展示效果

主Activity中的方法

public class MainActivity extends Activity implements ShopcartExpandableListViewAdapter.CheckInterface, ShopcartExpandableListViewAdapter.ModifyCountInterface, OnClickListener
{
    private ExpandableListView exListView;
    private CheckBox cb_check_all;
    private TextView tv_total_price;
    private
 
 TextView tv_delete;
    private TextView tv_go_to_pay;
    private Context context;

    private double totalPrice = 0.00;// 購買的商品總價
    private int totalCount = 0;// 購買的商品總數量

    private ShopcartExpandableListViewAdapter selva;
    private List<GroupInfo> groups = new ArrayList<GroupInfo>();// 組元素資料列表
 

    private Map<String, List<ProductInfo>> children = new HashMap<String, List<ProductInfo>>();// 子元素資料列表

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        initView();
        initEvents();
    }

    private
 
 void initView()
    {
        context = this;
        virtualData();
        exListView = (ExpandableListView) findViewById(R.id.exListView);
        cb_check_all = (CheckBox) findViewById(R.id.all_chekbox);
        tv_total_price = (TextView) findViewById(R.id.tv_total_price);
        tv_delete = (TextView) findViewById(R.id.tv_delete);
        tv_go_to_pay = (TextView) findViewById(R.id.tv_go_to_pay);
    }

    private void initEvents()
    {
        selva = new ShopcartExpandableListViewAdapter(groups, children, this);
        selva.setCheckInterface(this);// 關鍵步驟1,設定複選框介面
        selva.setModifyCountInterface(this);// 關鍵步驟2,設定數量增減介面
        exListView.setAdapter(selva);

        for (int i = 0; i < selva.getGroupCount(); i++)
        {
            exListView.expandGroup(i);// 關鍵步驟3,初始化時，將ExpandableListView以展開的方式呈現
        }

        cb_check_all.setOnClickListener(this);
        tv_delete.setOnClickListener(this);
        tv_go_to_pay.setOnClickListener(this);
    }

    /**
     * 模擬資料<br>
     * 遵循介面卡的資料列表填充原則，組元素被放在一個List中，對應的組元素下轄的子元素被放在Map中，<br>
     * 其鍵是組元素的Id(通常是一個唯一指定組元素身份的值)
     */
    private void virtualData()
    {

        for (int i = 0; i < 6; i++)
        {

            groups.add(new GroupInfo(i + "", "第八號當鋪" + (i + 1) + "號店"));

            List<ProductInfo> products = new ArrayList<ProductInfo>();
            for (int j = 0; j <= i; j++)
            {

                products.add(new ProductInfo(j + "", "商品", "", groups.get(i).getName() + "的第" + (j + 1) + "個商品", 120.00 + i * j, 1));
            }
            children.put(groups.get(i).getId(), products);// 將組元素的一個唯一值，這裡取Id，作為子元素List的Key
        }
    }

    @Override
    public void onClick(View v)
    {
        AlertDialog alert;
        switch (v.getId())
        {
            case R.id.all_chekbox:
                doCheckAll();
                break;
            case R.id.tv_go_to_pay:
                if (totalCount == 0)
                {
                    Toast.makeText(context, "請選擇要支付的商品", Toast.LENGTH_LONG).show();
                    return;
                }
                alert = new AlertDialog.Builder(context).create();
                alert.setTitle("操作提示");
                alert.setMessage("總計:\n" + totalCount + "種商品\n" + totalPrice + "元");
                alert.setButton(DialogInterface.BUTTON_NEGATIVE, "取消", new DialogInterface.OnClickListener()
                {
                    @Override
                    public void onClick(DialogInterface dialog, int which)
                    {
                        return;
                    }
                });
                alert.setButton(DialogInterface.BUTTON_POSITIVE, "確定", new DialogInterface.OnClickListener()
                {
                    @Override
                    public void onClick(DialogInterface dialog, int which)
                    {
                        return;
                    }
                });
                alert.show();
                break;
            case R.id.tv_delete:
                if (totalCount == 0)
                {
                    Toast.makeText(context, "請選擇要移除的商品", Toast.LENGTH_LONG).show();
                    return;
                }
                alert = new AlertDialog.Builder(context).create();
                alert.setTitle("操作提示");
                alert.setMessage("您確定要將這些商品從購物車中移除嗎？");
                alert.setButton(DialogInterface.BUTTON_NEGATIVE, "取消", new DialogInterface.OnClickListener()
                {
                    @Override
                    public void onClick(DialogInterface dialog, int which)
                    {
                        return;
                    }
                });
                alert.setButton(DialogInterface.BUTTON_POSITIVE, "確定", new DialogInterface.OnClickListener()
                {
                    @Override
                    public void onClick(DialogInterface dialog, int which)
                    {
                        doDelete();
                    }
                });
                alert.show();
                break;
        }
    }

