andorid studio 之初识ListView

客官°小女子只卖身不卖艺 2022-04-18 06:49 207阅读 0赞

#   这个是我自学ListVew，在看视频过程中做的小案例 #

# **一：理解ListView** #

ListView是一种用来显示多个可滑动顼列表(item)的viewGruop.

需要使用Adapter将集合数据 和每一个Item所对应的布局动态适配到ListView中显示。

显示列表：ListView.setAdapter(adapter);

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzQxODYxNzUx_size_16_color_FFFFFF_t_70][]

# **二.Adapter层次图** #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzQxODYxNzUx_size_16_color_FFFFFF_t_70 1][]

现在我们从最简单的的列表开始讲解：

### **1、ArrayAdapter** ###

## **       1.1-效果图** ##

**       ![20181109221112392.gif][]**

##       1.2、涉及到的知识点 ##

setAdapter 显示列表

##       1.3、创建一个项目ListViewDemo01 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzQxODYxNzUx_size_16_color_FFFFFF_t_70 2][]

1.4、布局文件activity_main.xml中的代码

<?xml version="1.0" encoding="utf-8"?>
    <ListView xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/lv_main"
        tools:context=".MainActivity">
    </ListView>

** 1.5 创建一个Item.xml文件**

**       **

<?xml version="1.0" encoding="utf-8"?>
    <TextView
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:textSize="20dp"
        android:gravity="center_vertical"
        android:layout_height="50dp">
    </TextView>

# #

##   1.6、 设置MainActivity.xml中的代码 ##

![20181109221956740.png][]

![20181109221944638.png][]

package com.example.a20473.listviewdemo01;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.widget.ArrayAdapter;
    import android.widget.ListView;
    
    public class MainActivity extends AppCompatActivity {
    
        private ListView lv_main;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
    
            lv_main = findViewById(R.id.lv_main);
    
            //准备集合数据
            String [] data = {"A","B","C","D","E","F","H","I","J","K","L","M","N"};
            //准备ArrayAdapter对象
            ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.item,data);
            //设置显示Adapter列表
            lv_main.setAdapter(adapter);
    
    
        }
    }

简单的ArrayAdapter列表就制作完成了

# **2、SimpleAdapter** #

### **       2.1  SimpleAdater参数的理解** ###

![20181110102031166.png][]**  **

**      第一个参数 context:上下文对象。**

**      第二个参数 data:需要显示的数据集合。**

**      第三个参数 resource:Item布局标识。**

**      第四个参数 from:map对象中的key数组，用于得到相应的value。**

**      第五个参数 to:item布局文件中的子view的id的数组。**

**      效果图：**

**        ![20181110103742795.gif][]**

### **      2.2 创建项目**SimpleAdapter  ，并准备好图片素材 ###

###       2.3  设置主布局文件activity\_main.xml ###

2.4  新建布局文件item.xml    代码如下

![20181110103341756.png][]

<?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="wrap_content"
        android:orientation="horizontal"
        >
        <ImageView
            android:id="@+id/iv_item_icon"
            android:layout_width="70dp"
            android:layout_height="70dp"
            android:src="@mipmap/f1"/>
         <LinearLayout
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:gravity="center_vertical"
             android:orientation="vertical"
             android:layout_marginLeft="10dp"
             >
             <TextView
                 android:id="@+id/tv_item_name"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="name"/>
    
             <TextView
                 android:id="@+id/tv_item_content"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="content"/>
    
         </LinearLayout>
    
    
    
    </LinearLayout>

2.4 设置主窗口的MainActivity.java

package com.example.a20473.simpleadapter;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.widget.ListView;
    import android.widget.SimpleAdapter;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    public class MainActivity extends AppCompatActivity {
        private ListView lv_main;
    
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            lv_main = findViewById(R.id.lv_main);
    
            //准备好集合数据
            List<Map<String,Object>> data = new ArrayList<Map<String,Object>>();
            Map<String ,Object> map = new HashMap<String ,Object>();
    
            map.put("icom",R.mipmap.f1);
            map.put("name","name--1");
            map.put("content","content--1");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f2);
            map.put("name","name--2");
            map.put("content","content--2");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f3);
            map.put("name","name--3");
            map.put("content","content--3");
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f4);
            map.put("name","name--4");
            map.put("content","content--4");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f5);
            map.put("name","name--5");
            map.put("content","content--5");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f6);
            map.put("name","name--6");
            map.put("content","content--6");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f7);
            map.put("name","name--7");
            map.put("content","content--7");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f8);
            map.put("name","name--8");
            map.put("content","content--8");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f9);
            map.put("name","name--9");
            map.put("content","content--9");
            data.add(map);
    
            map = new HashMap<String ,Object>();
            map.put("icom",R.mipmap.f10);
            map.put("name","name--10");
            map.put("content","content--10");
    
            data.add(map);
    
            //MAP对象中的KEY数组，用于得到value
            String[] from = {"icom","name","content"};
            //item布局文件的子view的id数组
            int[] to={R.id.iv_item_icon,R.id.tv_item_name,R.id.tv_item_content};
    
    
            //准备SimpleAdapter
            SimpleAdapter adapter = new SimpleAdapter(this,data,R.layout.item,from,to);
    
            //显示列表
            lv_main.setAdapter(adapter);
        }
    }

# 3.BaseAdapter #

3.1BaseAdapter

字面意思就是 最基础的Adapter，也就是说，它可以做所有的事情。所以为什么说最实用最常用，原因就在于它的全能性，不 会像 ArrayAdapter等的封装好的类有那么多局限性，但是这样的话，使用起来自然会更加麻烦一点。他是一个抽象类，需要创 建一个类来实现他，

