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
<?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
<?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
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
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
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。