Listview及其优化

整个ListView展示包含1个javabean，1个adapter，一个listview，一个承载list的activity，以及listview子项的布局。
这里就贴一下代码吧

public class Fruit {
    private String name;
    private int id;
    public Fruit(String name,int id){
        this.name=name;
        this.id=id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }
}

这里定义了一个viewholder来复用控件，避免重复创建控件

public class FruitAdapter extends BaseAdapter {
    private List<Fruit>fruitList;
    private Context context;
    public FruitAdapter(Context context,List<Fruit> fruitList){
        this.fruitList=fruitList;
        this.context=context;
    }
    @Override
    public int getCount() {
        return fruitList.size();
    }

    @Override
    public Fruit getItem(int position) {
        return fruitList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Fruit fruit=getItem(position);
        View view;
        ViewHolder holder;
        if (convertView==null) {
            view = LayoutInflater.from(context).inflate(R.layout.fruititem, parent, false);
            holder=new ViewHolder();
            holder.fruitName=view.findViewById(R.id.fruit_name);
            holder.fruitImage=view.findViewById(R.id.fruit_image);
            view.setTag(holder);
        }else {
            view=convertView;
            holder= (ViewHolder) view.getTag();
        }
        holder.fruitImage.setImageResource(fruit.getId());
        holder.fruitName.setText(fruit.getName());
        return view;
    }
    class ViewHolder {
        private TextView fruitName;
        private ImageView fruitImage;
    }
}

public class ListviewActivity extends AppCompatActivity {
    List<Fruit>fruitList=new ArrayList<>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_listview);
        initFruits();
        ListView fruitLV= (ListView) findViewById(R.id.lvFruit);
        FruitAdapter adapter=new FruitAdapter(this,fruitList);
        fruitLV.setAdapter(adapter);
    }

    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);
        }
    }

}

<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"
        android:textSize="15sp"
        android:layout_marginLeft="10dp"/>

</LinearLayout>