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzQxODYxNzUx_size_16_color_FFFFFF_t_70 3][]

我们知道继承BaseAdapter需要重新四个方法：getCount、getItem、getItemId、getView。其中前三个都比较简单，而               getView稍微比较复杂。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzQxODYxNzUx_size_16_color_FFFFFF_t_70 4][]

3.2效果图（其实和上面的SimpleAdapter一样，只是用的方法不一样）

![20181110113525694.gif][]

3.3创建一个项目BaseAdapter  并将准备好的素材放复制进去

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2JhaWR1XzQxODYxNzUx_size_16_color_FFFFFF_t_70 5][]

3.4 先设置主布局文件的activity.xml中的文件

3.5 创建一个布局文件item.xml

3.6 创建一个类ShopInfo  (在下面的 我们自定义List集合中要用)

![20181110113954634.png][]

package com.example.a20473.baseadapter;
    
    
    //这个是每一行Item的数据信息封装类
    public class ShopInfo {
        private int icon;
        private String name;
        private String content;
    
        public ShopInfo() {
            super();
        }
        public ShopInfo(int icon, String name, String content) {
            super();
            this.icon = icon;
            this.name = name;
            this.content = content;
        }
    
        public int getIcon() {
            return icon;
        }
    
        public void setIcon(int icon) {
            this.icon = icon;
        }
    
        public String getName() {
            return name;
        }
        public void setName(String name) {
            this.name = name;
        }
    
        public String getContent() {
            return content;
        }
    
        public void setContent(String content) {
            this.content = content;
        }
    
        @Override
        public String toString() {
            return "ShopInfo{" +
                    "icon=" + icon +
                    ", name='" + name + '\'' +
                    ", content='" + content + '\'' +
                    '}';
        }
    }

## 3.7 设置MainAcitity.java文件 ##

package com.example.a20473.baseadapter;
    
    import android.app.Activity;
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.BaseAdapter;
    import android.widget.ImageView;
    import android.widget.ListView;
    import android.widget.SimpleAdapter;
    import android.widget.TextView;
    
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.List;
    import java.util.Map;
    
    public class MainActivity extends AppCompatActivity {
        private ListView lv_main;
        List<ShopInfo> data;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            lv_main = findViewById(R.id.lv_main);
            //准备好集合数据  自定义集合
            data = new ArrayList<ShopInfo>();
            data.add(new ShopInfo(R.mipmap.f1,"name----1","cotent----1"));
            data.add(new ShopInfo(R.mipmap.f2,"name----2","cotent----2"));
            data.add(new ShopInfo(R.mipmap.f3,"name----3","cotent----3"));
            data.add(new ShopInfo(R.mipmap.f4,"name----4","cotent----4"));
            data.add(new ShopInfo(R.mipmap.f5,"name----5","cotent----5"));
            data.add(new ShopInfo(R.mipmap.f6,"name----6","cotent----6"));
            data.add(new ShopInfo(R.mipmap.f7,"name----7","cotent----7"));
            data.add(new ShopInfo(R.mipmap.f8,"name----8","cotent----8"));
            data.add(new ShopInfo(R.mipmap.f9,"name----9","cotent----9"));
            data.add(new ShopInfo(R.mipmap.f10,"name----10","cotent----10"));
            //准备BaseAdapter对象   它是抽象的 所以我们 要实例化继承它的类
            MyAdapter adapter = new MyAdapter();
            //显示列表
            lv_main.setAdapter(adapter);
        }
            class  MyAdapter extends  BaseAdapter{
                //返回集合数据中的数量
                @Override
                public int getCount() {
                    return  data.size();
                }
                //返回指定下标对应的数据对象
                @Override
                public Object getItem(int position) {
                    return data.get(position);
                }
    
                @Override
                public long getItemId(int position) {
                    return 0;
                }
                //返回指定下标所对应的item的View 对象
                //position:下标
                //convertView：  可复用的Item缓存对象   前n+1个为null
                // parent  : ListView对象
                @Override
                public View getView(int position, View convertView, ViewGroup parent) {
    
                    if(convertView == null){
                        // 加载Item视图对象  得到View对象
                        convertView= View.inflate(MainActivity.this,R.layout.item,null);
                    }
                   //根据Position设置对应的数据
                        //得到当前行的数据对象
                    ShopInfo shopInfo = data.get(position);
                         //得到子View对象
                    ImageView imageView = convertView.findViewById(R.id.iv_item_icon);
                    TextView NameTV   =convertView.findViewById(R.id.tv_item_name);
                    TextView  ContentTv = convertView.findViewById(R.id.tv_item_content);
                          //设置数据
                    imageView.setImageResource(shopInfo.getIcon());
                    NameTV.setText(shopInfo.getName());
                    ContentTv.setText(shopInfo.getContent());
    
                    return convertView;
    
                }
            }
    
    }

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[20181109221112392.gif]: /images/20220418/4b48e4018a48451abe1cc127fb2d7abf.png
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[20181109221956740.png]: /images/20220418/72914c9f6e03495f9f03d57affe29780.png
[20181109221944638.png]: /images/20220418/2ea94b0f9a4f4df1b548250ad1cdd6ee.png
[20181110102031166.png]: /images/20220418/a086caa645b74b9d9362cffb06e048a1.png
[20181110103742795.gif]: /images/20220418/314be00be0ae4328a4e7aa567f53fe42.png
[20181110103341756.png]: /images/20220418/b8a0bb98a42a4445a62074c9893bd9bf.png
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[20181110113525694.gif]: /images/20220418/85cc46ea48ae4a48aa57be070eba25e9.png
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[20181110113954634.png]: /images/20220418/92c5b572663042b298338b988388ca9d.png