Question

//Time24.java

import java.util.StringTokenizer;

import java.text.DecimalFormat;

/**

A data structure that stores integer values for hour (0..23) and minute (0..59) to represent the time of day in a 24-hour clock

*/

public class Time24

{

private int hour;

private int minute;

//Post: Sets the hour value in the range 0 to 23 and the minute value in the range 0 to 59

    private void normalizeTime()

    {

       int extraHours = minute / 60;

       minute %= 60;

       hour = (hour + extraHours) % 24;

    }

/**

Desc:Initializes this Time24 object

Post:hour and minute of this Time24 object both initialized to 0

*/

public Time24()

     {

         this(0,0); //calls the 2-argument constructor of class Time24

     }

/**

Desc:Initializes this Time24 object

Pre:h and m cannot be negative

Post:hour and minute of this Time24 object initialized to h and m

respectively. This operation will normalize the time if necessary (e.g.

9:75 is stored as 10:15).

Throw:IllegalArgumentException if h or m is negative

*/

public Time24(int h, int m)

    {

       setTime(h, m);

   }

/**

Desc:Sets the hour and minute of this Time24 object to a particular time

Pre:h and m cannot be negative

Post:hour and minute of this Time24 object set to h and m

respectively. This operation will normalize the time if necessary (e.g.

9:75 is stored as 10:15).

Throw:IllegalArgumentException if h or m is negative

*/

public void setTime(int h, int m)

    {

if (h < 0 || m < 0)

          throw new IllegalArgumentException("Time24.setTime: argument"

+ " must not be negative");

       this.hour = h;

      this.minute = m;

normalizeTime();

    }

/**

Desc:Adds minutes to this Time24 object

Pre:m cannot be negative

Post:This Time24 object set to m minutes later. This operation will

normalize the time if necessary (e.g. 9:75 is stored as 10:15).

Throw:IllegalArgumentException if m is negative

*/

public void addTime(int m)

    {

       if (m < 0)

          throw new IllegalArgumentException("Time24.addTime: argument"

+ " must not be negative");

       minute += m;

       normalizeTime();

    }

/**

Desc:Measures the interval from this Time24 object to another time

Return:The interval from this Time24 object to t as a Time24

*/

public Time24 interval(Time24 t)

    {

int currTime = hour * 60 + minute;

       int tTime = t.hour * 60 + t.minute;

if (tTime < currTime) tTime += 24 * 60;

return new Time24(0, tTime-currTime);

    }

/**

Desc:Gets the hour value of this Time24 object

Return:The hour value of this Time24 object

*/

public int getHour()

    {

return hour;

}

/**

Desc:Gets the minute value of this Time24 object

Return:The minute value of this Time24 object

*/

public int getMinute()

    {

return minute;

}

/**

Desc:Converts this Time24 object to a string

Return:This Time24 object as a String in the form "hh:mm"

*/

public String toString()

    {

DecimalFormat f = new DecimalFormat("00");

return hour + ":" + f.format(minute);

    }

/**

Desc:Convert a String to a Time24

Pre:s must be in the form "hh:mm" where hh and mm are positive integers

Return:A Time24 object that corresponds to s

*/

public static Time24 parseTime(String s)

    {

StringTokenizer t = new StringTokenizer(s, ":");

int h = Integer.parseInt(t.nextToken());

int m = Integer.parseInt(t.nextToken());

return new Time24(h, m);

}

}

Add 1 method, readTime, to class Time24.

Usage: void readTime(Scanner f)

Desc: Read from f the hour and minute for this Time24 object

Pre: f is ready to be read, and the next line contains hh:mm where hh:mm gives a valid 24-

hour time

Post: The entire line hh:mm read in from f.

The hour and minute of this Time24 object set to hh and mm respectively.  

The operation will normalize the time if necessary (e.g. 9:75 is stored as 10:15).

