Question

Assignment 4 - Time Comparable

For this assignment, you will be updating the Time class from Assignment 1. To get started, you can either make a copy of your Assignment 1 Time.java, or download the solution, Time.java.

This is Assignment 1:

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public class Time {

private int h;

private int m;

public Time() {

super();

}

public Time(int h, int m){

if(h>=1 && h<=23){

this.h = h;

}else{

this.h = 0;

}

if(m>=0 && m<=59){

this.m = m;

}else{

this.m = 0;

}

}

public int getH() {

return h;

}

public void setH(int h) {

this.h = h;

}

public int getM() {

return m;

}

public void setM(int m) {

this.m = m;

}

public String convert(){

String standardTime = "";

String flag = "";

if(h>= 0 && h < 12){

flag = " AM";

if(h == 0){

standardTime = Integer.toString(12);

}

else{

standardTime = Integer.toString(h);

}

}else{

flag = " PM";

if(h == 12){

standardTime = Integer.toString(12);

}

else{

standardTime = Integer.toString(h - 12);

}   

}

standardTime += ":";

standardTime += Integer.toString(m).toCharArray().length == 1 ? "0"+Integer.toString(m):Integer.toString(m);

standardTime += flag;

return standardTime;

}

public void increment() {

int min = this.m;

min++;

if(min == 60){

this.m = 00;

this.h++;

if(this.h == 24){

this.h = 0;

}

}else{

this.m = min;

}

}

public String toString() {

String hour = Integer.toString(h).toCharArray().length == 1 ? "0" + Integer.toString(h) : Integer.toString(h);

String minutes = Integer.toString(m).toCharArray().length == 1 ? "0" + Integer.toString(m) : Integer.toString(m);

return hour + minutes ;

}

}

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First, you will need to update Time so that it implements the Comparable interface. This will require adding an implements statement to the class declaration as well as the compareTo method. Then, you will need to add a difference method to the class. These two methods' requirements are as follows:

compareTo(Object other)
    //Returns -1 if current time is less than other.
    //Returns 0 if current time is equal to other.
    //Returns 1 if current time is greater than other.

String difference(Time t)
    //Returns a String holding the difference between the current time and
    //the Time t passed in via parameter. All values should be positive,
    //and in the format:
    //Time difference: 08:09
    //Time difference: 10:35

To test your code, download and run the runner class: student_runner_time.java. We will use a different, but similar, test class to grade the program. You will need to change the runner to test with other values to make sure your program fits all the requirements.

Sample Run of student_runner_time.java:

1712
0945
Greater than:
1
Less than:
-1
Times equal:
0
Hours equal:
1
-1
Difference
Time difference: 00:11
Time difference: 00:11
Time difference: 00:00

NOTE: You MUST use the class name "Time" for this assignment. REMEMBER: you must SUBMIT your answer. Your assignment doesn't count as complete unless it has been submitted.

Answer 1

Thanks for the question, here are the implementation of the compareTo() and difference() methods. It would have been good if you could have shared the  student_runner_time.java file so that I could have tested the code.

Nevertheless, please run the test code and if any changes is needed please do comment.

thank you

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public class Time implements Comparable {

    private int h;
    private int m;

    public Time() {
        super();
    }

    public Time(int h, int m) {
        if (h >= 1 && h <= 23) {
            this.h = h;
        } else {
            this.h = 0;
        }
        if (m >= 0 && m <= 59) {
            this.m = m;
        } else {
            this.m = 0;
        }
    }

    public int getH() {
        return h;
    }

    public void setH(int h) {
        this.h = h;
    }

    public int getM() {
        return m;
    }

    public void setM(int m) {
        this.m = m;
    }

    public String convert() {
        String standardTime = "";
        String flag = "";
        if (h >= 0 && h < 12) {
            flag = " AM";
            if (h == 0) {
                standardTime = Integer.toString(12);
            } else {
                standardTime = Integer.toString(h);
            }
        } else {
            flag = " PM";
            if (h == 12) {
                standardTime = Integer.toString(12);
            } else {
                standardTime = Integer.toString(h - 12);
            }
        }
        standardTime += ":";
        standardTime += Integer.toString(m).toCharArray().length == 1 ? "0" + Integer.toString(m) : Integer.toString(m);
        standardTime += flag;
        return standardTime;
    }

    public void increment() {
        int min = this.m;
        min++;
        if (min == 60) {
            this.m = 00;
           this.h++;
            if (this.h == 24) {
                this.h = 0;
            }
        } else {
            this.m = min;
        }
    }

    public String toString() {
        String hour = Integer.toString(h).toCharArray().length == 1 ? "0" + Integer.toString(h) : Integer.toString(h);
        String minutes = Integer.toString(m).toCharArray().length == 1 ? "0" + Integer.toString(m) : Integer.toString(m);
        return hour + minutes;
    }

    @Override
    public int compareTo(Object time) {
        if (time == null || !(time instanceof Time)) return -1;
        Time aTime = (Time) time;

        int result = (h * 60 + m) - (aTime.getH() * 60 + aTime.getM());
        if(result>0) return 1;
        else if(result<0) return -1;
        else return 0;
    }

    public String difference(Time t){
           
        int currentTimeTotalMins = h*60 + m;
        int passedTimeTotalMins = t.getH()*60 + t.getM();
       
        int differenceMins = Math.abs(currentTimeTotalMins-passedTimeTotalMins);
      int hrs = differenceMins/60;
        int mins = differenceMins%60;
       
        return new Time(hrs,mins).toString();
       
    }
}

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