Question

Here is the code of TimeSpan.java

// Represents a time span of hours and minutes elapsed.
// Alternate implementation using only total minutes.

public class 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 whether o is a TimeSpan representing the same
// number of hours and minutes as this TimeSpan object.
public boolean equals(Object o) {
if (o instanceof TimeSpan) {
TimeSpan other = (TimeSpan) o;
return totalMinutes == other.totalMinutes;
} else { // not a TimeSpan object
return false;
}
}

// Returns a String for this time span such as "6h15m".
public String toString() {
return (totalMinutes / 60) + "h" +
(totalMinutes % 60) + "m";
}
}

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The Question is:

Add the following mutator method to the TimeSpan class:

public void add(TimeSpan span)

Adds the given amount of time to this time span.

Answer 1

// Represents a time span of hours and minutes elapsed.
// Alternate implementation using only total minutes.
public class 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 whether o is a TimeSpan representing the same
    // number of hours and minutes as this TimeSpan object.
    public boolean equals(Object o) {
        if (o instanceof TimeSpan) {
            TimeSpan other = (TimeSpan) o;
            return totalMinutes == other.totalMinutes;
        } else { // not a TimeSpan object
            return false;
        }
    }

    // Returns a String for this time span such as "6h15m".
    public String toString() {
        return (totalMinutes / 60) + "h" + (totalMinutes % 60) + "m";
    }

    // Adds the given amount of time to this time span.
    public void add(TimeSpan span) {
        // add totalMinutes of span to the current object
        totalMinutes += span.totalMinutes;
    }
}