclass to reuse the historical cache to improve performance. The sample code is as follows:

1. ListView Data Adapter

/** * Data adapter class for pending leave information * @author YQQ * */private class Leaveinfoadapter extends baseadapter{@Overridepublic int GetCount () {//TODO auto-generated method Stubreturn mleaveinfos.size ();} @Overridepublic Object getItem (int position) {//TODO auto-generated method Stubreturn mleaveinfos.get (position);} @Overridepublic long Getitemid (int position) {//TODO auto-generated method Stubreturn position;} @Overridepublic view GetView (int position, view Convertview, ViewGroup parent) {view view=null; Viewholder holder=null;if (convertview!=null && convertview instanceof linearlayout) {View=convertview;holder = (Viewholder) View.gettag ();} Else{view=view.inflate (Getapplicationcontext (), r.layout.leave_info_item, null); holder=new ViewHolder (); Holder.name= (TextView) View.findviewbyid (r.id.tv_name); holder.workidanddepartment= (TextView) View.findviewbyid ( R.id.tv_workid_depart); holder.leaveinfo= (TextView) View.findviewbyid (r.id.tv_leave_info); holder.date= (TextView) View.findviewbyid (r.id.tv_date); holder.enDdate= (TextView) View.findviewbyid (r.id.tv_endtime); View.settag (holder);} Leaveinfo Info=mleaveinfos.get (position); LOG.I ("Test", info.tostring ()); Holder.name.setText (Info.getname ()); Holder.workIdAndDepartment.setText ("(Work No.:" + Info.getworkid () + "department:" +info.getdepartment () + ")"); Holder.leaveinfo.setText (Info.getleaveinfo ()); Holder.date.setText ("Holidays:" +info.getleavedata () + "\ n"), Holder.endDate.setText ("-" +info.getendleavedate ()); return view;}} private static class Viewholder{textview name;//Employee name Display Control TextView workidanddepartment;//employee work number and department display TextView leaveinfo;/ /employee Leave Information TextView date;//employee leave date TextView endDate;}

2. Layout of each data display

Leave_info_item.xml

<?xml version= "1.0" encoding= "Utf-8"? ><linearlayout xmlns:android= "http://schemas.android.com/apk/res/       Android "Android:layout_width=" Match_parent "android:layout_height=" match_parent "android:orientation=" vertical " > <linearlayout android:layout_width= "match_parent" android:layout_height= "Match_parent" a        ndroid:orientation= "Horizontal" > <imageview android:id= "@+id/iv_headcolor"             Android:layout_width= "Wrap_content" android:layout_height= "80DP" android:src= "@drawable/light_green"/> <relativelayout android:layout_width= "match_parent" android:layout_height= "Ma                Tch_parent "android:layout_marginleft=" 5DP "android:layout_margintop=" 5DP ">                    <textview android:id= "@+id/tv_name" android:layout_width= "Wrap_content" android:layout_height="Wrap_content" android:text= "name" android:textcolor= "#ff0000" Android                    Oid:textsize= "15sp"/> <textview android:id= "@+id/tv_leave_info" Android:layout_width= "Wrap_content" android:layout_height= "Wrap_content" android:l                    ayout_below= "@+id/tv_name" android:paddingtop= "8DP" android:text= "Reason for leave"                    Android:textsize= "20sp"/> <textview android:id= "@+id/tv_date" Android:layout_width= "Wrap_content" android:layout_height= "Wrap_content" Android Oid:layout_above= "@+id/tv_leave_info" android:layout_alignparentright= "true" Android                 : text= "Date" android:textcolor= "#000000" android:textsize= "10sp"/>           <textview         Android:id= "@+id/tv_endtime" android:layout_width= "Wrap_content" Android:la yout_height= "Wrap_content" android:layout_below= "@+id/tv_date" Android:                    Layout_alignparentright= "true" android:text= "date 2" android:textcolor= "#000000" Android:textsize= "10sp"/> <textview android:id= "@+id/tv_workid_depar                    T "android:layout_width=" wrap_content "android:layout_height=" Wrap_content "                    Android:layout_alignparenttop= "true" android:layout_torightof= "@+id/tv_name" Android:gravity= "Center_horizontal" android:paddingleft= "5DP" android:text= "name and department                           Door "android:textcolor=" #0000ff "android:textsize=" 13sp "/> </relativelayout&gT        </LinearLayout> <view android:layout_width= "match_parent" android:layout_height= "2DP" android:background= "@android:d Rawable/divider_horizontal_dark"/></linearlayout>

