Android ListView自定义适配器adapter中ConvertView优化及CheckBox处理

本篇博客（实例代码）讲ListView自定义Adapter的用法，重点为使用convertView优化程序，并对使用CheckBox产生的问题予以解决

MyListViewActivity

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

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

public class MyListViewActivity extends AppCompatActivity implements View.OnClickListener {
    List<Fruit> fruitList = new ArrayList<>();
    private MyFruitAdapter adapter;
    private Button selectAll;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mylistview);
        prepareFruits();
        selectAll = findViewById(R.id.btn_selectAll);
        selectAll.setOnClickListener(this);
        Button deleteSelected = findViewById(R.id.btn_deleteSelected);
        deleteSelected.setOnClickListener(this);

        adapter = new MyFruitAdapter(MyListViewActivity.this, R.layout.myfruititem, fruitList);
        ListView listView = this.findViewById(R.id.lv_fruits);
        listView.setAdapter(adapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Toast.makeText(MyListViewActivity.this, adapter.getItem(position).getName(), Toast.LENGTH_LONG).show();
            }
        });
    }

    public void onClick(View view) {
        int id = view.getId();
        switch (id) {
            case R.id.btn_selectAll:
                Button btn = (Button) view;
                if (btn.getText().equals("SelectAll")) {
                    btn.setText("SelectNone");
                    adapter.selectAll();
                } else {
                    btn.setText("SelectAll");
                    adapter.selectNone();
                }
                break;
            case R.id.btn_deleteSelected:
                adapter.deleteSelected();
                break;
            default:
                break;
        }
    }

    public void prepareFruits() {
        for (int i = 0; i < 20; i++) {
            fruitList.add(new Fruit("Apple" + String.valueOf(i), R.drawable.apple_pic));
            fruitList.add(new Fruit("Banana" + String.valueOf(i), R.drawable.banana_pic));
            fruitList.add(new Fruit("Orange" + String.valueOf(i), R.drawable.orange_pic));
            fruitList.add(new Fruit("Watermelon" + String.valueOf(i), R.drawable.watermelon_pic));
            fruitList.add(new Fruit("Pear" + String.valueOf(i), R.drawable.pear_pic));
            fruitList.add(new Fruit("Grape" + String.valueOf(i), R.drawable.grape_pic));
            fruitList.add(new Fruit("Pineapple" + String.valueOf(i), R.drawable.pineapple_pic));
            fruitList.add(new Fruit("Strawberry" + String.valueOf(i), R.drawable.strawberry_pic));
            fruitList.add(new Fruit("Cherry" + String.valueOf(i), R.drawable.cherry_pic));
            fruitList.add(new Fruit("Mango" + String.valueOf(i), R.drawable.mango_pic));
        }
    }
}

MyFruitAdapter

import android.content.Context;
import android.graphics.Color;
import android.support.annotation.NonNull;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class MyFruitAdapter extends ArrayAdapter<Fruit> {

    private Context context;
    private int resource;
    private FruitManager fruitManager;
    private Map<String, Boolean> map = new HashMap();

    MyFruitAdapter(Context context, int resource, List<Fruit> objects) {
        super(context, resource, objects);
        this.context = context;
        this.resource = resource;
        fruitManager = new FruitManager(objects);
        for (int i = 0; i < objects.size(); i++) {
            map.put(objects.get(i).getName(), false);
        }
    }

    private class ViewHolder {
        private LinearLayout ll;
        private ImageView iv;
        private TextView tv;
        private CheckBox cb;
        private Button btn;
    }

    @NonNull
    @Override
    public View getView(int position, View convertView, @NonNull ViewGroup parent) {
        ViewHolder vh; 
        if (convertView == null) {
            vh = new ViewHolder();
            convertView = LayoutInflater.from(getContext()).inflate(resource, parent, false);

            vh.iv = convertView.findViewById(R.id.iv_fruitImage);
            vh.tv = convertView.findViewById(R.id.tv_fruitName);

            CheckBox checkBox = convertView.findViewById(R.id.cb_selectItem);
            checkBox.setTag(position);
            checkBox.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    CheckBox cb = (CheckBox) v;
                    if (cb.isChecked()) {
                        map.put(getItem((int) cb.getTag()).getName(), true);
                    } else {
                        map.put(getItem((int) cb.getTag()).getName(), false);
                    }
                }
            });
            vh.cb = checkBox;

