ListView(下)自定义适配器

（一）

1.效果图

2.activity_main.xml

 <?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:paddingBottom="@dimen/activity_vertical_margin"
     android:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
     tools:context="com.example.app2.MainActivity">

     <ListView
         android:id="@+id/lv"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content" />
 </LinearLayout>

3.MianActivity.java

 package com.example.app2;

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

 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
 import java.util.List;

 public class MainActivity extends AppCompatActivity {
     private ListView listView;
     private List<Student>list;
     private Student student;
     private MyAdapter myAdapter;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         listView = (ListView) findViewById(R.id.lv);

         //新建数据源
         list = new ArrayList<>();
         for (int i=0;i<20;i++){
             SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
             String time = simpleDateFormat.format(System.currentTimeMillis());
             student = new Student();
             student.setStuName("张三"+i);
             student.setStuNum("201503"+i);
             student.setTime(time);
             list.add(student);

         }

         //新建适配器，适配器绑定数据
         myAdapter = new MyAdapter(MainActivity.this,list);

         //视图加载适配器
         listView.setAdapter(myAdapter);

     }
 }

3.Studen.java(Alt+insert快捷键提示构造方法等)

 package com.example.app2;

 /**
  * Created by Administrator on 2018/5/16.
  */
 public class Student {
     private String stuName;
     private String stuNum;
     private String time;

     public String getStuNum() {
         return stuNum;
     }

     public void setStuNum(String stuNum) {
         this.stuNum = stuNum;
     }

     public String getStuName() {
         return stuName;
     }

     public void setStuName(String stuName) {
         this.stuName = stuName;
     }

     public String getTime() {
         return time;
     }

     public void setTime(String time) {
         this.time = time;
     }
 }

4.自定义适配器MyAdapter.java

 package com.example.app2;

 import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.TextureView;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.BaseAdapter;
 import android.widget.ImageView;
 import android.widget.TextView;

 import java.util.List;

 /**
  * Created by Administrator on 2018/5/16.
  */
 public class MyAdapter extends BaseAdapter {
     private Context context;
     private List<Student> list;

     public MyAdapter(Context context, List<Student> list) {
         this.context = context;
         this.list = list;
     }

     @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) {
         convertView = LayoutInflater.from(context).inflate(R.layout.item,null);
         //  获取控件
         ImageView imageView = (ImageView)convertView.findViewById(R.id.iv);
         TextView tv_name = (TextView)convertView.findViewById(R.id.tv_name);
         TextView tv_num = (TextView)convertView.findViewById(R.id.tv_num);
         TextView tv_time = (TextView)convertView.findViewById(R.id.tv_time);

         Student student = list.get(position);
         imageView.setImageResource(R.mipmap.ic_launcher);
         tv_name.setText(student.getStuName());
         tv_num.setText(student.getStuNum());
         tv_time.setText(student.getTime());

         return convertView;
     }
 }

5.自定义item.xml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="horizontal">
     <ImageView
         android:id="@+id/iv"
         android:background="@mipmap/ic_launcher"
         android:layout_width="100dp"
         android:layout_height="100dp" />
     <LinearLayout
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:orientation="vertical">
         <TextView
             android:layout_marginTop="10dp"
             android:layout_marginLeft="20dp"
             android:textSize="20dp"
             android:id="@+id/tv_name"
             android:layout_width="100dp"
             android:layout_height="50dp" />
         <TextView
             android:layout_marginLeft="20dp"
             android:textSize="20dp"
             android:id="@+id/tv_num"
             android:layout_width="100dp"
             android:layout_height="30dp" />
     </LinearLayout>
     <TextView
        android:id="@+id/tv_time"
         android:layout_marginTop="30dp"
         android:textSize="20dp"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content" />
 </LinearLayout>

另：优化后的MyAdapter.java

 package com.example.app2;

 import android.content.Context;
 import android.view.LayoutInflater;
 import android.view.TextureView;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.BaseAdapter;
 import android.widget.ImageView;
 import android.widget.TextView;

 import java.util.List;

 /**
  * Created by Administrator on 2018/5/16.
  */
 public class MyAdapter extends BaseAdapter {
     private Context context;
     private List<Student> list;

     public MyAdapter(Context context, List<Student> list) {
         this.context = context;
         this.list = list;
     }

     @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) {
        /* convertView = LayoutInflater.from(context).inflate(R.layout.item,null);
         //  获取控件
         ImageView imageView = (ImageView)convertView.findViewById(R.id.iv);
         TextView tv_name = (TextView)convertView.findViewById(R.id.tv_name);
         TextView tv_num = (TextView)convertView.findViewById(R.id.tv_num);
         TextView tv_time = (TextView)convertView.findViewById(R.id.tv_time);

         Student student = list.get(position);
         imageView.setImageResource(R.mipmap.ic_launcher);
         tv_name.setText(student.getStuName());
         tv_num.setText(student.getStuNum());
         tv_time.setText(student.getTime());*/
         ViewHolder viewHolder = null;
         if(viewHolder==null){
             viewHolder = new ViewHolder();
             convertView = LayoutInflater.from(context).inflate(R.layout.item,null);
             viewHolder.imageView = (ImageView)convertView.findViewById(R.id.iv);
             viewHolder.tv_name = (TextView)convertView.findViewById(R.id.tv_name);
             viewHolder.tv_num = (TextView)convertView.findViewById(R.id.tv_num);
             viewHolder.tv_time = (TextView)convertView.findViewById(R.id.tv_time);
             convertView.setTag(viewHolder);

         }else {
             viewHolder=(ViewHolder)convertView.getTag();
         }
         Student student = list.get(position);
         viewHolder.imageView.setImageResource(R.mipmap.ic_launcher);
         viewHolder.tv_name.setText(student.getStuName());
         viewHolder.tv_num.setText(student.getStuNum());
         viewHolder.tv_time.setText(student.getTime()) ;
         return convertView;
     }
     class ViewHolder{
         ImageView imageView;
         TextView tv_name ;
         TextView tv_num ;
         TextView tv_time ;
     }
 }