标签:class length vat 使用 width div override near string
ListView是Android最常用的控件之一,允许用户通过手指上下滑动的方式将屏幕外的数据滚动到屏幕内。ListView通过Adapter加载数据到屏幕上。
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <ListView android:id="@+id/list_view" android:layout_width="match_parent" android:layout_height="match_parent"></ListView> </LinearLayout>
MainActivity.java
public class MainActivity extends AppCompatActivity { private List<Fruit> fruitList = new ArrayList<>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initFruits(); 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 watermelon = new Fruit("Watermelon",R.drawable.watermelon_pic); 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 strawberry = new Fruit("Strawberry",R.drawable.strawberry_pic); fruitList.add(strawberry); Fruit mango = new Fruit("Mango",R.drawable.mango_pic); fruitList.add(mango); } } }
FruitAdapter.java 在getView方法中进行了ListView运行效率优化
public class FruitAdapter extends ArrayAdapter<Fruit> { private int resourceId; public FruitAdapter(Context context, int textViewResourceId, List<Fruit> objects) { super(context, textViewResourceId,objects); resourceId = textViewResourceId; } @NonNull @Override public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) { Fruit fruit = getItem(position); 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); } else { view = convertView; viewHolder = (ViewHolder) view.getTag(); } viewHolder.fruitImage.setImageResource(fruit.getImageId()); viewHolder.fruitName.setText(fruit.getName()); return view; } class ViewHolder { ImageView fruitImage; TextView fruitName; } }
Fruit.java
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; } }
标签:class length vat 使用 width div override near string
原文地址:https://www.cnblogs.com/kyun/p/10310415.html