Android ListView 定制界面(item)
layout_fruit_item.xml :
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<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>
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;
}
}
FruitAdapter.java:
public class FruitAdapter extends ArrayAdapter<Fruit> {
private int resourceId;
public FruitAdapter(Context context, int textViewResourceId, List<Fruit> objects) {
super(context, textViewResourceId, objects);
resourceId = textViewResourceId;
}
public View getView(int position, View convertView, ViewGroup parent) {
Fruit fruit = getItem(position);
View view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
ImageView fruitImage = view.findViewById(R.id.fruit_image);
TextView fruitName = view.findViewById(R.id.fruit_name);
fruitImage.setImageResource(fruit.getImageId());
fruitName.setText(fruit.getName());
return view;
}
}
MainActivity.java:
public class MainActivity extends AppCompatActivity {
private List<Fruit> fruitList = new ArrayList<>();
private void initFruits() {
for (int i = 0; i < 2; i++) {
Fruit apple = new Fruit("apple", R.mipmap.if_apple);
fruitList.add(apple);
Fruit grapes = new Fruit("grapes", R.mipmap.if_grapes);
fruitList.add(grapes);
Fruit orange = new Fruit("orange", R.mipmap.if_orange);
fruitList.add(orange);
Fruit mango = new Fruit("mango", R.mipmap.if_mango);
fruitList.add(mango);
Fruit pear = new Fruit("pear", R.mipmap.if_pear);
fruitList.add(pear);
Fruit pomegranate = new Fruit("pomegranate", R.mipmap.if_pomegranate);
fruitList.add(pomegranate);
Fruit pineapple = new Fruit("pineapple", R.mipmap.if_pineapple);
fruitList.add(pineapple);
Fruit lemon = new Fruit("lemon", R.mipmap.if_lemon);
fruitList.add(lemon);
Fruit strawberry = new Fruit("strawberry", R.mipmap.if_strawberry);
fruitList.add(strawberry);
Fruit watermelon = new Fruit("watermelon", R.mipmap.if_watermelon);
fruitList.add(watermelon);
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruits();
FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.layout_fruit_item, fruitList);
ListView listView = findViewById(R.id.list_view);
listView.setAdapter(adapter);
}
}
优化 FruitAdapter.java :
public class FruitAdapter extends ArrayAdapter<Fruit> {
private int resourceId;
public FruitAdapter(Context context, int textViewResourceId, List<Fruit> objects) {
super(context, textViewResourceId, objects);
resourceId = textViewResourceId;
}
public View getView(int position, View convertView, ViewGroup parent) {
Fruit fruit = getItem(position);
View view;
if (convertView == null) {
view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
} else {
view = convertView;
}
ImageView fruitImage = view.findViewById(R.id.fruit_image);
TextView fruitName = view.findViewById(R.id.fruit_name);
fruitImage.setImageResource(fruit.getImageId());
fruitName.setText(fruit.getName());
return view;
}
}
进一步优化 FruitAdapter.java :
public class FruitAdapter extends ArrayAdapter<Fruit> {
private int resourceId;
public FruitAdapter(Context context, int textViewResourceId, List<Fruit> objects) {
super(context, textViewResourceId, objects);
resourceId = textViewResourceId;
}
public View getView(int position, View convertView, 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 = view.findViewById(R.id.fruit_image);
viewHolder.fruitName = 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;
}
}
ListView 的点击事件
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initFruits();
FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.layout_fruit_item, fruitList);
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();
}
});
}