Android开发之利用ListView动态刷新某个Item

前言

本文实现的是使用viewholder来刷新某项数据，而不用每次都全部刷新数据。下面话不多说，来看看详细的介绍。

实现方法

继承baseadapter，新建viewholder类。

public class testlistadapter extends baseadapter { 
 private context mcontext; 
 
 private list<string> strlist; 
 
 public testlistadapter(context context, list<string> list) { 
  super(); 
  this.mcontext = context; 
  this.strlist = list; 
 } 
 
 @override 
 public int getcount() { 
  // todo auto-generated method stub 
  return strlist.size(); 
 } 
 
 @override 
 public object getitem(int position) { 
  // todo auto-generated method stub 
  return position; 
 } 
 
 @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 
  viewholder holder = null; 
  if (null == convertview) { 
   convertview = layoutinflater.from(mcontext).inflate(r.layout.line, null); 
 
   holder = new viewholder(); 
   holder.idtext = (textview) convertview.findviewbyid(r.id.textview_id); 
   holder.strtext = (textview) convertview.findviewbyid(r.id.textview_str); 
 
   convertview.settag(holder); 
  } else { 
   holder = (viewholder) convertview.gettag(); 
  } 
 
  holder.idtext.settext(position + ""); 
  string str = strlist.get(position); 
  holder.strtext.settext(str); 
 
  return convertview; 
 } 
 
 private static class viewholder { 
  private textview idtext; 
 
  private textview strtext; 
 } 
 
 public void updataview(int posi, listview listview) { 
  int visiblefirstposi = listview.getfirstvisibleposition(); 
  int visiblelastposi = listview.getlastvisibleposition(); 
  if (posi >= visiblefirstposi && posi <= visiblelastposi) { 
   view view = listview.getchildat(posi - visiblefirstposi); 
   viewholder holder = (viewholder) view.gettag(); 
 
   string txt = holder.strtext.gettext().tostring(); 
   txt = txt + "++;"; 
   holder.strtext.settext(txt); 
   strlist.set(posi, txt); 
  } else { 
   string txt = strlist.get(posi); 
   txt = txt + "++;"; 
   strlist.set(posi, txt); 
  } 
 } 
} 

在activity中，调用updateview()方法，刷新数据。

public class mainactivity extends activity { 
 private mainactivity mcontext; 
 
 private edittext idedit; 
 
 private textview textview; 
 
 private list<string> strlist = new arraylist<string>(); 
 private listview listview; 
 private testlistadapter listadapter; 
 @override 
 protected void oncreate(bundle savedinstancestate) { 
  super.oncreate(savedinstancestate); 
  setcontentview(r.layout.activity_main); 
 
  mcontext = this; 
 
  for (int i = 0; i < 100; i++) { 
   strlist.add("test data"); 
  } 
 
  idedit = (edittext) findviewbyid(r.id.edittext_id); 
  textview = (textview) findviewbyid(r.id.textview_modify); 
 
  listview = (listview) findviewbyid(r.id.listview); 
  listadapter = new testlistadapter(mcontext, strlist); 
  listview.setadapter(listadapter); 
 
  //动态刷新 
  textview.setonclicklistener(new onclicklistener() { 
 
   @override 
   public void onclick(view v) { 
    // todo auto-generated method stub 
    string idstr = idedit.gettext().tostring(); 
    int idint = integer.parseint(idstr); 
    listadapter.updataview(idint, listview);//动态修改 
   } 
  }); 
 } 
} 

给出布局文件：

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 android:background="#ffffff" 
 android:orientation="vertical" > 
 
 <linearlayout 
  android:layout_width="match_parent" 
  android:layout_height="40dp" 
  android:orientation="horizontal" > 
 
  <edittext 
   android:id="@+id/edittext_id" 
   android:layout_width="200dp" 
   android:layout_height="wrap_content" 
   android:hint="put modify id" /> 
 
  <textview 
   android:id="@+id/textview_modify" 
   android:layout_width="wrap_content" 
   android:layout_height="wrap_content" 
   android:text="动态修改" 
   android:textcolor="#123456" /> 
 </linearlayout> 
 
 <listview 
  android:id="@+id/listview" 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" > 
 </listview> 
 
</linearlayout> 

总结

以上就是这篇文章的全部内容了，希望本文的内容对大家的学习或者工作能带来一定的帮助，如果有疑问大家可以留言交流。