ListView(下)自定义适配器

Posted 2020-11-05 sunshine_96

 

 

 

（一）

1.效果图

2.activity_main.xml

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
 4     android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin"
 5     android:paddingLeft="@dimen/activity_horizontal_margin"
 6     android:paddingRight="@dimen/activity_horizontal_margin"
 7     android:paddingTop="@dimen/activity_vertical_margin"
 8     tools:context="com.example.app2.MainActivity">
 9 
10     <ListView
11         android:id="@+id/lv"
12         android:layout_width="wrap_content"
13         android:layout_height="wrap_content" />
14 </LinearLayout>

3.MianActivity.java

 1 package com.example.app2;
 2 
 3 import android.support.v7.app.AppCompatActivity;
 4 import android.os.Bundle;
 5 import android.widget.ListView;
 6 
 7 import java.text.SimpleDateFormat;
 8 import java.util.ArrayList;
 9 import java.util.List;
10 
11 public class MainActivity extends AppCompatActivity {
12     private ListView listView;
13     private List<Student>list;
14     private Student student;
15     private MyAdapter myAdapter;
16 
17     @Override
18     protected void onCreate(Bundle savedInstanceState) {
19         super.onCreate(savedInstanceState);
20         setContentView(R.layout.activity_main);
21         listView = (ListView) findViewById(R.id.lv);
22 
23         //新建数据源
24         list = new ArrayList<>();
25         for (int i=0;i<20;i++){
26             SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
27             String time = simpleDateFormat.format(System.currentTimeMillis());
28             student = new Student();
29             student.setStuName("张三"+i);
30             student.setStuNum("201503"+i);
31             student.setTime(time);
32             list.add(student);
33 
34 
35         }
36 
37         //新建适配器，适配器绑定数据
38         myAdapter = new MyAdapter(MainActivity.this,list);
39 
40         //视图加载适配器
41         listView.setAdapter(myAdapter);
42 
43 
44 
45 
46 
47     }
48 }

3.Studen.java(Alt+insert快捷键提示构造方法等)

 1 package com.example.app2;
 2 
 3 /**
 4  * Created by Administrator on 2018/5/16.
 5  */
 6 public class Student {
 7     private String stuName;
 8     private String stuNum;
 9     private String time;
10 
11     public String getStuNum() {
12         return stuNum;
13     }
14 
15     public void setStuNum(String stuNum) {
16         this.stuNum = stuNum;
17     }
18 
19     public String getStuName() {
20         return stuName;
21     }
22 
23     public void setStuName(String stuName) {
24         this.stuName = stuName;
25     }
26 
27     public String getTime() {
28         return time;
29     }
30 
31     public void setTime(String time) {
32         this.time = time;
33     }
34 }

4.自定义适配器MyAdapter.java

 1 package com.example.app2;
 2 
 3 import android.content.Context;
 4 import android.view.LayoutInflater;
 5 import android.view.TextureView;
 6 import android.view.View;
 7 import android.view.ViewGroup;
 8 import android.widget.BaseAdapter;
 9 import android.widget.ImageView;
10 import android.widget.TextView;
11 
12 import java.util.List;
13 
14 /**
15  * Created by Administrator on 2018/5/16.
16  */
17 public class MyAdapter extends BaseAdapter {
18     private Context context;
19     private List<Student> list;
20 
21     public MyAdapter(Context context, List<Student> list) {
22         this.context = context;
23         this.list = list;
24     }
25 
26     @Override
27     public int getCount() {
28         return list.size();
29     }
30 
31     @Override
32     public Object getItem(int position) {
33         return list.get(position);
34     }
35 
36     @Override
37     public long getItemId(int position) {
38         return position;
39     }
40 
41     @Override
42     public View getView(int position, View convertView, ViewGroup parent) {
43         convertView = LayoutInflater.from(context).inflate(R.layout.item,null);
44         //  获取控件
45         ImageView imageView = (ImageView)convertView.findViewById(R.id.iv);
46         TextView tv_name = (TextView)convertView.findViewById(R.id.tv_name);
47         TextView tv_num = (TextView)convertView.findViewById(R.id.tv_num);
48         TextView tv_time = (TextView)convertView.findViewById(R.id.tv_time);
49 
50         Student student = list.get(position);
51         imageView.setImageResource(R.mipmap.ic_launcher);
52         tv_name.setText(student.getStuName());
53         tv_num.setText(student.getStuNum());
54         tv_time.setText(student.getTime());
55 
56 
57         return convertView;
58     }
59 }

