自定义ListView的Adapter

界面布局

只有一个listview

<?xml version="1.0" encoding="utf-8"?>
<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="@color/background"
    tools:context="com.sdlj.vehiclerepair.activity.SystemMessageActivity">
    <ListView
        android:id="@+id/lv_systemmsg"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:divider="@android:color/transparent"//设置分隔线颜色
        android:headerDividersEnabled="false"//设置上下边的分隔线不显示
        android:dividerHeight="2dp"//设置分隔线高度 
        />

</LinearLayout>

listview item布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="@dimen/systemmsg_listitem_height"
    android:background="@drawable/lvitem_systemmsg_shape">
    <ImageView
        android:id="@+id/iv_systemmsg_listitem"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"/>
    <TextView
        android:id="@+id/tv_systemmsg_listitem"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_vertical"
        android:textSize="16sp"
        android:textColor="#000000"/>

</LinearLayout>

最重要的Adapter类

继承BaseAdapter类，重写getCount()，getItem()，getItemId()，getView()方法

package com.sdlj.vehiclerepair.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.sdlj.vehiclerepair.activity.R;

import java.util.ArrayList;
import java.util.HashMap;


/**
 * Created by Chunna.zheng on 2017/9/8.
 */
public class SystemMsgListAdapter extends BaseAdapter{
    private ArrayList list ;
    private Context mContext;

	//避免了就是每次在getVIew的时候，都需要重新的findViewById，  
    // 重新找到控件，然后进行控件的赋值以及事件相应设置。这样其实在做重复的事情
    public class Holder{
        private ImageView image;
        private TextView title;

    }

    public SystemMsgListAdapter(Context context,ArrayList list){
        mContext = context;
        this.list = list;
    }

    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int i) {
        return list.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

	//重用了convertView，很大程度上的减少了内存的消耗。通过判断convertView是否为null，  
    // 是的话就需要产生一个视图出来，然后给这个视图数据，最后将这个视图返回给底层，呈献给用户。
    @Override
    public View getView(int position, View view, ViewGroup viewGroup) {
        Holder holder = null;
        LayoutInflater inflater = LayoutInflater.from(mContext);
        if(view == null){
            holder = new Holder();
            view = inflater.inflate(R.layout.item_systemmsg_list,null);
            holder.image = (ImageView)view.findViewById(R.id.iv_systemmsg_listitem);
            holder.title = (TextView)view.findViewById(R.id.tv_systemmsg_listitem);
            view.setTag(holder);
        }else{
            holder = (Holder)view.getTag();
        }
        holder.title.setText((Integer)((HashMap)list.get(position)).get("title"));
        holder.image.setBackgroundResource((Integer)((HashMap)list.get(position)).get("image"));
        return view;
    }
}

在Activity中使用Adapter

package com.sdlj.vehiclerepair.activity;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;

import com.sdlj.vehiclerepair.adapter.SystemMsgListAdapter;

import java.util.ArrayList;
import java.util.HashMap;

public class SystemMessageActivity extends AppCompatActivity implements AdapterView.OnItemClickListener{
    private ListView listView;
    private SystemMsgListAdapter adapter;
    private ArrayList arrayList;
    private HashMap map;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_system_message);
        initView();
    }

    private void initView() {
        listView = (ListView)findViewById(R.id.lv_systemmsg);
        arrayList = new ArrayList();
        map = new HashMap();
        map.put("image",R.mipmap.ic_systemmsg_msg);
        map.put("title",R.string.systemmsg_msg);
        arrayList.add(map);

        map = new HashMap();
        map.put("image",R.mipmap.ic_systemmsg_event);
        map.put("title",R.string.systemmsg_event);
        arrayList.add(map);

        map = new HashMap();
        map.put("image",R.mipmap.ic_systemmsg_rim);
        map.put("title",R.string.systemmsg_rim);
        arrayList.add(map);

        map = new HashMap();
        map.put("image",R.mipmap.ic_systemmsg_logistics);
        map.put("title",R.string.systemmsg_logistics);
        arrayList.add(map);

        map = new HashMap();
        map.put("image",R.mipmap.ic_systemmsg_friend);
        map.put("title",R.string.systemmsg_friend);
        arrayList.add(map);

        if(adapter==null){
            adapter = new SystemMsgListAdapter(this,arrayList);
        }else {
            //刷新适配器,不用每次都new
            adapter.notifyDataSetChanged();
        }
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(this);
    }
    
	//为列表设置点击事件
     @Override
    public void onItemClick(AdapterView<?> adapterView, View view, int position, long l) {
       Log.d("TAG","------position-----"+position);
       HashMap map = (HashMap) adapterView.getItemAtPosition(position);
       Log.d("TAG","-----------"+map.get("title"));
    }
}