Android：简单demo之ListView

说明
更新日期	2019-01-21

效果图

MainActivity

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends Activity {

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

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.my_listview);

        initFruits();
        FruitAdapter adapter = new FruitAdapter(MainActivity.this, R.layout.fruit_item_layout, 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_LONG).show();
            }
        });

    }

    private void initFruits() {

        for(int i = 0; i < 3; i++) {
            Fruit apple = new Fruit("Apple", R.mipmap.ic_launcher);
            fruitList.add(apple);
        }

        for(int i = 0; i < 3; i++) {
            Fruit apple = new Fruit("Orange", R.mipmap.ic_launcher);
            fruitList.add(apple);
        }

        for(int i = 0; i < 3; i++) {
            Fruit apple = new Fruit("Pineapple", R.mipmap.ic_launcher);
            fruitList.add(apple);
        }

        for(int i = 0; i < 3; i++) {
            Fruit apple = new Fruit("Melon", R.mipmap.ic_launcher);
            fruitList.add(apple);
        }

        for(int i = 0; i < 3; i++) {
            Fruit apple = new Fruit("Peach", R.mipmap.ic_launcher);
            fruitList.add(apple);
        }

        for(int i = 0; i < 3; i++) {
            Fruit apple = new Fruit("Pear", R.mipmap.ic_launcher);
            fruitList.add(apple);
        }
    }
}

FruitAdapter

import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

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); // 获取当前项的Fruit实例
        View view;
        ViewHolder viewHolder = null;
        if (convertView == null) {
            view = LayoutInflater.from(getContext()).inflate(resourceID, null);
            viewHolder = new ViewHolder();
            viewHolder.fruitImage = view.findViewById(R.id.iv_fruit);
            viewHolder.fruitName = view.findViewById(R.id.tv_fruit);
            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;
    }
}

Fruit

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;
    }
}

fruit_item_layout.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="match_parent">

    <ImageView
        android:id="@+id/iv_fruit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="15dp"
        android:layout_marginTop="15dp"
        android:layout_marginBottom="15dp"
        android:src="@mipmap/ic_launcher"/>

    <TextView
        android:id="@+id/tv_fruit"
        android:text="默认文字"
        android:textSize="20sp"
        android:layout_gravity="center_vertical"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginLeft="10dp"/>

</LinearLayout>