3. Loading data with asynchronous tasks

/** * Fill pending leave information using asynchronous load data listview */private void Filldata () {new asynctask<void,void,void> () {@Overrideprotected void OnPostExecute (void result) {if (madapter==null) {madapter=new leaveinfoadapter ();// Set data adapter Mlvleaveinfos.setadapter (Madapter); LOG.I ("Test", "asynchronous task shows background data for database");} else {madapter.notifydatasetchanged ();} Super.onpostexecute (result);} @Overrideprotected void Doinbackground (void ... params) {//Get the data to be displayed Mleaveinfos=mleaveinfosdao.findall (); Mleaveinfos==null) {Toast.maketext (homeactivity.this), "Leave data does not exist or has been cleared!" ",". Show ();} LOG.I ("Test", "asynchronous task backend obtains database data" +mleaveinfos.size ()); return null;}}. Execute ();}

4, for the list of each binding event monitoring

Mlvleaveinfos.setonitemclicklistener (New Onitemclicklistener () {@Overridepublic void Onitemclick (adapterview<? > Parent, View view,int position, long id) {Object object=mlvleaveinfos.getitematposition (position); LOG.I ("Consent test", object+ ""); if (object instanceof leaveinfo) {tmpinfo= (Leaveinfo) object; LOG.I ("Consent Test", tmpinfo.tostring ()); Showacceptorno ();}});

5, the list of other listening and paging load for local data does not require paging, for server-side data should be paged load save traffic.

Drop-down list when the paging load data Mrubishsms.setonscrolllistener (new Onscrolllistener () {@Overridepublic void onscrollstatechanged ( Abslistview view, int scrollstate) {switch (scrollstate) {//Show data case when the drop-down list is idle onscrolllistener.scroll_state_idle:// Gets the maximum per page load for a paginated int position=mrubishsms.getlastvisibleposition (); int total=0;if (minfos!=null) {//total=maxnum;total= Minfos.size ();} if (POSITION==TOTAL-1) {//arrives at the end of the page load Offset+=maxnum;if (offset>totalnums) {Toast.maketext ( Rubishsmsactivity.this, "The data has been loaded, no more data ...". Show (); return;} Asynchronous task Load Data Filldata ();} Break;}} @Overridepublic void Onscroll (abslistview view, int firstvisibleitem,int visibleitemcount, int totalitemcount) {//TODO A uto-generated method stub}}); Filldata ();//per-entry binding listener Mrubishsms.setonitemclicklistener (new Onitemclicklistener () { View m_view=view.inflate (rubishsmsactivity.this,r.layout.show_rubish_sms_operation,null); @Overridepublic void Onitemclick (adapterview<?> parent, View view,int position, long ID) {//Get an entry corresponding to each object of objects Object=mrubishsms.geTitematposition (position); if (object instanceof Rubishsmsinfo) {final rubishsmsinfo info= (rubishsmsinfo) object;// Action on the object 1, delete 2, restore to Inbox 3, blacklist Dialog builder=new Dialog (rubishsmsactivity.this); Builder.settitle ("hint"); Builder.setcontentview (M_view);//Delete ((TextView) M_view.findviewbyid (R.id.tv_delete)). Setonclicklistener (New Onclicklistener () {@Overridepublic void OnClick (View v) {minfos.remove (info); if (mrubishsmsinfodao==null) { Mrubishsmsinfodao=new Rubishsmsinfodao (Getapplicationcontext ());} Mrubishsmsinfodao.deletesmsinfos (Info), if (madapter==null) {madapter=new rubishsmsinfosadapter (); Mrubishsms.setadapter (Madapter);} Else{madapter.notifydatasetchanged ();}}); /Revert to Inbox ((TextView) M_view.findviewbyid (r.id.tv_recovery_sms)). Setonclicklistener (New Onclicklistener () {@ overridepublic void OnClick (View v) {}});//blacklist ((TextView) M_view.findviewbyid (R.id.tv_add_black_number)). Setonclicklistener (New Onclicklistener () {@Overridepublic void OnClick (View v) {}}); Builder.show ();}});}

