单击按钮时更新时间

Question

I want to have it so when i click the button the time will update. Can i have a hint or help into how i would accomplish this, if what i am wanting is at all possible.

I have been struggling to do this for the last couple of days so any help would be greatly appreciated.

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.*;
import javax.swing.*;
import static javax.swing.BoxLayout.X_AXIS;
import static javax.swing.BoxLayout.Y_AXIS;

public class CountdownNBA2K16 extends JFrame implements ActionListener{

        JLabel displayDate ;
        JLabel displayDateS ;
        JLabel displayDateM ;
        JLabel displayDateH ;
        JLabel displayDateD ;

        JPanel Mili = new JPanel();
        JPanel Sec = new JPanel();
        JPanel minute = new JPanel();
        JPanel hours = new JPanel();
        JPanel day = new JPanel();
        JPanel cd = new JPanel();
        JPanel combine = new JPanel();

        JButton button = new JButton("update time");

        Calendar releaseDate;
        Calendar todayDate;

        long diff;
        long diffSec;
        long days;
        long secDays;
        long secs;
        long min;
        long hour;

        int SECONDS_IN_A_DAY = 24 * 60 * 60;

        String ms;
        String s;
        String m;
        String h;
        String d;

    public CountdownNBA2K16() {
        super("COUNTDOWN TO NBA2K16");//sets title of app

        setLayout(new FlowLayout());

                button.addActionListener(this);

                releaseDate = Calendar.getInstance();
                releaseDate.set(Calendar.DAY_OF_MONTH,25);
                releaseDate.set(Calendar.MONTH,8);
                releaseDate.set(Calendar.YEAR,2015);

                todayDate = Calendar.getInstance();
                diff = releaseDate.getTimeInMillis() - todayDate.getTimeInMillis();
                diffSec = diff/1000;

                days = diffSec / SECONDS_IN_A_DAY;
                secDays = diffSec % SECONDS_IN_A_DAY;
                secs =  secDays % 60;
                min = (secDays%60) %60;
                hour = (secDays/3600);

                s = String.valueOf(secs);
                displayDateS = new JLabel("seconds:"+s + "");

                m = String.valueOf(min);
                displayDateM = new JLabel("minutes:"+m +"");

                h = String.valueOf(hour);
                displayDateH = new JLabel("hours:"+h+"");

                d = String.valueOf(days);
                displayDateD = new JLabel("days:"+d+"");

                Sec.add(displayDateS);
                minute.add(displayDateM);
                hours.add(displayDateH);
                day.add(displayDateD);

                cd.add(day);
                cd.add(hours);
                cd.add(minute);
                cd.add(Sec);
                cd.setLayout( new BoxLayout(cd ,X_AXIS));

                combine.add(button);
                combine.add(cd);
                combine.setLayout( new BoxLayout(combine ,Y_AXIS));

                add(combine);

                pack();

                setSize(300,300);
                setResizable(false);//doesnt let user resize the gui
        setLocationRelativeTo(null);//sets location relative to nothing
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//makes the applictaion close when the gui is closed

    }
        @Override
    public void actionPerformed(ActionEvent e) {

            displayDateS.getText();
            displayDateM.getText();
            displayDateH.getText();
            displayDateD.getText();    
        }

    public static void main(String[] args) {

       SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new CountdownNBA2K16().setVisible(true);
            }
        });
    }

}

Answer 1

Start by using something like Java 8's Time API or Joda-Time to calculate the duration.

Separate the logic for the duration calculation to a separate method, this way you can call it from both the constructor and the actionPerformed method.

Something like...

protected void updateDuration() {
    System.out.println(LocalDateTime.now());
    Duration d = Duration.between(releaseDate.atStartOfDay(), LocalDateTime.now());
    System.out.println(d.toMillis());
    long days = d.toDays();
    d = d.minusDays(days);
    long hours = d.toHours();
    d = d.minusHours(hours);
    long mins = d.toMinutes();
    d = d.minusMinutes(mins);
    long seconds = d.toMillis() / 1000;

    displayDateS.setText("Seconds: " + seconds);
    displayDateM.setText("Minutes: " + mins);
    displayDateH.setText("Hours: " + hours);
    displayDateD.setText("Days: " + days);
}

for example (just make sure you've created the labels before you call it)

You might also like to have a look at How to use Swing Timers to update the output automatically.

Answer 2

Analogy just. Because still I am unable to post comment that is why I answered you. In the actionPerformed method just set the text of the labels to what you want.

public class CountdownNBA2K16 extends JFrame implements ActionListener {

    JLabel displayTime;
    JButton button = new JButton("Update time");

    public CountdownNBA2K16() {
        super("Time");
        setLayout(new FlowLayout());
        button.addActionListener(this);
        displayTime = new JLabel("Just to see the updates ..." + System.currentTimeMillis());
        setSize(300, 300);
        add(displayTime);
        add(button);
        pack();
        setResizable(false);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    }

    @Override
    public void actionPerformed(ActionEvent e) {
        displayTime.setText("Just to see the updates ..." + System.currentTimeMillis());
    }

    public static void main(String[] args) {

        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                new CountdownNBA2K16().setVisible(true);
            }
        });
    }

}