5.自定义item.xml布局

 1 <?xml version="1.0" encoding="utf-8"?>
 2 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:orientation="horizontal">
 6     <ImageView
 7         android:id="@+id/iv"
 8         android:background="@mipmap/ic_launcher"
 9         android:layout_width="100dp"
10         android:layout_height="100dp" />
11     <LinearLayout
12         android:layout_width="wrap_content"
13         android:layout_height="wrap_content"
14         android:orientation="vertical">
15         <TextView
16             android:layout_marginTop="10dp"
17             android:layout_marginLeft="20dp"
18             android:textSize="20dp"
19             android:id="@+id/tv_name"
20             android:layout_width="100dp"
21             android:layout_height="50dp" />
22         <TextView
23             android:layout_marginLeft="20dp"
24             android:textSize="20dp"
25             android:id="@+id/tv_num"
26             android:layout_width="100dp"
27             android:layout_height="30dp" />
28     </LinearLayout>
29     <TextView
30        android:id="@+id/tv_time"
31         android:layout_marginTop="30dp"
32         android:textSize="20dp"
33         android:layout_width="wrap_content"
34         android:layout_height="wrap_content" />
35 </LinearLayout>

 另：优化后的MyAdapter.java

 1 package com.example.app2;
 2 
 3 import android.content.Context;
 4 import android.view.LayoutInflater;
 5 import android.view.TextureView;
 6 import android.view.View;
 7 import android.view.ViewGroup;
 8 import android.widget.BaseAdapter;
 9 import android.widget.ImageView;
10 import android.widget.TextView;
11 
12 import java.util.List;
13 
14 /**
15  * Created by Administrator on 2018/5/16.
16  */
17 public class MyAdapter extends BaseAdapter {
18     private Context context;
19     private List<Student> list;
20 
21     public MyAdapter(Context context, List<Student> list) {
22         this.context = context;
23         this.list = list;
24     }
25 
26     @Override
27     public int getCount() {
28         return list.size();
29     }
30 
31     @Override
32     public Object getItem(int position) {
33         return list.get(position);
34     }
35 
36     @Override
37     public long getItemId(int position) {
38         return position;
39     }
40 
41     @Override
42     public View getView(int position, View convertView, ViewGroup parent) {
43        /* convertView = LayoutInflater.from(context).inflate(R.layout.item,null);
44         //  获取控件
45         ImageView imageView = (ImageView)convertView.findViewById(R.id.iv);
46         TextView tv_name = (TextView)convertView.findViewById(R.id.tv_name);
47         TextView tv_num = (TextView)convertView.findViewById(R.id.tv_num);
48         TextView tv_time = (TextView)convertView.findViewById(R.id.tv_time);
49 
50         Student student = list.get(position);
51         imageView.setImageResource(R.mipmap.ic_launcher);
52         tv_name.setText(student.getStuName());
53         tv_num.setText(student.getStuNum());
54         tv_time.setText(student.getTime());*/
55         ViewHolder viewHolder = null;
56         if(viewHolder==null){
57             viewHolder = new ViewHolder();
58             convertView = LayoutInflater.from(context).inflate(R.layout.item,null);
59             viewHolder.imageView = (ImageView)convertView.findViewById(R.id.iv);
60             viewHolder.tv_name = (TextView)convertView.findViewById(R.id.tv_name);
61             viewHolder.tv_num = (TextView)convertView.findViewById(R.id.tv_num);
62             viewHolder.tv_time = (TextView)convertView.findViewById(R.id.tv_time);
63             convertView.setTag(viewHolder);
64 
65         }else {
66             viewHolder=(ViewHolder)convertView.getTag();
67         }
68         Student student = list.get(position);
69         viewHolder.imageView.setImageResource(R.mipmap.ic_launcher);
70         viewHolder.tv_name.setText(student.getStuName());
71         viewHolder.tv_num.setText(student.getStuNum());
72         viewHolder.tv_time.setText(student.getTime()) ;
73         return convertView;
74     }
75     class ViewHolder{
76         ImageView imageView;
77         TextView tv_name ;
78         TextView tv_num ;
79         TextView tv_time ;
80     }
81 }