• 自定义ListView Android


    类似于iOS的UITableView

    定义一个实体类,作为ListView的适配器的适配类型。其中name为水果名称、imageId为水果的图片(图片资源可以随便弄几个占用)

    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;
    }

    }

    为ListView自定义布局

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    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_vertical"
    android:layout_marginLeft="10dp" />

    </LinearLayout>

    自定义适配器,继承自ArrayAdapter(最终提升了ListView的运行效率:convertView的重用、避免多次findViewById)

    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;

    }

    }

    修改MainActivity,设置ListView,选中某行弹出水果名称


    public class MainActivity extends AppCompatActivity {

    private List<Fruit> fruitList = new ArrayList<Fruit>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    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.list_view);
    listView.setAdapter(adapter);
    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();
    }
    });
    }

    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);
    }
    }

    }

    运行结果

    参考:《第一行代码》第二版

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  • 原文地址:https://www.cnblogs.com/huangzs/p/9006404.html
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