1.ListView的简单使用
首先建立一个新的项目,在xml文件中添加ListView控件,如下所示:
<ListView android:id="@+id/list_view" android:layout_width="match_parent" android:layout_height="match_parent"></ListView>接下来修改MainActivity中的代码:
public class MainActivity extends AppCompatActivity { private String[] data={"Apple","Banana","Orange","Watermelon","Pear","Grape","Pineapple","Strawberry","Cherry","Mango","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.list_view); listView.setAdapter(adapter); }}将数据存储在数组中,借助ArrayAdapter适配器传递数据给ListView,最后调用setAdapter()方法,将适配器对象传递出去,关联建立完成。
2.定制ListView的界面
定义一个新的实体类,作为ListView适配器的适配类型。
public class Fruit { private String name;//水果名字 private int imageId;//水果对应图片id public Fruit(String name,int imageId){ this.name=name; this.imageId=imageId; } public int getImageId() { return imageId; } public java.lang.String getName() { return name; }}指定一个自定义布局,代码如下
<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_vertical" android:layout_marginLeft="10dp" /></LinearLayout>其中控件ImageView用来显示水果图片,TextView用来显示水果名称。接下来自定义一个适配器,继承自ArrayAdapter: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); View view= LayoutInflater.from(getContext()).inflate(resourceId,parent,false); 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; }}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。在重写的getView()方法中,首先通过getItem()方法得到当前的Fruit实例,然后使用LayoutInflater来为这个子项加载我们传入的数据。接下来对MainActivity进行修改:
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); } private void initFruits(){ for(int i=0;i<2;i++) { Fruit apple=new Fruit("Apple",R.drawable.fruit_1); fruitlist.add(apple); Fruit banana=new Fruit("banana",R.drawable.fruit_2); fruitlist.add(banana); Fruit orange=new Fruit("orange",R.drawable.fruit_1); fruitlist.add(orange); Fruit watermelon=new Fruit("watermelon",R.drawable.fruit_1); fruitlist.add(watermelon); Fruit pear=new Fruit("pear",R.drawable.fruit_2); fruitlist.add(pear); } }}
运行程序,效果如下:
3.ListView的点击事件
在MainActivity中添加如下代码(为ListView注册一个监听器),点击水果时可以显示该水果名:
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) { Fruit fruit=fruitlist.get(position); Toast.makeText(MainActivity.this,fruit.getName(),Toast.LENGTH_SHORT).show(); }});运行程序,效果如下:
原文地址:https://www.cnblogs.com/mqlblog/p/10566048.html
时间: 2024-11-10 18:10:35