Android Listview中显示不同的视图布局详解及实例代码
AndroidListview中显示不同的视图布局
1.使用场景
在重写ListView的BaseAdapter时，我们常常在getView()方法中复用convertView，以提高性能。convertView在Item为单一的同种类型布局时，能够回收并重用，但是多个Item布局类型不同时，convertView的回收和重用会出现问题。比如有些行为纯文本，有些行则是图文混排，这里纯文本行为一类布局，图文混排的行为第二类布局。单一类型的ListView很简单，下面着重介绍一下ListView包含多种类型视图布局的情形。
2.ListView包含不同Item的布局
我们需要做这些工作:
1）重写getViewTypeCount()–该方法返回多少个不同的布局
2）重写getItemViewType(int)–根据position返回相应的Item
3）根据viewitem的类型，在getView中创建正确的convertView
3.案例
importjava.util.ArrayList;
importandroid.app.Activity;
importandroid.content.Context;
importandroid.os.Bundle;
importandroid.util.Log;
importandroid.view.LayoutInflater;
importandroid.view.View;
importandroid.view.ViewGroup;
importandroid.widget.BaseAdapter;
importandroid.widget.CheckBox;
importandroid.widget.ImageView;
importandroid.widget.LinearLayout;
importandroid.widget.ListView;
importandroid.widget.TextView;
publicclasslistViewTestextendsActivity{
/**Calledwhentheactivityisfirstcreated.*/
ListViewlistView;
MyAdapterlistAdapter;
ArrayList<String>listString;
@Override
publicvoidonCreate(BundlesavedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
listView=(ListView)this.findViewById(R.id.listview);
listString=newArrayList<String>();
for(inti=0;i<100;i++)
{
listString.add(Integer.toString(i));
}
listAdapter=newMyAdapter(this);
listView.setAdapter(listAdapter);
}
classMyAdapterextendsBaseAdapter{
ContextmContext;
LinearLayoutlinearLayout=null;
LayoutInflaterinflater;
TextViewtex;
finalintVIEW_TYPE=3;
finalintTYPE_1=0;
finalintTYPE_2=1;
finalintTYPE_3=2;
publicMyAdapter(Contextcontext){
//TODOAuto-generatedconstructorstub
mContext=context;
inflater=LayoutInflater.from(mContext);
}
@Override
publicintgetCount(){
//TODOAuto-generatedmethodstub
returnlistString.size();
}
//每个convertview都会调用此方法，获得当前所需要的view样式
@Override
publicintgetItemViewType(intposition){
//TODOAuto-generatedmethodstub
intp=position%6;
if(p==0)
returnTYPE_1;
elseif(p<3)
returnTYPE_2;
elseif(p<6)
returnTYPE_3;
else
returnTYPE_1;
}
@Override
publicintgetViewTypeCount(){
//TODOAuto-generatedmethodstub
return3;
}
@Override
publicObjectgetItem(intarg0){
//TODOAuto-generatedmethodstub
returnlistString.get(arg0);
}
@Override
publiclonggetItemId(intposition){
//TODOAuto-generatedmethodstub
returnposition;
}
@Override
publicViewgetView(intposition,ViewconvertView,ViewGroupparent){
//TODOAuto-generatedmethodstub
viewHolder1holder1=null;
viewHolder2holder2=null;
viewHolder3holder3=null;
inttype=getItemViewType(position);
//无convertView，需要new出各个控件
if(convertView==null)
{
Log.e("convertView=","NULL");
//按当前所需的样式，确定new的布局
switch(type)
{
caseTYPE_1:
convertView=inflater.inflate(R.layout.listitem1,parent,false);
holder1=newviewHolder1();
holder1.textView=(TextView)convertView.findViewById(R.id.textview1);
holder1.checkBox=(CheckBox)convertView.findViewById(R.id.checkbox);
Log.e("convertView=","NULLTYPE_1");
convertView.setTag(holder1);
break;
caseTYPE_2:
convertView=inflater.inflate(R.layout.listitem2,parent,false);
holder2=newviewHolder2();
holder2.textView=(TextView)convertView.findViewById(R.id.textview2);
Log.e("convertView=","NULLTYPE_2");
convertView.setTag(holder2);
break;
caseTYPE_3:
convertView=inflater.inflate(R.layout.listitem3,parent,false);
holder3=newviewHolder3();
holder3.textView=(TextView)convertView.findViewById(R.id.textview3);
holder3.imageView=(ImageView)convertView.findViewById(R.id.imageview);
Log.e("convertView=","NULLTYPE_3");
convertView.setTag(holder3);
break;
}
}else{
//有convertView，按样式，取得不用的布局
switch(type)
{
caseTYPE_1:
holder1=(viewHolder1)convertView.getTag();
Log.e("convertView!!!!!!=","NULLTYPE_1");
break;
caseTYPE_2:
holder2=(viewHolder2)convertView.getTag();
Log.e("convertView!!!!!!=","NULLTYPE_2");
break;
caseTYPE_3:
holder3=(viewHolder3)convertView.getTag();
Log.e("convertView!!!!!!=","NULLTYPE_3");
break;
}
}
//设置资源
switch(type)
{
caseTYPE_1:
holder1.textView.setText(Integer.toString(position));
holder1.checkBox.setChecked(true);
break;
caseTYPE_2:
holder2.textView.setText(Integer.toString(position));
break;
caseTYPE_3:
holder3.textView.setText(Integer.toString(position));
holder3.imageView.setBackgroundResource(R.drawable.icon);
break;
}
returnconvertView;
}
}
//各个布局的控件资源
classviewHolder1{
CheckBoxcheckBox;
TextViewtextView;
}
classviewHolder2{
TextViewtextView;
}
classviewHolder3{
ImageViewimageView;
TextViewtextView;
}
}
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