购物车 全选逻辑

思路

• 购物车的条目采用listview 展示
• listview 条目中 checkbox 控件，该控件默认为未选中 isChecked(false);
• listview外部点击全选按钮点击后，listview 内部数据如果是未选中状态改为选中状态；再次点击则全部变为 为选中状态
  
  • listview 中checkbox 状态与 外部的全选 checkbox 的状态相同，则考虑 将 外部全选的状态赋予 listview checkbox 状态
• 更新完数据后，进行刷新
  
  • 方式一
    
    • adapter.notifyDataSetChanged();
  • 方式二 重写设置适配器 ，适配器单独写，提升为全局变量，可以保证设置的适配器均为同一个引用
    
    • listview.setAdapter(adapter);

注意事项

• 采用方式一 ，更新数据，有时数据已经刷新，但是界面没有更新，所有采用第二种方式更靠谱。

参考代码

• 代码一

  `public class MainActivity extends Activity {

  private ListView list_view;
  private CheckAdapter checkAdapter;
  private CheckBox allBox;
  private Button reverse;

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

  list_view = (ListView)findViewById(R.id.list_view);allBox = (CheckBox)findViewById(R.id.all);reverse = (Button)findViewById(R.id.reverse);List<String> list = new ArrayList<String>();for (int i = 0; i < 15; i++) {    list.add("这是条目" + i);}checkAdapter = new CheckAdapter(getApplicationContext(), list);list_view.setAdapter(checkAdapter);//设置全选allBox.setOnClickListener(new OnClickListener() {    @Override    public void onClick(View v) {        boolean flag = allBox.isChecked();        for (int i = 0; i < checkAdapter.getSelect().size(); i++) {            checkAdapter.getSelect().set(i, flag);        }        checkAdapter.notifyDataSetChanged();    }});//反选reverse.setOnClickListener(new OnClickListener() {    @Override    public void onClick(View v) {        if (! checkAdapter.getSelect().contains(true)) {            Toast.makeText(MainActivity.this, "qingxuanz", 0).show();        }else {            for (int i = 0; i < checkAdapter.getSelect().size(); i++) {                if (checkAdapter.getSelect().get(i)) {                    checkAdapter.getSelect().set(i, false);                }else {                    checkAdapter.getSelect().set(i, true);                }            }            if (checkAdapter.getSelect().contains(false)) {                allBox.setChecked(false);            }            checkAdapter.notifyDataSetChanged();        }    }});

  }

  private class CheckAdapter extends BaseAdapter {
  private List list;
  private Context context;

  //创建一个集合 去记录选中与未选中的状态 LinkedList<Boolean> linkedList = new LinkedList<Boolean>();public CheckAdapter(Context context, List<String> list) {    // TODO Auto-generated constructor stub    this.list = list;    this.context = context;    for (int i = 0; i < list.size(); i++) {        linkedList.add(false);    }}//对外提供一个方法 获取这个集合private List<Boolean> getSelect() {    return linkedList;}@Overridepublic int getCount() {    // TODO Auto-generated method stub    return list.size();}@Overridepublic Object getItem(int position) {    // TODO Auto-generated method stub    return list.get(position);}@Overridepublic long getItemId(int position) {    // TODO Auto-generated method stub    return position;}@Overridepublic View getView(final int position, View convertView,        ViewGroup parent) {    if (convertView == null) {        convertView = View.inflate(context, R.layout.item, null);    }    CheckBox ck = (CheckBox) convertView.findViewById(R.id.ck);    TextView tView = (TextView) convertView.findViewById(R.id.tv);    tView.setText(list.get(position));    ck.setChecked(linkedList.get(position));    //对checkBox点击进行监听    ck.setOnClickListener(new OnClickListener() {        @Override        public void onClick(View v) {            //点中的时候改成相反的值            linkedList.set(position, ! linkedList.get(position));            //点击的同时还要去判断全选            if (linkedList.contains(false)) {                allBox.setChecked(false);            }else {                allBox.setChecked(true);            }            notifyDataSetChanged();        }    });    return convertView;}

  }

  }
  `

• 代码二

  `
  public class Fragment3_Shopping extends Fragment implements View.OnClickListener {

  private Activity mactivity;
  private View view;
  private ListView lv_shopping;
  private MyDatabase mydb;
  private List list;
  private CheckBox cbox_shopping;
  private ImageView iv_shoping;
  private TextView tv_listitem_name;
  private TextView tv_listitem_price;
  private TextView tv_listitem_num;
  private LinearLayout ll_listitem_pics;
  private LinearLayout.LayoutParams params;
  private String tag = “Fragment3_Shopping”;
  private ShoppingAdapter adapter;
  private CheckBox cbox_all;
  private TextView tv_totalprice;
  private TextView btn_account;

  @Override
  public View onCreateView(LayoutInflater inflater, ViewGroup container,
  Bundle savedInstanceState) {
  view = inflater.inflate(R.layout.fragment_fragment3__shopping, container, false);
  mactivity = getActivity();//获取数据库对象
  mydb = new MyDatabase(mactivity);
  return view;
  }

  @Override
  public void onActivityCreated(@Nullable Bundle savedInstanceState) {
  super.onActivityCreated(savedInstanceState);
  initView();//初始化控件
  initData();//初始化数据
  }

  private void initData() {
  list = new ArrayList();
  SQLiteDatabase db = mydb.getWritableDatabase();