Answer 1

import java.util.Scanner;
import java.util.StringTokenizer;
import java.text.DecimalFormat;

/**
A data structure that stores integer values for hour (0..23) and minute (0..59) to represent the time of day in a 24-hour clock
*/

public class Time24 {

   private int hour;
   private int minute;

   //Post: Sets the hour value in the range 0 to 23 and the minute value in the range 0 to 59
   private void normalizeTime()
   {
       int extraHours = minute / 60;
       minute %= 60;
       hour = (hour + extraHours) % 24;
   }
  
   /**
   Desc:Initializes this Time24 object
   Post:hour and minute of this Time24 object both initialized to 0
   */
   public Time24()
   {
       this(0,0); //calls the 2-argument constructor of class Time24
   }
  
   /**
   Desc:Initializes this Time24 object
   Pre:h and m cannot be negative
   Post:hour and minute of this Time24 object initialized to h and m
   respectively. This operation will normalize the time if necessary (e.g.
   9:75 is stored as 10:15).
   Throw:IllegalArgumentException if h or m is negative
   */

   public Time24(int h, int m)
   {
       setTime(h, m);
   }
  
   /**
   Desc:Sets the hour and minute of this Time24 object to a particular time
   Pre:h and m cannot be negative
   Post:hour and minute of this Time24 object set to h and m
   respectively. This operation will normalize the time if necessary (e.g.
   9:75 is stored as 10:15).
   Throw:IllegalArgumentException if h or m is negative
   */
   public void setTime(int h, int m)
   {

       if (h < 0 || m < 0)
           throw new IllegalArgumentException("Time24.setTime: argument"
                   + " must not be negative");
       this.hour = h;
       this.minute = m;
       normalizeTime();
   }
  
   /**
   Desc:Adds minutes to this Time24 object
   Pre:m cannot be negative
   Post:This Time24 object set to m minutes later. This operation will
   normalize the time if necessary (e.g. 9:75 is stored as 10:15).
   Throw:IllegalArgumentException if m is negative
   */
   public void addTime(int m)
   {
       if (m < 0)
           throw new IllegalArgumentException("Time24.addTime: argument"
                   + " must not be negative");
       minute += m;
       normalizeTime();
   }
  
   /**
   Desc:Measures the interval from this Time24 object to another time
   Return:The interval from this Time24 object to t as a Time24
   */
   public Time24 interval(Time24 t)
   {
       int currTime = hour * 60 + minute;
       int tTime = t.hour * 60 + t.minute;
       if (tTime < currTime)
           tTime += 24 * 60;
       return new Time24(0, tTime-currTime);
   }
  
   /**
   Desc:Gets the hour value of this Time24 object
   Return:The hour value of this Time24 object
   */
   public int getHour()
   {
       return hour;
   }
  
   /**
   Desc:Gets the minute value of this Time24 object
   Return:The minute value of this Time24 object
   */
   public int getMinute()
   {
       return minute;
   }

   /**
   Desc:Converts this Time24 object to a string
   Return:This Time24 object as a String in the form "hh:mm"
   */
   public String toString()
   {
       DecimalFormat f = new DecimalFormat("00");
       return hour + ":" + f.format(minute);
   }
  
   /**
   Desc:Convert a String to a Time24
   Pre:s must be in the form "hh:mm" where hh and mm are positive integers
   Return:A Time24 object that corresponds to s
   */
   public static Time24 parseTime(String s)
   {
       StringTokenizer t = new StringTokenizer(s, ":");
       int h = Integer.parseInt(t.nextToken());
       int m = Integer.parseInt(t.nextToken());
       return new Time24(h, m);
   }
  
   /**
   * Desc: Read from f the hour and minute for this Time24 object
   * Pre: f is ready to be read, and the next line contains hh:mm where hh:mm gives a valid 24-hour time
   * Post: The entire line hh:mm read in from f.
   * The hour and minute of this Time24 object set to hh and mm respectively.
   * The operation will normalize the time if necessary (e.g. 9:75 is stored as 10:15).
   */
   public void readTime(Scanner f)
   {
       // read the entire line from f and set it to line
       String line = f.nextLine();
       Time24 obj = parseTime(line); // parse the line using the method parseTime and set the resultant object to obj
       // update hour and minute to obj's hour and minute
       this.hour = obj.hour;
       this.minute = obj.minute;
   }
  
}