    /**
     * 刪除操作<br>
     * 1.不要邊遍歷邊刪除，容易出現數組越界的情況<br>
     * 2.現將要刪除的物件放進相應的列表容器中，待遍歷完後，以removeAll的方式進行刪除
     */
    protected void doDelete()
    {
        List<GroupInfo> toBeDeleteGroups = new ArrayList<GroupInfo>();// 待刪除的組元素列表
        for (int i = 0; i < groups.size(); i++)
        {
            GroupInfo group = groups.get(i);
            if (group.isChoosed())
            {

                toBeDeleteGroups.add(group);
            }
            List<ProductInfo> toBeDeleteProducts = new ArrayList<ProductInfo>();// 待刪除的子元素列表
            List<ProductInfo> childs = children.get(group.getId());
            for (int j = 0; j < childs.size(); j++)
            {
                if (childs.get(j).isChoosed())
                {
                    toBeDeleteProducts.add(childs.get(j));
                }
            }
            childs.removeAll(toBeDeleteProducts);

        }

        groups.removeAll(toBeDeleteGroups);

        selva.notifyDataSetChanged();
        calculate();
    }

    @Override
    public void doIncrease(int groupPosition, int childPosition, View showCountView, boolean isChecked)
    {

        ProductInfo product = (ProductInfo) selva.getChild(groupPosition, childPosition);
        int currentCount = product.getCount();
        currentCount++;
        product.setCount(currentCount);
        ((TextView) showCountView).setText(currentCount + "");

        selva.notifyDataSetChanged();
        calculate();
    }

    @Override
    public void doDecrease(int groupPosition, int childPosition, View showCountView, boolean isChecked)
    {

        ProductInfo product = (ProductInfo) selva.getChild(groupPosition, childPosition);
        int currentCount = product.getCount();
        if (currentCount == 1)
            return;
        currentCount--;

        product.setCount(currentCount);
        ((TextView) showCountView).setText(currentCount + "");

        selva.notifyDataSetChanged();
        calculate();
    }

    @Override
    public void checkGroup(int groupPosition, boolean isChecked)
    {
        GroupInfo group = groups.get(groupPosition);
        List<ProductInfo> childs = children.get(group.getId());
        for (int i = 0; i < childs.size(); i++)
        {
            childs.get(i).setChoosed(isChecked);
        }
        if (isAllCheck())
            cb_check_all.setChecked(true);
        else
            cb_check_all.setChecked(false);
        selva.notifyDataSetChanged();
        calculate();
    }

    @Override
    public void checkChild(int groupPosition, int childPosiTion, boolean isChecked)
    {
        boolean allChildSameState = true;// 判斷改組下面的所有子元素是否是同一種狀態
        GroupInfo group = groups.get(groupPosition);
        List<ProductInfo> childs = children.get(group.getId());
        for (int i = 0; i < childs.size(); i++)
        {
            if (childs.get(i).isChoosed() != isChecked)
            {
                allChildSameState = false;
                break;
            }
        }
        if (allChildSameState)
        {
            group.setChoosed(isChecked);// 如果所有子元素狀態相同，那麼對應的組元素被設為這種統一狀態
        } else
        {
            group.setChoosed(false);// 否則，組元素一律設定為未選中狀態
        }

        if (isAllCheck())
            cb_check_all.setChecked(true);
        else
            cb_check_all.setChecked(false);
        selva.notifyDataSetChanged();
        calculate();
    }

    private boolean isAllCheck()
    {

        for (GroupInfo group : groups)
        {
            if (!group.isChoosed())
                return false;

        }

        return true;
    }

    /** 全選與反選 */
    private void doCheckAll()
    {
        for (int i = 0; i < groups.size(); i++)
        {
            groups.get(i).setChoosed(cb_check_all.isChecked());
            GroupInfo group = groups.get(i);
            List<ProductInfo> childs = children.get(group.getId());
            for (int j = 0; j < childs.size(); j++)
            {
                childs.get(j).setChoosed(cb_check_all.isChecked());
            }
        }
        selva.notifyDataSetChanged();
    }

    /**
     * 統計操作<br>
     * 1.先清空全域性計數器<br>
     * 2.遍歷所有子元素，只要是被選中狀態的，就進行相關的計算操作<br>
     * 3.給底部的textView進行資料填充
     */
    private void calculate()
    {
        totalCount = 0;
        totalPrice = 0.00;
        for (int i = 0; i < groups.size(); i++)
        {
            GroupInfo group = groups.get(i);
            List<ProductInfo> childs = children.get(group.getId());
            for (int j = 0; j < childs.size(); j++)
            {
                ProductInfo product = childs.get(j);
                if (product.isChoosed())
                {
                    totalCount++;
                    totalPrice += product.getPrice() * product.getCount();
                }
            }
        }
        tv_total_price.setText("￥" + totalPrice);
        tv_go_to_pay.setText("去支付(" + totalCount + ")");
    }
}

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