ListView的实现步骤

1、在mainactivity_layout中使用LinearLayout布局，加入ListView控件

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

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

</LinearLayout>

2、创建fruit_item的layout，完成显示名称，图片等信息的布局

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <!--显示水果的图片-->
    <ImageView
        android:id="@+id/fruit_image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    <!--显示水果的名称-->
    <TextView
        android:id="@+id/fruit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginLeft="10dp"/>

</LinearLayout>

3、创建Fruit.java实体类，定义有参构造器和getxxx()方法

public class Fruit {
    private String name;//水果的名字
    private int imgId;//水果对应图片资源的ID

    public Fruit(String name, int imgId) {
        this.name = name;
        this.imgId = imgId;
    }

    public String getName() {
        return name;
    }

    public int getImgId() {
        return imgId;
    }
}

4、创建自定义的适配器继承自ArrayAdapter<Fruit>

        4-1 定义构造函数

  private int resourceId;
/*  private ImageView fruitImg;
  private TextView fruitName;*/

  public FruitAdapter(@NonNull Context context, int textViewResourceId, @NonNull List<Fruit> objects) {
      super(context, textViewResourceId, objects);
       resourceId = textViewResourceId;
  }

        4-2 重写getView(int position, @Nullable View convertView, @NonNull ViewGroup parent)方法

@NonNull
@Override
public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
    //获取当前项的Fruit实例
    Fruit fruit = getItem(position);
    /*View view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);*/
    //利用convertView提升运行效率
  /*  View view;
    if (convertView == null){
        //convertView缓存中没有布局，加载布局
        view = LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
    }else{
        //convertView缓存有加载完成的布局，直接调用
        view = convertView;
    }*/

  //同时优化convertView和调用控件
    View view;
    Viewholder viewholder;
    if (convertView == null){
        //convert缓存中没有布局，加载布局
        view = LayoutInflater.from(getContext()).inflate(resourceId,parent,false);
        viewholder = new Viewholder();
        viewholder.fruitImg = view.findViewById(R.id.fruit_image);
        viewholder.fruitName = view.findViewById(R.id.fruit_name);
        view.setTag(viewholder);//讲viewholder存储在View中
    }else {
        view = convertView;
        viewholder = (Viewholder) view.getTag();//重新获取viewholder
    }
    //设置水果的图片
    /*fruitImg = view.findViewById(R.id.fruit_image);//多次调用控件可优化*/
    viewholder.fruitImg.setImageResource(fruit.getImgId());
    //设置水果名
    /*fruitName = view.findViewById(R.id.fruit_name);*/
    viewholder.fruitName.setText(fruit.getName());
    return view;
}
class Viewholder{
    ImageView fruitImg;
    TextView fruitName;
}

5、在main_activity_layout中完成以下步骤：

        1、初始化数据

        2、调用自定义的适配器创建适配器对象

        3、传入数据，进行展示

public class MainActivity extends AppCompatActivity {

    //初始化数据
   /* private String[] data = {"apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","cherry","Mongo",
            "apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","cherry","Mongo"};
*/
    private List<Fruit> fruitList = new ArrayList<>();
    private ListView mLv1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //无图片时
        /*//创建适配器对象
        ArrayAdapter<String> adapter = new ArrayAdapter<>(MainActivity.this,android.R.layout.simple_list_item_1,data);
        mLv1 = findViewById(R.id.ListView);
        //传入数据
        mLv1.setAdapter(adapter);*/
        //有图片时
        //初始化水果数据
        initFruits();
        //调用自定义的水果适配器创建适配器对象
        FruitAdapter fruitAdapter = new FruitAdapter(MainActivity.this,R.layout.fruit_item,fruitList);
        //传入数据
        mLv1 = findViewById(R.id.ListView);
        mLv1.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("Bnana", R.drawable.banana_pic);
            fruitList.add(banana);
            Fruit orange = new Fruit("Orange", R.drawable.apple_pic);
            fruitList.add(orange);
            Fruit watermelon = new Fruit("Watermelon", R.drawable.apple_pic);
            fruitList.add(watermelon);
            Fruit pear = new Fruit("Pear", R.drawable.apple_pic);
            fruitList.add(pear);
            Fruit grape = new Fruit("Grape", R.drawable.apple_pic);
            fruitList.add(grape);
            Fruit pineapple = new Fruit("Pineapple", R.drawable.apple_pic);
            fruitList.add(pineapple);
            Fruit strawberry = new Fruit("Strawberry", R.drawable.apple_pic);
            fruitList.add(strawberry);
            Fruit cherry = new Fruit("Cherry", R.drawable.apple_pic);
            fruitList.add(cherry);
            Fruit mongo = new Fruit("Mongo", R.drawable.apple_pic);
            fruitList.add(mongo);

        }
    }
}