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Saturday, 10 September 2016

Chapter 10 Exercise 1, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

10.1 (The Time class) Design a class named Time. The class contains:

■ The data fields hour, minute, and second that represent a time.
■ A no-arg constructor that creates a Time object for the current time.
    (The values of the data fields will represent the current time.)
■ A constructor that constructs a Time object with a specified elapsed time since midnight,
    January 1, 1970, in milliseconds. (The values of the data fields will represent this time.)
■ A constructor that constructs a Time object with the specified hour, minute, and second.
■ Three getter methods for the data fields hour, minute, and second, respectively.
■ A method named setTime(long elapseTime) that sets a new time for the object using the
    elapsed time. For example, if the elapsed time is 555550000 milliseconds,
    the hour is 10, the minute is 19, and the second is 10.

Draw the UML diagram for the class and then implement the class.
Write a test program that creates two Time objects (using new Time() and new Time(555550000))
and displays their hour, minute, and second in the format hour:minute:second.
(Hint: The first two constructors will extract the hour, minute, and second from the elapsed time.
For the no-arg constructor, the current time can be obtained using System.currentTimeMillis(),
as shown in Listing 2.7, ShowCurrentTime.java.)


public class Time {

    public long hour;
    public long minute;
    public long second;

    public Time() {
        long totalSeconds = System.currentTimeMillis() / 1000;
        long totalMinutes = totalSeconds / 60;
        long totalHours = totalMinutes / 60;
        this.hour = totalHours % 24;
        this.minute = totalMinutes % 60;
        this.second = totalSeconds % 60;

    }

    public Time(long hour, long minute, long second) {
        this.hour = hour;
        this.minute = minute;
        this.second = second;
    }

    public Time(long elapseTime) {
        long totalSeconds = elapseTime / 1000;
        long totalMinutes = totalSeconds / 60;
        long totalHours = totalMinutes / 60;
        this.hour = totalHours % 24;
        this.minute = totalMinutes % 60;
        this.second = totalSeconds % 60;

    }

    public long getHour() {
        return hour;
    }


    public long getMinute() {
        return minute;
    }


    public long getSecond() {
        return second;
    }



}
public class Exercise_01 {

    public static void main(String[] args) {


        Time time = new Time(555550000);
        System.out.println(time.hour + ":" + time.minute + ":" + time.second);

    }


}

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