java - 获取正确的 DAY_OF_WEEK 字符串

Question

我遇到的问题是，尽管今天是星期一，但我的查询mon-fri 也总是得到天sun。在我的代码中，WDay 的值为 2 因此我构建了这样的 switch case 结构，所以我今天应该得到值 mon-fri 而不是 sun?

Calendar calendar = Calendar.getInstance();
    int WDay = calendar.get(Calendar.DAY_OF_WEEK); //Here day has the value 2.

    // Create a statement
    Statement stt = con.createStatement();

    DatabaseMetaData dbm = con.getMetaData();

    ResultSet stopsExist = dbm.getTables(null, null, "stops", null);

    if (stopsExist.next()) {
        // the stops and arrrivaltimes tables exist.

        PreparedStatement preparedLatLong = con
                .prepareStatement("SELECT lat, longi, name from stops");
        ResultSet rsLatLong = preparedLatLong.executeQuery();
        while (rsLatLong.next()) {
            double lat_stop = rsLatLong.getDouble("lat");
            double lon_stop = rsLatLong.getDouble("longi");
            double distStops = haversineDistance(latD, longD, lat_stop,
                    lon_stop);
            if (distStops <= 10) {
                String stop_name = rsLatLong.getString("name");

                String day = "";
                switch (WDay) {
                case 2:
                    day = "mon-fri";
                case 3:
                    day = "mon-fri";
                case 4:
                    day = "mon-fri";
                case 5:
                    day = "mon-fri";
                case 6:
                    day = "mon-fri";
                case 7:
                    day = "sat";
                case 1:
                    day = "sun";

                }
                 //In the query here, day has the string sun instead of mon-fri
                PreparedStatement preparedTime = con
                        .prepareStatement("SELECT route from arrivaltimes INNER JOIN stops"
                                + " ON arrivaltimes.stop_id=stops.stop_id "
                                + "WHERE weekday = '" + day + "'"
                                + " and time_format(arrivaltime,'%H:%i')= time_format(curtime() ,'%H:%i') and name LIKE '" + stop_name + "'");

Answer 1

问题出在您的switch 语句中。如果您不在每个案例之后添加 break;，您的代码将继续执行下一个案例。

这应该可以解决它:

            switch (WDay) {
            case 2:
                day = "mon-fri";
                break;
            case 3:
                day = "mon-fri";
                break;
            case 4:
                day = "mon-fri";
                break;
            case 5:
                day = "mon-fri";
                break;
            case 6:
                day = "mon-fri";
                break;
            case 7:
                day = "sat";
                break;
            case 1:
                day = "sun";
                break;

            }