自定义ListView的Adapter

快来打我* 2022-06-08 00:07 218阅读 0赞

**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) {
            switch (position) {
                case 0:
                    Log.d("Chunna.zheng","点击了第0项");
                    break;
                case 1:
                    Log.d("Chunna.zheng","点击了第1项");
                    break;
                case 2:
                    Log.d("Chunna.zheng","点击了第2项");
                    break;
                case 3:
                    Log.d("Chunna.zheng","点击了第3项");
                    break;
                case 4:
                    Log.d("Chunna.zheng","点击了第4项");
                    break;
            }
        }
    }