定制ListView的界面（使用自定义的列表项布局，一边显示水果图片，一边显示水果文字）以及ListView的点击事件

只能显示一段文本的ListView实在是太过单调，我们现在就来对ListView的界面进行定制，让它可以显示更加丰富的内容。

首先，我们需要准备好一组水果图片，分别对应上面提供的每一种水果，待会我们要让这些水果名称的旁边都有一个图样。

 

接着定义一个实体类，作为ListView适配器的适配类型。新建类Fruit，代码如下：

package com.example.administrator.activitydemo;

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;
    }
}

Fruit类中只有两个字段，name表示水果的名字，imageId表示水果对应图片的资源id。

然后需要为ListView的子项指定一个我们自定义的布局，在layout目录下新建fruit_item.xml，代码如下：

<?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">

    <ImageView
        android:id="@+id/iv_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/tv_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp" />
    
</LinearLayout>

在这个布局中，我们定义了一个ImageView用于显示水果的图片，又定义了一个TextView用于显示水果的名称，并让TextView在垂直方向上居中显示。

接下来需要创建一个自定义的适配器，这个适配器继承自ArrayAdapter，并将泛型指定为Fruit类。新建FruitAdapter，代码如下所示：

package com.example.administrator.activitydemo;

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;
    private List<Fruit> list;

    public FruitAdapter(Context context, int textViewResourceId, List<Fruit> list) {
        super(context, textViewResourceId, list);
        this.resourceId = textViewResourceId;
        this.list = list;
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit = list.get(position);//获取当前项的Fruit实例
        View view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
        ImageView iv_name = (ImageView) view.findViewById(R.id.iv_name);//初始化图片
        TextView tv_name = (TextView) view.findViewById(R.id.tv_name);//初始化文字
        iv_name.setImageResource(fruit.getImageId());//为ImageView设置图片
        tv_name.setText("" + fruit.getName());//为TextView设置文字
        return view;
    }
}

FruitAdapter重写了父类的一组构造函数，用于将上下文、ListView子项布局的id和数据都传递进来。另外又重写了getView()方法，这个方法在每个子项被滚动到屏幕内的时候会被调用。在getView()方法中，首先通过get()方法获得到当前项的Fruit实例，然后使用LayoutInflater来为这个子项加载我们传入的布局。

MainActivity.java代码：

package com.example.administrator.activitydemo;

import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private String[] data = {"Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango",
            "Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango"
    };
    private int[] res = {R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango,
            R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango};
    private List<Fruit> fruitList;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();//初始化UI控件
        initData();//初始化数据
    }


    private void initView() {
        listView = (ListView) findViewById(R.id.listView);
    }

    private void initData() {
        initFruits();//初始化水果数据
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);
        listView.setAdapter(adapter);
    }

    private void initFruits() {
        fruitList = new ArrayList<>();
        for (int i = 0; i < data.length; i++) {
            Fruit fruit = new Fruit(data[i], res[i]);
            fruitList.add(fruit);
        }
    }


}

运行程序，效果图：

是不是稍微好看了一点。

ListView的点击事件：

修改MainActivity.java中的代码：

package com.example.administrator.activitydemo;

import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private String[] data = {"Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango",
            "Apple", "Banana", "Orange", "Watermelon",
            "Pear", "Grape", "Pineapple", "Strawberry", "Cherry", "Mango"
    };
    private int[] res = {R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango,
            R.drawable.apple, R.drawable.banana, R.drawable.orange, R.drawable.watermelon,
            R.drawable.pear, R.drawable.grape, R.drawable.pineapple, R.drawable.strawberry, R.drawable.cherry, R.drawable.mango};
    private List<Fruit> fruitList;


    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();//初始化UI控件
        initData();//初始化数据
    }


    private void initView() {
        listView = (ListView) findViewById(R.id.listView);
    }

    private void initData() {
        initFruits();//初始化水果数据
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item, fruitList);
        listView.setAdapter(adapter);
    }

    private void initFruits() {
        fruitList = new ArrayList<>();
        for (int i = 0; i < data.length; i++) {
            Fruit fruit = new Fruit(data[i], res[i]);
            fruitList.add(fruit);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Fruit fruit = fruitList.get(position);
                Toast.makeText(MainActivity.this, "" + fruit.getName(), Toast.LENGTH_SHORT).show();
            }
        });
    }
}

效果图：