判断设置的时间是否大于当前时间

import com.example.demo.Demo.dto.Student;
 
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
 
public class Test03 {
    private final static DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
 
    public static void main(String[] args) throws ParseException {
 
        //TODO 设置当前时间    return 当前时间: 2021-07-06 11:37:17 没有超过今天
        String str = "2021-07-06 11:37:17";
 
        Student student = new Student();
        student.setId(24);
        student.setName("瑶瑶");
        student.setBirthday(dateFormat.parse(str));
 
        System.err.println(f(student));
    }
 
 
    private static String f(Student student) {
        Date now;
        Calendar c = Calendar.getInstance();
        try {
            //获取当前日期
            now = new Date(c.get(Calendar.YEAR), c.get(Calendar.MONTH) + 1, c.get(Calendar.DAY_OF_MONTH));
            //截取前端传的日期
            String format = dateFormat.format(student.getBirthday());
            //截取前端传的日期
            Date createDateResource = new Date(Integer.parseInt(format.substring(0, 4)), Integer.parseInt(format.substring(5, 7)), Integer.parseInt(format.substring(8, 10)));
            if (createDateResource.after(now)) {
                //创建时间不能大于当前时间
                return "当前时间: " + format + " 超过了今天";
            } else {
                return "当前时间: " + format + " 没有超过今天";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }
}