Calculate elapsed time of ClockAnimation class

Question

I want to add a panel to my ClockAnimation class that displays the time which the clock was started, the time which the clock was stopped, and the time elapsed from start to stop. I would really like it to be in the format of Hour:Minute:Second. Any Help would be appreciated.

My ClockAnimation class:

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;

public class ClockAnimation extends JFrame
{
   //create an instance for StillClock
   private StillClock clock = new StillClock();

   //create buttons
   JButton startButton;
   JButton stopButton;

   //create a timer (1000 milliseconds delay)
   Timer timer = new Timer(1000, new TimerListener());

   public ClockAnimation()
   {
      //create a panel to hold the clock
      JPanel clockPanel = new JPanel();

      //add the clock to panel
      clockPanel.add(clock);

     //create a panel to hold start and stop buttons
      JPanel ButtonPanel = new JPanel();

     //create a start button
      startButton = new JButton("Start");
     //add action listener to startButton
      startButton.addActionListener(new startListener());
     //create a stop button
      stopButton = new JButton("Stop");
     //add action listener to stopButton
      stopButton.addActionListener(new stopListener());
     //add start button to ButtonPanel
      ButtonPanel.add(startButton);
     //add stop button to ButtonPanel
      ButtonPanel.add(stopButton);

      //create elapsedPanel to hold elaped time
      JPanel ElspsedPanel = new JPanel();

      //add start time to panel
      add.(timer.start());
      //add stop time to panel
      add.(timer.stop());
      //add the elapsed time to panel
      ElapsedPanel.add((timer.start())-(timer.stop()));


   //add the clockPanel and ButtonPanel to the frame
      add(clockPanel, BorderLayout.NORTH);
      add(ButtonPanel, BorderLayout.CENTER);
      add(ElapsedPanel, BorderLayout.SOUTH);
   }

   private class startListener implements ActionListener
   {
      public void actionPerformed(ActionEvent e)
      {
         //start clock time
         timer.start();
      }
   }

   private class stopListener implements ActionListener
   {
      public void actionPerformed(ActionEvent e)
      {
         //stop clock time
         timer.stop();
      }
   }

   private class TimerListener implements ActionListener
   {
      public void actionPerformed(ActionEvent e)
      {
         //set current time and paint clock to display current time
         clock.setCurrentTime();
         clock.repaint();
      }
   }

   //main method  
   public static void main(String[] args)
   {
  //create a JFrame instance
  JFrame frame = new ClockAnimation();

     //set title of the frame
  frame.setTitle("My Clock");
     //set location of the frame to center
  frame.setLocationRelativeTo(null);
     //set frame to close on exit
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     //set frame to visable
  frame.setVisible(true);
     //set components to fit in frame
  frame.pack();
   }
}

My ClockAnimation class uses my StillClock class:

import java.awt.event.*;
import javax.swing.*;
import java.awt.*;
import java.util.*;

public class StillClock extends JPanel
{
   //create variables for StillClock
   public int hour;
   private int minute;
   private int second;

   //create a clock with current time
   public StillClock()
   {
  setCurrentTime();
   }

   //create a clock with specified time
   public StillClock(int hour, int minute, int second)
   {
      this.hour = hour;
      this.minute = minute;
      this.second = second;
   }

   //return hour
   public int getHour()
   {
  return hour;
   }

   //set new hour
   public void setHour(int hour)
   {
      this.hour = hour;
  repaint();
   }

    //return minutes
   public int getMinute()
   {
      return minute;
   }

     //set new minute
   public void setMinute(int minute)
   {
      this.minute = minute;
      repaint();
   }

    //return seconds
   public int getSecond()
   {
      return second;
   }

     //set new second
   public void setSecond(int second)
   {
      this.second = second;
      repaint();
   }

   //draw the clock 
   protected void paintComponent(Graphics g)
   {
  super.paintComponent(g);

  int clockRadius = (int)(Math.min(getWidth(), getHeight()) * 0.8 * 0.5);
  int xCenter = getWidth()/ 2;
  int yCenter = getHeight() / 2;

