Question

Modify the TimeSpan class from Chapter 8 to include a compareTo method that compares time spans by their length. A time span that represents a shorter amount of time is considered to be "less than" one that represents a longer amount of time. For example, a span of 3 hours and 15 minutes is greater than a span of 1 hour and 40 minutes.GIVEN TIMESPAN FILE/** Adapted for CS211 from Building Java Programs, 4th Edition,* by Stuart Reges and Marty Stepp* adapted by James Livingston, Bellevue College Adjunct Instructor*/// Represents a time span of elapsed hours and minutes.// Simple implementation using only total minutes as state.public class TimeSpan {private int totalMinutes;// Constructs a time span with the given interval.// pre: hours >= 0 && minutes >= 0public TimeSpan(int hours, int minutes) {totalMinutes = 0;add(hours, minutes);}// Adds the given interval to this time span.// pre: hours >= 0 && minutes >= 0public void add(int hours, int minutes) {totalMinutes += 60 * hours + minutes;}// Returns a String for this time span such as "6h15m".public String toString() {return (totalMinutes / 60) + "h"+ (totalMinutes % 60) + "m";}}GIVEN TIMESPANMAIN FILE/** TimeSpanClient: a simple test client for the TimeSpan class* Shows creation of an instance object, displaying that object,* adding hours and minutes to that object, and showing the result.*/public class TimeSpanClient {public static void main(String[] args) {int h1 = 13, m1 = 30;TimeSpan t1 = new TimeSpan(h1, m1);System.out.println("New object t1: " + t1); h1 = 3; m1 = 40;System.out.println("Adding " + h1 + " hours, " + m1 + " minutes to t1");t1.add(h1, m1);System.out.println("New t1 state: " + t1);}}

Answer 1

Answer:

Check the explanation

Explanation:

Here is the modified code for

TimeSpan.java and TimeSpanClient.java.

// TimeSpan.java

//implemented Comparable interface, which has the compareTo method

//and can be used to sort a list or array of TimeSpan objects without

//using a Comparator

public class TimeSpan implements Comparable<TimeSpan> {

   private int totalMinutes;

   // Constructs a time span with the given interval.

   // pre: hours >= 0 && minutes >= 0

   public TimeSpan(int hours, int minutes) {

        totalMinutes = 0;

        add(hours, minutes);

   }

   // Adds the given interval to this time span.

   // pre: hours >= 0 && minutes >= 0

   public void add(int hours, int minutes) {

        totalMinutes += 60 * hours + minutes;

   }

   // Returns a String for this time span such as "6h15m".

   public String toString() {

        return (totalMinutes / 60) + "h" + (totalMinutes % 60) + "m";

   }

   // method to compare this time span with other

   // returns a negative value if this time span is shorter than other

   // returns 0 if both have same duration

   // returns a positive value if this time span is longer than other

   public int compareTo(TimeSpan other) {

        if (this.totalMinutes < other.totalMinutes) {

            return -1; // this < other

        } else if (this.totalMinutes > other.totalMinutes) {

            return 1; // this > other

        } else {

            return 0; // this = other

        }

   }

}

// TimeSpanClient.java

public class TimeSpanClient {

   public static void main(String[] args) {

        int h1 = 13, m1 = 30;

        TimeSpan t1 = new TimeSpan(h1, m1);

        System.out.println("New object t1: " + t1);

        h1 = 3;

        m1 = 40;

        System.out.println("Adding " + h1 + " hours, " + m1 + " minutes to t1");

        t1.add(h1, m1);

        System.out.println("New t1 state: " + t1);

        // creating another TimeSpan object, testing compareTo method using the

        // two objects

        TimeSpan t2 = new TimeSpan(10, 20);

        System.out.println("New object t2: " + t2);

        System.out.println("t1.compareTo(t2): " + t1.compareTo(t2));

        System.out.println("t2.compareTo(t1): " + t2.compareTo(t1));

        System.out.println("t1.compareTo(t1): " + t1.compareTo(t1));

   }

}

/*OUTPUT*/

New object t1: 13h30m

Adding 3 hours, 40 minutes to t1

New t1 state: 17h10m

New object t2: 10h20m

t1.compareTo(t2): 1

t2.compareTo(t1): -1

t1.compareTo(t1): 0