java - 更新日历

Question

我对编程相当陌生，目前正在学习它的整个面向对象方面。但我对如何更新我的日历对象一无所知。不太确定我的更新方法需要什么来更新日历。下面是我正在使用的两个类。

public class Time {
    private int hour;
    private int minute;
    private int second;
    Calendar cal = Calendar.getInstance();

    public Time(){
        Calendar cal = Calendar.getInstance();
        this.hour = cal.get(Calendar.HOUR_OF_DAY);
        this.minute = cal.get(Calendar.MINUTE);
        this.second = cal.get(Calendar.SECOND);
    }
    public int getHour(){
        return this.hour;
    }
    public int getMinute(){
        return this.minute;
    }
    public int getSecond(){
        return this.second;
    }
    public String toString(){
        return this.hour + ":" + this.minute + ":" + this.second;
    }
    public void update(){
        cal.setTime(new Date());    
    }
}

这是我的主要类(class):

public class Exercise2b {
    public void demo() {
        String message1, message2;
        int hour, minute, second;
        Time dt = new Time();
        hour = dt.getHour();
        minute = dt.getMinute();
        second = dt.getSecond();
        message1 = "Klockan är " + minute + " minuter över " + hour + " (+" + second + " sekunder)";
        message2 = dt.toString();
        JOptionPane.showMessageDialog(null, message1);
        JOptionPane.showMessageDialog(null, message2);
        dt.update();
        message2 = dt.toString();
        JOptionPane.showMessageDialog(null, message2);
    }

    public static void main(String[] args) {  
        Exercise2b prog = new Exercise2b();
        prog.demo();    
        }
    }

任何帮助将不胜感激!

Answer 1

在更新函数中，您仅更新 cal 的实例。您还必须更新小时、分钟和秒变量。你可以这样做。

public void update(){
    cal.setTime(new Date());  
    this.hour = cal.get(Calendar.HOUR_OF_DAY);
    this.minute = cal.get(Calendar.MINUTE);
    this.second = cal.get(Calendar.SECOND);
}

要获得时间差，您可以使用Thread.Sleep()

import javax.swing.*;
public class Exercise2b {
public void demo() {
    String message1, message2;
    int hour, minute, second;
    Time dt = new Time();
    hour = dt.getHour();
    minute = dt.getMinute();
    second = dt.getSecond();
    message1 = "Klockan är" +minute+"minuter över"+hour+"(+"+second+"sekunder)";
    message2 = dt.toString();
    JOptionPane.showMessageDialog(null, message1);
    JOptionPane.showMessageDialog(null, message2);

    try
    {
        Thread.sleep(5000);
    }
    catch(Exception e)
    {
        System.out.println("Exception Occured");
    }

    dt.update();

    message2 = dt.toString();
    JOptionPane.showMessageDialog(null, message2);

}

public static void main(String[] args) {  
    Exercise2b prog = new Exercise2b();
    prog.demo();    
    }
}