6. Baseexpandablelistadapter Sample Demo:

public class Commonnumberactivity extends Activity {private Expandablelistview elv;private list<string> Groupnames;private Map<integer, list<string>> Childrencacheinfos; @Overrideprotected void OnCreate ( Bundle savedinstancestate) {super.oncreate (savedinstancestate); Childrencacheinfos = new Hashmap<integer, List< String>> (); Setcontentview (r.layout.activity_common_num); ELV = (Expandablelistview) Findviewbyid (R.ID.ELV); Elv.setadapter (New Myadapter ()); Elv.setonchildclicklistener (new Onchildclicklistener () {@Overridepublic Boolean Onchildclick (expandablelistview parent, View v,int groupposition, int childposition, long id) {Intent Intent = new Intent ( ); Intent.setaction (intent.action_dial); String number = Childrencacheinfos.get (groupposition). Get (Childposition). Split ("\ n") [1];intent.setdata (Uri.parse ( "Tel:" +number)); StartActivity (intent); return false;}); Private class Myadapter extends Baseexpandablelistadapter {//returns the number of groupings @overridepublic int GetGroupCount () {//REturn Commonnumdao.getgroupcount (); groupnames = Commonnumdao.getgroupinfos (); return groupnames.size ();} @Overridepublic int getchildrencount (int groupposition) {//0 start list<string> childreninfos;if ( Childrencacheinfos.containskey (groupposition)) {Childreninfos = Childrencacheinfos.get (groupPosition);} else { Childreninfos = Commonnumdao.getchildreninfosbyposition (groupposition); Childrencacheinfos.put (GroupPosition, Childreninfos);} return Childreninfos.size ();} @Overridepublic Object getgroup (int groupposition) {return null;} @Overridepublic Object getchild (int groupposition, int childposition) {return null;} @Overridepublic long getgroupid (int groupposition) {return 0;} @Overridepublic long Getchildid (int groupposition, int childposition) {return 0;} @Overridepublic Boolean hasstableids () {return false;} @Overridepublic View getgroupview (int groupposition, Boolean Isexpanded,view Convertview, ViewGroup parent) {TextView TV if (Convertview!=null&&convertview instanceof TextView) {TV = (TextView) Convertview;} ELSE{TV = new TextView (Getapplicationcontext ());} Tv.settextsize (+); Tv.settextcolor (color.red);//Tv.settext ("" +commonnumdao.getgroupname (groupposition)); Tv.settext ("" + Groupnames.get (groupposition)); return TV;} @Overridepublic view Getchildview (int groupposition, int childposition,boolean islastchild, view Convertview, ViewGroup Parent) {TextView tv;if (convertview!=null&&convertview instanceof TextView) {TV = (TextView) Convertview;} ELSE{TV = new TextView (Getapplicationcontext ());} Tv.settextsize, Tv.settextcolor (Color.Blue);//tv.settext (Commonnumdao.getchildinfobyposition, childposition)); Tv.settext (Childrencacheinfos.get (groupposition). Get (Childposition)); return TV;} @Overridepublic boolean ischildselectable (int groupposition, int childposition) {return true;}}}

