Question

public class Clock
{
  private int hr;
  private int min;
  private int sec;
  
  public Clock()
  {
    setTime(0, 0, 0);
  }
  
  public Clock(int hours, int minutes, int seconds)
  {
    setTime(hours, minutes, seconds);
  }
  
  public void setTime(int hours, int minutes, int seconds)
  {
    if (0 <= hours && hours < 24)
      hr = hours;
    else
      hr = 0;
    
    if (0 <= minutes && minutes < 60)
      min = minutes;
    else
      min = 0;
    
    if(0 <= seconds && seconds < 60)
      sec = seconds;
    else
      sec = 0;
  }
  
  public int getHours()
  {
    return hr;
  }
  
  public int getMinutes()
  {
    return min;
  }
  
  public int getSeconds()
  {
    return sec;
  }
  
  public void printTime()
  {
    if (hr < 10)
      System.out.print("0");
    System.out.print(hr + ":");
    
    if (min < 10)
      System.out.print("0");
    System.out.print(min + ":");
    
    if (sec < 10)
      System.out.print("0");
    System.out.print(sec);
  }
  
  public void incrementSeconds()
  {
    sec++;
    if (sec > 59)
    {
      sec = 0;
      incrementMinutes();
    }
  }
  
  public void incrementMinutes()
  {
    min++;
    if (min > 59)
    {
      min = 0;
      incrementHours();
    }
  }
  
  public void incrementHours()
  {
    hr++;
    if(hr > 23)
      hr = 0;
  }
  
  public boolean equals(Clock otherClock)
  {
    return (hr == otherClock.hr && min == otherClock.min && sec == otherClock.sec);
  }
  
  public void makeCopy(Clock otherClock)
  {
    hr =  otherClock.hr;
    min = otherClock.min;
    sec = otherClock.sec;
  }
  
  public Clock getCopy()
  {
    Clock temp = new Clock();
    
    temp.hr = hr;
    temp.min = min;
    temp.sec = sec;
    
    return temp;
  }
}

We learned the above class Clock, which was designed to implement the time of day in a program. Certain application in addition to hours, minutes, and seconds might require you to store the time zone. Please do the following:

1. Derive the class ExtClock from the class Clock by adding a data member to store the time zone. Add necessary methods and constructors to make the class functional. Also write the definitions of the methods and constructors.
2. Write a test program to test your new class.

Answer 1

This java code contains ExtClock class and it is tested in main function .

import java.util.Calendar;
import java.util.TimeZone;
class Clock
{
private int hr;
private int min;
private int sec;
  
public Clock()
{
setTime(0, 0, 0);
}
  
public Clock(int hours, int minutes, int seconds)
{
setTime(hours, minutes, seconds);
}
  
public void setTime(int hours, int minutes, int seconds)
{
if (0 <= hours && hours < 24)
hr = hours;
else
hr = 0;
  
if (0 <= minutes && minutes < 60)
min = minutes;
else
min = 0;
  
if(0 <= seconds && seconds < 60)
sec = seconds;
else
sec = 0;
}
  
public int getHours()
{
return hr;
}
  
public int getMinutes()
{
return min;
}
  
public int getSeconds()
{
return sec;
}
  
public void printTime()
{
if (hr < 10)
System.out.print("0");
System.out.print(hr + ":");
  
if (min < 10)
System.out.print("0");
System.out.print(min + ":");
  
if (sec < 10)
System.out.print("0");
System.out.print(sec);
}
  
public void incrementSeconds()
{
sec++;
if (sec > 59)
{
sec = 0;
incrementMinutes();
}
}
  
public void incrementMinutes()
{
min++;
if (min > 59)
{
min = 0;
incrementHours();
}
}
  
public void incrementHours()
{
hr++;
if(hr > 23)
hr = 0;
}
  
public boolean equals(Clock otherClock)
{
return (hr == otherClock.hr && min == otherClock.min && sec == otherClock.sec);
}
  
public void makeCopy(Clock otherClock)
{
hr = otherClock.hr;
min = otherClock.min;
sec = otherClock.sec;
}
  
public Clock getCopy()
{
Clock temp = new Clock();
  
temp.hr = hr;
temp.min = min;
temp.sec = sec;
  
return temp;
}

}
/* creation of new class ExtClock that is derived from class Clock */
class ExtClock extends Clock
{
public String Tzone; //data member to store the timezone
public void getTzone() //method which displays the current timezone
{
Calendar n = Calendar.getInstance(); //this is to get calendar instance
/* java Calendar class and Timezone class are imported at the top of the code */
/* getTimeZone method of Calendar class is used to retrieve current timezone */
TimeZone tzone = n.getTimeZone();
Tzone=tzone.getDisplayName(); /*to store the timezone to Tzone variable using getDisplayName method of TimeZone class */
System.out.println("current timezone is : " +Tzone );
  
}
}
public class Main{
public static void main(String[] args) {
ExtClock c = new ExtClock();
c.getTzone(); //This displays the time zone
}
}

//This code will give the correct output

Output

current timezone is : Coordinated Universal Time

NB

Test program is also included with that code.Its is tested successfully and out put is obtained.

if test program needed , then here it is

(before that make changes to the java code by making the classes Clock and ExtClock to a package named Pclock by simply writing "package Pclock; " at top of the code ie top of importing calendar class and save it with file name of that class . Remove void main code from that package)

program to test the ExtClock class

import Pclock.*; //to import the Pclock package

public class Main{
public static void main(String[] args) {
ExtClock c = new ExtClock();
c.getTzone(); //This displays the time zone
}
}