实验 ListView

最新推荐文章于 2020-11-30 09:51:58 发布

chenshengxiang

最新推荐文章于 2020-11-30 09:51:58 发布

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本文链接：https://blog.youkuaiyun.com/chenshengxiang/article/details/53046901

这篇博客详细介绍了如何在Android中创建并使用ListView，包括MainActivity.java的实现，Fruit.java的数据模型，FruitAdapter.java的适配器代码，以及activity.xml和fruit_item.xml的布局文件设计。通过这些步骤，读者可以理解并实现一个完整的ListView展示应用。

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app运行图：

mainactivity.java的代码：

package cn.example.cx_3_5_listview;

import java.util.ArrayList;
import java.util.List;

import android.app.Activity;
import android.os.Bundle;
import android.widget.ListView;

public class MainActivity extends Activity
{
	private List<Fruit> fruitList = new ArrayList<Fruit>();

	/*
	 * private String[] data = { "Apple", "Banana", "Orange", "Watermelon",
	 * "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango" };
	 */

	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		/*
		 * ArrayAdapter<String> adapter = new ArrayAdapter<String>(
		 * MainActivity.this, android.R.layout.simple_list_item_1, data);
		 * ListView listView = (ListView) findViewById(R.id.lv1);
		 * listView.setAdapter(adapter);
		 */

		initFruits(); // 初始化水果数据
		FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);
		ListView listView = (ListView) findViewById(R.id.lv1);
		listView.setAdapter(adapter);
	}

	private void initFruits()
	{
		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 apple1 = new Fruit("Apple", R.drawable.apple_pic);
		fruitList.add(apple);
		Fruit banana1 = new Fruit("Banana", R.drawable.banana_pic);
		fruitList.add(banana);
		Fruit orange1 = new Fruit("Orange", R.drawable.orange_pic);
		fruitList.add(orange);
		Fruit watermelon1 = new Fruit("Watermelon", R.drawable.watermelon_pic);
		fruitList.add(watermelon);

	}
}

新建 Fruit.java的全部代码：

package cn.example.cx_3_5_listview;

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;
	}

}

新建FruitAdapter.java :

package cn.example.cx_3_5_listview;

import java.util.List;

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;

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, null);
			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
		}

		ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
		TextView fruitName = (TextView) view.findViewById(R.id.fruit_name);
		fruitImage.setImageResource(fruit.getImageId());
		fruitName.setText(fruit.getName());
		return view;
	}

	class ViewHolder
	{

		ImageView fruitImage;

		TextView fruitName;

	}

}

activity.xml的全部代码：

<RelativeLayout 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" >

    <ListView
        android:id="@+id/lv1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
 >
    </ListView>

</RelativeLayout>

新建fruit_item.xml的全部代码：

<?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">
    <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"
        android:layout_gravity="center"
        android:layout_marginLeft="10dip" />
    
    

</LinearLayout>