7. Another usage of Baseadapter data adapter Demo:

Package Com.example.yqqmobilesafe;import Com.example.yqqmobilesafe.cleanache.cleancacheactivity;import Android.app.activity;import Android.content.intent;import Android.os.bundle;import Android.util.Log;import Android.view.view;import Android.view.viewgroup;import Android.widget.adapterview;import Android.widget.adapterview.onitemclicklistener;import Android.widget.baseadapter;import Android.widget.GridView; Import Android.widget.imageview;import Android.widget.linearlayout;import Android.widget.textview;public class Oftenusefunctionactivity extends Activity {private Boolean d=true; private GridView mgridview;//common features show private gvadapter  Madapter; Private string[] items={"cleanup acceleration", "Charge Flow", "Harassment interception", "anti-suction fee", "Pay Bodyguard", "mobile phone Antivirus"}; Private int[] Icons={r.drawable.exam_frequently_used_tools_icon_clean,r.drawable.exam_frequently_used_tools_icon _net_traffic,r.drawable.exam_frequently_used_tools_icon_block_anoy,r.drawable.exam_frequently_used_tools_icon_ Costguard,r.drawable.exam_frequently_used_tools_icon_guarDpay,r.drawable.exam_frequently_used_tools_icon_malware};p ublic oftenusefunctionactivity () {//TODO Auto-generated constructor stub} @Overrideprotected void OnCreate (Bundle savedinstancestate) {//TODO auto-generated method Stubsuper.oncreate (savedinstancestate); Setcontentview (r.layout.activity_tab_often_use_function);// Data adaptation mgridview= (GridView) This.findviewbyid (r.id.gv_home); madapter=new gvadapter (); Mgridview.setadapter (MAdapter)  ; Setlistener ();} private void Setlistener () {Mgridview.setonitemclicklistener (new Onitemclicklistener () {@Overridepublic void Onitemclick (adapterview<?> parent, View view,int position, long ID) {switch (position) {case 0:intent intent=new int ENT (Oftenusefunctionactivity.this,cleancacheactivity.class); startactivity (intent); if (D) {log.i (" Oftenusefunctionactivity "," cleanup Acceleration ");} Break;case 1:if (D) {log.i ("oftenusefunctionactivity", "Telephone Traffic");} Break;case 2:if (D) {log.i ("oftenusefunctionactivity", "harassment interception"); Intent intent2=new Intent (oftenusefunctionactivity.this,stopanonyActivity.class); startactivity (Intent2); Break;case 3:if (D) {log.i ("oftenusefunctionactivity", "anti-suction fee");} Break;case 4:if (D) {log.i ("oftenusefunctionactivity", "Payment bodyguard"); Break;case 5:intent intent6=new Intent (oftenusefunctionactivity.this,killvirusactivity.class); StartActivity ( INTENT6), if (D) {log.i ("oftenusefunctionactivity", "mobile Antivirus");}  Break;}} });} Data adapter with function Private class Gvadapter extends baseadapter{@Overridepublic int GetCount () {//TODO auto-generated method Stubreturn Items.length;} @Overridepublic Object getItem (int position) {//TODO auto-generated method Stubreturn null;} @Overridepublic long Getitemid (int position) {//TODO auto-generated method Stubreturn position;} @Overridepublic view GetView (int position, view Convertview, ViewGroup parent) {View View=view.inflate ( Oftenusefunctionactivity.this,r.layout.home_item,null); ImageView ivicon= (ImageView) View.findviewbyid (R.id.iv_ Home_icon); TextView tvfunname= (TextView) View.findviewbyid (r.id.tv_home_function_name); Ivicon.setimageresource (Icons[position]); Tvfunname.settext (Items[position]); return view;} } static class viewholder{ImageView ivicon;//function icon TextView tvfunname;//function Description}}

Home_item.xml

<?xml version= "1.0" encoding= "Utf-8"? ><linearlayout xmlns:android= "http://schemas.android.com/apk/res/ Android "    android:layout_width=" wrap_content "    android:layout_height=" 95DP "    android:gravity=" center "    android:background= "@drawable/grid_selector" >    <imageview        android:layout_margintop= "5DP"        android:id= "@+id/iv_home_icon"        android:layout_width= "55DP"        android:layout_height= "45DP"       / >    <textview        android:layout_margintop= "5DP"        android:id= "@+id/tv_home_function_name"        Android:layout_width= "Wrap_content"        android:layout_height= "wrap_content"        android:layout_marginright= "10DP"        android:gravity= "center_vertical"              android:textcolor= "#000000"        android:textsize= "20SP"/ ></LinearLayout>

Android ListView Optimizer