   //draw clock circle
  g.setColor(Color.BLACK);
  g.drawOval(xCenter - clockRadius, yCenter - clockRadius, 2 * clockRadius, 2 * clockRadius);

  g.drawString("12", xCenter - 5, yCenter - clockRadius + 13);
  g.drawString("9", xCenter - clockRadius + 3, yCenter + 5);
  g.drawString("3", xCenter + clockRadius - 10, yCenter + 3);
  g.drawString("6", xCenter - 3, yCenter + clockRadius - 3);

   //draw seconds hand
  int sLength = (int)(clockRadius * 0.8);
  int xSecond = (int)(xCenter + sLength * Math.sin(second * (2 * Math.PI/ 60)));
  int ySecond = (int)(yCenter - sLength * Math.cos(second * (2 * Math.PI/ 60)));
  g.drawLine(xCenter, yCenter, xSecond, ySecond);
  g.setColor(Color.red);

   //draw minutes hand
  int mLength = (int)(clockRadius * 0.65);
  int xMinute = (int)(xCenter + mLength * Math.sin(minute * (2 * Math.PI/ 60)));
  int yMinute = (int)(yCenter - mLength * Math.cos(minute * (2 * Math.PI/ 60)));
  g.drawLine(xCenter, yCenter, xMinute, yMinute);
  g.setColor(Color.lightGray);

   //draw hours hand
  int hLength = (int)(clockRadius * 0.8);
  int xHour = (int)(xCenter + hLength * Math.sin(hour * (2 * Math.PI/ 60)));
  int yHour = (int)(yCenter - hLength * Math.cos(hour * (2 * Math.PI/ 60)));
  g.drawLine(xCenter, yCenter, xHour, yHour);
  g.setColor(Color.darkGray);
   }

     //set current time to StillClock variables
   public void setCurrentTime()
   {
   //construct calendar for current time and date
  Calendar calendar = new GregorianCalendar();

   //set current time
  this.hour = calendar.get(Calendar.HOUR_OF_DAY);
  this.minute = calendar.get(Calendar.MINUTE);
  this.second = calendar.get(Calendar.SECOND);
   }

 //get dimensions of JPanel
   public Dimension getPreferredSize()
   {
  return new Dimension(200, 200);
   }
}

I have pretty much tried everything I can think of. My assignment that this is for has been fulfilled without displaying these times but I think it would be cool to learn how to add this in. Thanks, Samantha

Answer 1

I am not an expert, but from what I can tell, the best way would be to get the elapsed time is by using System.currentTimeMillis() when you start and when you stop the timer. You can then Subtract the second value from the first in order to find the elapsed time in milliseconds, and then simply divide by 1000 to get seconds.

Example:

int startTime;
double currentElapsedTime;
double endElapsedTime;

void start()
{
  timer.start();
  startTime = System.currentTimeMillis();
}

void stop()
{
  timer.stop();
  elapsedTime = getElapsedTime();
}

void getElapsedTime()        //Could be called apart from the stop() function to 
                             //get the elapsed time without stopping the timer
{                              
  currentElapsedTime = (System.currentTimeMillis() - startTime)/1000;
}

This is just a snippet, and I know it's not perfect, but this is the best way I know to do it.

In order to get hours and minutes, you would simply take the endElapsedTime and divide it by 60 to get minutes while the remainder would be the seconds. Repeat this process to get the time in hours too, but the remainder would be the minutes instead of the seconds.

String toStandardTime(double elapsedTime)
{
  int hours = 0;
  int minutes = 0;
  int seconds = 0;
  String formattedTime;

  minutes = (int) t/60;
  seconds = (int) t%60;
  hours = (int) minutes/60;
  minutes = (int) minutes%60;

  formattedTime = hours + ":" + minutes + ":" + seconds;
  return formattedTime;
}

Hope this helped!