  Cursor cursor = db.query("shopping", null, null, null, null, null, null);ShoppingBean shoppingBean = null;while (cursor.moveToNext()) {    shoppingBean = new ShoppingBean();    shoppingBean.id = cursor.getInt(cursor.getColumnIndex("_id"));    shoppingBean.goods_name = cursor.getString(cursor.getColumnIndex("goods_name"));    shoppingBean.shop_price = cursor.getInt(cursor.getColumnIndex("shop_price"));    shoppingBean.numShow = cursor.getInt(cursor.getColumnIndex("numShow"));    shoppingBean.goodsimg = cursor.getString(cursor.getColumnIndex("goods_img"));    shoppingBean.is_activity_goods = cursor.getString(cursor.getColumnIndex("is_activity_goods"));    shoppingBean.is_allow_credit = cursor.getString(cursor.getColumnIndex("is_allow_credit"));    shoppingBean.url = cursor.getString(cursor.getColumnIndex("url"));    list.add(shoppingBean);}Log.e(tag, list.toString());adapter = new ShoppingAdapter(list);lv_shopping.setAdapter(adapter);

  }

  private void initView() {
  lv_shopping = (ListView) view.findViewById(R.id.lv_shopping);
  cbox_all = (CheckBox) view.findViewById(R.id.cbox_all_shopping);
  tv_totalprice = (TextView) view.findViewById(R.id.tv_totalprice_shopping);
  btn_account = (TextView) view.findViewById(R.id.btn_account_shopping);
  cbox_all.setOnClickListener(this);
  }

  @Override
  public void onClick(View v) {
  switch (v.getId()) {
  case R.id.cbox_all_shopping://全选，要么全true，要么全false
  Log.i(“–”, “cbox_all—” + cbox_all.isChecked());
  boolean flag = cbox_all.isChecked();

          for (int i = 0; i < adapter.getList().size(); i++) {            adapter.getList().set(i, flag);        }        lv_shopping.setAdapter(adapter);        //-----------------每次点击为0        tv_totalprice.setText("￥" + adapter.getTotalprice());        break;    default:        break;}

  }

  class ShoppingAdapter extends BaseAdapter {//设置适配器

  List<ShoppingBean> list;private LinkedList<Boolean> linkedList = new LinkedList<Boolean>();public ShoppingAdapter(List<ShoppingBean> list) {    this.list = list;    for (int i = 0; i < list.size(); i++) {        linkedList.add(false);    }}private List<Boolean> getList() {    return linkedList;}private double getTotalprice() {    double  totalprice = 0;    for (int i = 0; i < linkedList.size(); i++) {        ShoppingBean shoppingBean = list.get(i);        if (linkedList.get(i)) {            totalprice += shoppingBean.shop_price * shoppingBean.numShow;        }    }    return totalprice;}@Overridepublic int getCount() {    return list.size();}@Overridepublic Object getItem(int position) {    return list.get(position);}@Overridepublic long getItemId(int position) {    return position;}@Overridepublic View getView(final int position, View convertView, ViewGroup parent) {    if (convertView == null) {        convertView = View.inflate(mactivity, R.layout.listitem_shopping, null);        cbox_shopping = (CheckBox) convertView.findViewById(R.id.cbox_shopping);        iv_shoping = (ImageView) convertView.findViewById(R.id.iv_shoping);        tv_listitem_name = (TextView) convertView.findViewById(R.id.tv_listitem_name);        tv_listitem_price = (TextView) convertView.findViewById(R.id.tv_listitem_price);        tv_listitem_num = (TextView) convertView.findViewById(R.id.tv_listitem_num);        ll_listitem_pics = (LinearLayout) convertView.findViewById(R.id.ll_listitem_pics);    }    //处理点击事件  判断如果外部选择，则    cbox_shopping.setChecked(linkedList.get(position));    ShoppingBean shoppingBean = list.get(position);    BitmapUtils bit = new BitmapUtils(mactivity);    bit.display(iv_shoping, shoppingBean.goodsimg);//商品图片    tv_listitem_name.setText(shoppingBean.goods_name);//商品名称    tv_listitem_price.setText("￥" + shoppingBean.shop_price);    tv_listitem_num.setText("数量：" + shoppingBean.numShow);    String is_allow_credit = shoppingBean.is_allow_credit;    String is_activity_goods = shoppingBean.is_activity_goods;    //---------------------    cbox_shopping.setOnClickListener(new View.OnClickListener() {        @Override        public void onClick(View v) {            linkedList.set(position, !linkedList.get(position));//点击取反            //如果全选，则全选按钮选择            if (linkedList.contains(false)) {                cbox_all.setChecked(false);            } else {                cbox_all.setChecked(true);            }            notifyDataSetChanged();            tv_totalprice.setText("￥" + getTotalprice());        }    });    if (ll_listitem_pics.getChildCount() > 0) {        ll_listitem_pics.removeAllViews();    }    if (is_activity_goods.equals("0")) {        ImageView img1 = new ImageView(mactivity);        params = new LinearLayout.LayoutParams(20, 20);        params.leftMargin = 10;        img1.setLayoutParams(params);        img1.setBackgroundResource(R.drawable.coupons);        ll_listitem_pics.addView(img1);    }    if (is_allow_credit.equals("True")) {        ImageView img1 = new ImageView(mactivity);        params = new LinearLayout.LayoutParams(20, 20);        params.leftMargin = 10;        img1.setLayoutParams(params);        img1.setBackgroundResource(R.drawable.pledge);        ll_listitem_pics.addView(img1);    }    return convertView;}

  }
  }

  `