            Button button = convertView.findViewById(R.id.btn_delete);
            button.setTag(position);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    //Toast.makeText(context, fruit.getName(), Toast.LENGTH_LONG).show();
                    Button btn = (Button) v;
                    map.remove(getItem((int) btn.getTag()).getName());
                    fruitManager.deleteFruit(getItem((int) btn.getTag()).getName());
                    notifyDataSetChanged();
                }
            });
            vh.btn = button;

            LinearLayout ll = convertView.findViewById(R.id.ll_item);
            vh.ll = ll;
            convertView.setTag(vh);
        } else {
            vh = (ViewHolder) convertView.getTag();
        }

        Fruit fruit = getItem(position);
        assert fruit != null;
        vh.iv.setImageResource(fruit.getImageId());
        vh.tv.setText(fruit.getName());

        if (position % 2 == 0) {
            vh.ll.setBackgroundColor(Color.rgb(0, 191, 255));
        } else {
            vh.ll.setBackgroundColor(Color.parseColor("#FFC1C1"));
        }

        vh.btn.setTag(position);
        vh.cb.setTag(position);

        Boolean b = map.get(fruit.getName());
        if (b != null) {
            vh.cb.setChecked(b);
        }
        return convertView;
    }

    void selectAll() {
        for (int i = 0; i < getCount(); i++) {
            map.put(getItem(i).getName(), true);
        }
        notifyDataSetChanged();
    }

    void selectNone() {
        for (int i = 0; i < getCount(); i++) {
            map.put(getItem(i).getName(), false);
        }
        notifyDataSetChanged();
    }

    void deleteSelected() {
        List<String> selectedFruits = new ArrayList<>();
        for (int i = 0; i < getCount(); i++) {
            String fruitName = getItem(i).getName();
            if (map.get(fruitName)) {
                selectedFruits.add(fruitName);
            }
        }
        fruitManager.deleteSelectedFruits(selectedFruits);
        notifyDataSetChanged();
    }
}

Fruit

public class Fruit {
    private String name;
    private int imageId;

    Fruit(String name, int imageId) {
        this.name = name;
        this.imageId = imageId;
    }

    public String getName() {
        return name;
    }

    int getImageId() {
        return imageId;
    }
}

FruitManager

import java.util.Iterator;
import java.util.List;

class FruitManager {
    private List<Fruit> fruitList;
    FruitManager(List<Fruit> objects) {
        fruitList = objects;
    }

    Fruit get(int i) {
        return fruitList.get(i);//List  中的元素index 0...1...2......
    }

    void deleteFruit(String fruitName) {
        Iterator<Fruit> it = fruitList.iterator();
        while (it.hasNext()) {
            if (it.next().getName().equals(fruitName)) {
                it.remove();
            }
        }
    }

    void deleteSelectedFruits(List<String> list) {
        for (int i = 0; i < list.size(); i++) {
            deleteFruit(list.get(i));
        }
    }
}

activity_mylistview.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MyListViewActivity">

    <TextView
        android:id="@+id/tv_title"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:layout_weight="0"
        android:background="#ffa6af"
        android:gravity="center"
        android:text="My Fruit ListView"
        android:textAllCaps="false"
        android:textSize="20sp" />

    <ListView
        android:id="@+id/lv_fruits"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"></ListView>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0"
        android:background="@color/colorPrimaryDark"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_deleteSelected"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="#5ddf6a"
            android:onClick="onClick"
            android:text="DeleteSelected"
            android:textAllCaps="false" />

        <Button
            android:id="@+id/btn_selectAll"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="#3dc9bc"
            android:onClick="onClick"
            android:text="SelectAll"
            android:textAllCaps="false" />

    </LinearLayout>
</LinearLayout>

myfruititem.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/ll_item"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <ImageView
        android:id="@+id/iv_fruitImage"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:contentDescription="@string/app_name" />

    <TextView
        android:id="@+id/tv_fruitName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_weight="1" />

    <CheckBox
        android:id="@+id/cb_selectItem"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_marginRight="20dp"
        android:layout_weight="0"
        android:focusable="false" />

    <Button
        android:id="@+id/btn_delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_vertical"
        android:layout_weight="0"
        android:background="#3dc9bc"
        android:focusable="false"
        android:text="Delete"
        android:textAllCaps="false"
        android:textColor="#af39e0"
        android:textSize="16sp" />

</LinearLayout>