移动技术开发：ListView水果列表

1 实验名称

ListView水果列表

2 实验目的

掌握自定义ListView控件的实现方法

3 实验源代码

布局文件代码：

activity_main.xml:

java 复制代码

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
    tools:context=".MainActivity">
    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/list_view"/>
</LinearLayout>

fruit_item.xml:

java 复制代码

<?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="wrap_content">
    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />
</LinearLayout>

Java代码 :

MainActivaty.java:

java 复制代码

package com.example.listviewtest;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    private ListView list_view = null;
    //初始化列表中的数据
    private String []dates = {"Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango",
            "Apple", "Banana", "Orange", "Watermelon", "Pear", "Grape",
            "Pineapple", "Strawberry", "Cherry", "Mango"};

    //创建一个水果列表数据源
    private List<Fruit> fruitList = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //创建一个列表适配器
        //ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(MainActivity.this,
        //        android.R.layout.simple_list_item_1,dates);
        //list_view.findViewById(R.id.list_view);
        //list_view.setAdapter(arrayAdapter);
        initFruits();//将水果列表数据源中的数据生成
        //创建水果适配器对象
        FruitAdapter fruitAdapter = new FruitAdapter(MainActivity.this,
                R.layout.fruit_item,//列表子项的布局文件
                fruitList);//列表数据源
        //创建列表
        ListView listView = findViewById(R.id.list_view);
        listView.setAdapter(fruitAdapter);
    }

    private void initFruits(){
        for (int i = 0; i < 2; i++) {
            Fruit apple = new Fruit("Apple", R.drawable.apple_pic);
            fruitList.add(apple);
            Fruit banana = new Fruit("Banana", R.drawable.banana_pic);
            fruitList.add(banana);
            Fruit orange = new Fruit("Orange", R.drawable.orange_pic);
            fruitList.add(orange);
            Fruit watermelon = new Fruit("Watermelon", R.drawable.watermelon_pic);
            fruitList.add(watermelon);
            Fruit pear = new Fruit("Pear", R.drawable.pear_pic);
            fruitList.add(pear);
            Fruit grape = new Fruit("Grape", R.drawable.grape_pic);
            fruitList.add(grape);
            Fruit pineapple = new Fruit("Pineapple", R.drawable.pineapple_pic);
            fruitList.add(pineapple);
            Fruit strawberry = new Fruit("Strawberry", R.drawable.strawberry_pic);
            fruitList.add(strawberry);
            Fruit cherry = new Fruit("Cherry", R.drawable.cherry_pic);
            fruitList.add(cherry);
            Fruit mango = new Fruit("Mango", R.drawable.mango_pic);
            fruitList.add(mango);
        }

    }

}

Fruit.java:

java 复制代码

package com.example.listviewtest;
public class Fruit {
    private String name;
    private int imageId;
    public Fruit(String name, int imageId) {
        this.name = name;
        this.imageId = imageId;
    }

    public String getName() {
        return name;
    }

    public int getImageId() {
        return imageId;
    }
}

FruitAdapter.java:

java 复制代码

package com.example.listviewtest;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;
public class FruitAdapter extends ArrayAdapter<Fruit> {
    private int resourceId;
    public FruitAdapter(Context context, int textViewResourceId, List<Fruit> objects) {
        super(context, textViewResourceId, objects);
        resourceId = textViewResourceId;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = getItem(position); // 获取当前项的Fruit实例
        View view;
        ViewHolder viewHolder;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = (ImageView) view.findViewById (R.id.fruit_image);
            viewHolder.fruitName = (TextView) view.findViewById (R.id.fruit_name);
            view.setTag(viewHolder); // 将ViewHolder存储在View中
        } else {
            view = convertView;
            viewHolder = (ViewHolder) view.getTag(); // 重新获取ViewHolder
        }
        viewHolder.fruitImage.setImageResource(fruit.getImageId());
        viewHolder.fruitName.setText(fruit.getName());
        return view;
    }

    class ViewHolder {
        ImageView fruitImage;
        TextView fruitName;
    }

}

4 实验运行结果图

5 总结

先写好布局文件，这个实验一共有量个布局文件。实验在activity_main.xml和fruit_item.xml布局文件中就是列表所罗列的水果；在activity_main.xml布局文件中，设置了一个列表；而fruit_item.xml布局文件中在列表每一行中插入图片和文本框。

在写Java代码过程中，初始化列表中的数据，创建一个水果列表数据源和一个列表适配器，将水果列表数据源中的数据生成；创建水果适配器对象，创建列表获取当前项的水果实例。