13-4-1 Android中list和Adapter的使用

Android中list和Adapter的使用

java.util.List<E>

包含有：

AbstractList<E>,AbstractSequentialList<E>,ArrayList<E>,CopyOnWriteArrayList<E>,LinkedList<E>,Stack<E>,Vector<E>

privateList<ChatMessage>messages=newArrayList<ChatMessage>();

ChatMessage为数据列表

privateChattingAdapterchatHistoryAdapter;

chatHistoryAdapter为数据源也就是listview和数据列表的桥梁。

1、ChatMessage类定义

packagecn.itcast.test.chat.adapter;

publicclassChatMessage{

publicstaticfinalintMESSAGE_FROM=0;

publicstaticfinalintMESSAGE_TO=1;

privateintdirection;

privateStringcontent;

publicChatMessage(intdirection,Stringcontent){

super();

this.direction=direction;

this.content=content;

}

publicintgetDirection(){

returndirection;

}

publicvoidsetDirection(intdirection){

this.direction=direction;

}

publicvoidsetContent(Stringcontent){

this.content=content;

}

publicCharSequencegetContent(){

returncontent;

}

2.ChattingAdapter类定义

packagecn.itcast.test.chat.adapter;

importjava.util.List;

importcn.itcast.test.chat.R;

importandroid.content.Context;

importandroid.view.LayoutInflater;

importandroid.view.View;

importandroid.view.ViewGroup;

importandroid.widget.BaseAdapter;

importandroid.widget.TextView;

publicclassChattingAdapterextendsBaseAdapter{

protectedstaticfinalStringTAG="ChattingAdapter";

privateContextcontext;

privateList<ChatMessage>chatMessages;//关联数据

//析构函数

publicChattingAdapter(Contextcontext,List<ChatMessage>messages){

super();

this.context=context;

this.chatMessages=messages;

}

@Override

publicintgetCount(){//返回数据源中总的记录数目

returnchatMessages.size();

}

@Override

publicObjectgetItem(intposition){//获得选择的数据源中某个项目的数据

returnchatMessages.get(position);

}

@Override

publiclonggetItemId(intposition){//获取数据源中的索引值

returnposition;

}

@Override//获取要展示的项目View对象

publicViewgetView(intposition,ViewconvertView,ViewGroupparent){

ViewHolderholder=null;

ChatMessagemessage=chatMessages.get(position);

if(convertView==null||(holder=(ViewHolder)convertView.getTag()).flag!=message.getDirection()){

holder=newViewHolder();

if(message.getDirection()==ChatMessage.MESSAGE_FROM){

holder.flag=ChatMessage.MESSAGE_FROM;

convertView=LayoutInflater.from(context).inflate(R.layout.chatting_item_from,null);

}else{

holder.flag=ChatMessage.MESSAGE_TO;

convertView=LayoutInflater.from(context).inflate(R.layout.chatting_item_to,null);

}

holder.text=(TextView)convertView.findViewById(R.id.chatting_content_itv);

convertView.setTag(holder);

}

holder.text.setText(message.getContent());

returnconvertView;

}

//优化listview的Adapter

staticclassViewHolder{

TextViewtext;

intflag;

}

3主程序中的初始化调用

//设置adapter

privatevoidsetAdapterForThis(){

initMessages();

chatHistoryAdapter=newChattingAdapter(this,messages);

chatHistoryLv.setAdapter(chatHistoryAdapter);

}

//为listView添加数据

privatevoidinitMessages(){

messages.add(newChatMessage(ChatMessage.MESSAGE_FROM,"hello"));

messages.add(newChatMessage(ChatMessage.MESSAGE_TO,"hello"));

messages.add(newChatMessage(ChatMessage.MESSAGE_FROM,"welcomemeblog:http://blog.csdn.net/feiyangxiaomi"));

}

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飞扬小米（记）

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