ListView和Adapter使用详解

ListView其实就是一个用列表形式来展示数据的View

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根据适配器adapter的不同可以实现不同的效果：

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比如 丑得要命的：

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聊天撩妹的：

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还有这种

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嘻嘻

让我们来看一下最简单的Listview+Arrayadapter

布局：

<?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"    ><ListView            android:id="@+id/listview"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:divider="#d8d8d8"            android:dividerHeight="1dp">        </ListView> </LinearLayout>

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ListView.class:

public class ListView extends Activity{     private ListView listView;     protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);        listView= (ListView)findViewById(R.id.listview);        listView.setAdapter(new ArrayAdapter<String>(getContext(), android.R.layout.simple_list_item_1,getData()));        setContentView(listView);     }      private List<String> getData(){        List<String> data=new ArrayList<String>();        data.add("我是爷爷");        data.add("我是爸爸");        data.add("我是哥哥");        data.add("那我是谁");        return data;    }}

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效果：

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ListView+BaseAdapter

这个稍微复杂一点，需要自定义布局文件

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item.xml:

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="match_parent"    android:layout_height="match_parent">    <ImageView        android:layout_margin="8dp"        android:id="@+id/user_face"        android:layout_width="46dp"        android:layout_height="46dp" />    <TextView        android:text="234555566"        android:textColor="#111111"        android:textSize="18dp"        android:id="@+id/user_text"        android:layout_marginTop="12dp"        android:layout_marginLeft="2dp"        android:layout_toRightOf="@id/user_face"        android:layout_width="wrap_content"        android:layout_height="wrap_content" />    <TextView        android:text="123456"        android:textColor="#a1a1a1"        android:id="@+id/user_message"        android:layout_marginLeft="2dp"        android:layout_below="@id/user_text"        android:layout_toRightOf="@id/user_face"        android:layout_width="wrap_content"        android:layout_height="wrap_content" />    <TextView        android:text="11:30"        android:textColor="#a1a1a1"        android:padding="12dp"        android:id="@+id/user_time"        android:layout_alignParentRight="true"        android:layout_width="wrap_content"        android:layout_height="wrap_content" /></RelativeLayout>

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activity_main.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"    ><ListView            android:id="@+id/listview"            android:layout_width="match_parent"            android:layout_height="match_parent"            android:divider="#d8d8d8"            android:dividerHeight="1dp">        </ListView> </LinearLayout>

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MyAdapter.class:

package com.example.sm1n9.smingshop.Adapter;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.TextView;import com.example.sm1n9.smingshop.R;import java.util.HashMap;import java.util.List;/** * Created by user on 2016/6/23. */public class MyAdpterTest extends BaseAdapter {    private Context context;//上下文对象    private List<HashMap<String,Object>> list;//集合类 存放数据    private LayoutInflater inflater;//布局容器    public MyAdpterTest(Context context, List<HashMap<String, Object>> list) {//构造方法        this.context = context;        this.list = list;        inflater=LayoutInflater.from(context);    }    @Override    public int getCount() {        return list.size();    }    @Override    public Object getItem(int position) {        return list.get(position);    }    @Override    public long getItemId(int position) {        return position;    }    @Override    public View getView(int position, View convertView, ViewGroup parent) {    //ViewHolder通常出现在适配器里，为的是listview滚动的时候快速设置值，而不必每次都重新创建很多对象，从而提升性能            ViewHolder holder=null;        if (convertView == null) {                    holder=new ViewHolder();                    convertView=inflater.inflate(R.layout.item,null);                    holder.img= (ImageView) convertView.findViewById(R.id.user_face);                    holder.title= (TextView) convertView.findViewById(R.id.user_text);                    holder.info= (TextView) convertView.findViewById(R.id.user_message);                    holder.time= (TextView) convertView.findViewById(R.id.user_time);                    convertView.setTag(holder);        }        else{                   holder= (ViewHolder) convertView.getTag();        }                holder.img.setBackgroundResource((Integer) list.get(position).get("image"));                holder.title.setText((CharSequence) list.get(position).get("title"));                holder.info.setText((CharSequence) list.get(position).get("info"));                holder.time.setText((CharSequence) list.get(position).get("time"));        return convertView;    }    class  ViewHolder{        ImageView img;        TextView title;        TextView info;        TextView time;    }}

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ListView.class:

public class ListView extends Activity{     private ListView listView;     protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);        listView= (ListView)findViewById(R.id.listview);        List<HashMap<String,Object>> maps=new ArrayList<HashMap<String, Object>>();            HashMap<String,Object> map= new HashMap<String,Object>();            map.put("image", R.mipmap.h1);            map.put("title", "系统消息");            map.put("info", "OA办公体验站全新上线 哪里不会点哪里");            map.put("time", "刚刚");            maps.add(map);            map=new HashMap<String,Object>();            map.put("image", R.mipmap.h5);            map.put("title","abe");            map.put("info", "在干嘛？");            map.put("time","15:30");            map.put("ban",R.mipmap.icon_banned);            maps.add(map);            map=new HashMap<String,Object>();            map.put("image", R.mipmap.h2);            map.put("title", "Jack");            map.put("info", "o(^▽^)o");            map.put("time","12:30");            map.put("ban",R.mipmap.icon_banned);            maps.add(map);            map=new HashMap<String,Object>();            map.put("image", R.mipmap.h4);            map.put("title", "比卡丘");            map.put("info", "嗨");            map.put("time","昨天");            map.put("ban",R.mipmap.icon_banned);            maps.add(map);            listView.setAdapter(new MyAdpter(getActivity(), maps));    }}

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效果：

补充说明：

listView在开始绘制的时，系统首先调用getCount（）函数，根据他的返回值得到listView的长度，然后根据这个长度，调用getView（）逐一绘制每一行。如果你的getCount（）返回值是0的话，列表将不显示，## 标题 ##同样return 1，就只显示一行。