家庭记账本（五）主界面完善

　　之前我们已经实现可以将账单信息录入数据库中。在之前的设计中，我们要想在主界面显示这些保存的信息，那么现在首先来完善主界面，让主界面可以正常显示。

　　之前的编写时我们已经知道，主界面大部分是有一个ListView来显示。首先我们就需要创建一个这个的适配器。

public class AccountAdapter extends BaseAdapter {

    Context context;
    List<AccountBean> mDatas;
    int year, month, day;

    public AccountAdapter(Context context, List<AccountBean> mDatas) {
        this.context = context;
        this.mDatas = mDatas;

        Calendar calendar = Calendar.getInstance();
        year = calendar.get(Calendar.YEAR);
        month = calendar.get(Calendar.MONTH)+1;
        day = calendar.get(Calendar.DAY_OF_MONTH);
    }

    @Override
    public int getCount() {
        return mDatas.size();
    }

    @Override
    public Object getItem(int position) {
        return mDatas.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.item_mainlv, parent, false);

            viewHolder = new ViewHolder(convertView);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        AccountBean bean = mDatas.get(position);
        viewHolder.iv_type.setImageResource(bean.getsImageId());
        viewHolder.tv_type.setText(bean.getTypename());
        viewHolder.tv_mark.setText(bean.getMark());
        if (bean.getKind() == 1) {
            viewHolder.tv_money.setText(" +"+bean.getMoney());
        } else {
            viewHolder.tv_money.setText(" -"+bean.getMoney());
        }


        if (bean.getYear()==year&&bean.getMonth()==month&&day==bean.getDay()) {
            String time = bean.getTime().split(" ")[1];
            viewHolder.tv_time.setText("今天 "+time);
        } else {
            viewHolder.tv_time.setText(bean.getTime());
        }

        return convertView;
    }

    class ViewHolder {
        ImageView iv_type;
        TextView tv_type, tv_mark, tv_time, tv_money;

        public ViewHolder(View view) {
            iv_type = view.findViewById(R.id.item_mainlv_iv);
            tv_type = view.findViewById(R.id.item_mainlv_title);
            tv_mark = view.findViewById(R.id.item_mainlv_tv_mark);
            tv_time = view.findViewById(R.id.item_mainlv_tv_time);
            tv_money = view.findViewById(R.id.item_mainlv_tv_money);
        }
    }
}

　　使用ViewHolder实现当数据多时实现向下翻阅。

 /*设置适配器，加载每一行的数据*/
        adapter = new AccountAdapter(this, mDats);
        lv_today_info.setAdapter(adapter);

　　在onResume中加载需要显示的数据。onResume是在获取焦点时。

/*当Activity获取焦点时会调用的方法*/
    @Override
    protected void onResume() {
        super.onResume();
        loadDBData();
    }

　　添加方法在数据库中添加查找所有账单信息的方法。

/*获取记账表中某一天的所有支出或者记账情况*/
    public static List<AccountBean> getAccountListOneDay(int year, int month, int day){
        ArrayList<AccountBean> list = new ArrayList<>();

        String sql = "select * from tb_account where year=? and month=? and day=? order by id desc";
        Cursor cursor = db.rawQuery(sql, new String[]{String.valueOf(year), String.valueOf(month), String.valueOf(day)});

        /*遍历符合要求的每一行数据*/
        while (cursor.moveToNext()) {
            int id = cursor.getInt(cursor.getColumnIndex("id"));
            String typename = cursor.getString(cursor.getColumnIndex("typename"));
            String mark = cursor.getString(cursor.getColumnIndex("mark"));
            String time = cursor.getString(cursor.getColumnIndex("time"));
            int sImageId = cursor.getInt(cursor.getColumnIndex("sImageId"));
            int kind = cursor.getInt(cursor.getColumnIndex("kind"));
            float money = cursor.getFloat(cursor.getColumnIndex("money"));

            AccountBean accountBean = new AccountBean(id, typename, sImageId, mark, money, time, year, month, day, kind);
            list.add(accountBean);

        }

        return list;
    }

    public void loadDBData() {
        List<AccountBean> list = DBManager.getAccountListOneDay(year, month, day);
        mDats.clear();
        mDats.addAll(list);
        adapter.notifyDataSetChanged();
    }