java判断字符串是否是日期

public class DateUtil {
    private static final SimpleDateFormat dateFormat = null;
    static {
        dateFormat = new SimpleDateFormat("yyyy/MM/dd");
        dateFormat.setLenient(false);
    }
    public static boolean isValidDate(String s) {
        try {
            dateFormat.parse(s);
            return true;
        } catch(Exception e) {
            return false;
        }
    }
    public static String formatDate(Date d) {
        return dateFormat.format(d);
    }
}