Chapter 9, Problem 6E

Getting time from the user and set it to the variable “myTime” in the class “TimeOfDay.java” is as follows:

The statement to get and set the time using “try-catch” blocks in order to guarantee that “myTime” is valid or not is given below.

//Try block

try

{

    //Get the time from the user

    System.out.print("Enter the time (eg-1:11am): ");

    myTime = sc.next();

    //Call the function to set the time

    t.setTimeTo(time);

}

//Catch the exception

catch (InvalidFormattingException e)

{

    //Print the message

System.out.println("Found invalid format on time set: " +e.getMessage() );

}

//Catch the exception

catch (InvalidHourException e)

{

    //Print the message

System.out.println("Found invalid hour on time set: " +e.getMessage() );

}

//Catch the exception

catch (InvalidMinuteException e)

{

    //Print the message

System.out.println("Found invalid minute on time set: " +e.getMessage() );

}

Explanation:

In the above code segment:

• Inside “try” block,
  • The time will be entered by the user and it is set to the variable “myTime”.
  • Then the function “setTimeTo ()” is called in order to validate the time.
• The catch block catches “InvalidFormattingException”, “InvalidHourException” or “InvalidMinuteException” according to the thrown exception.

Class “TimeOfDay.java”:

/* In addition to TimeOfDat.java class; add InvalidFormattingException.java class, InvalidHourException.java class, and InvalidMinuteException.java class to the program*/

//Import required packages

import java.util.*;

import java.util.Scanner;

//Define the main class

class TimeOfDay

{

    //Declare required variables

    private int hour, minute;

    private boolean isAM;

    //Constructor

    public TimeOfDay()

    {

        //Instantiate the values

        hour = 0;

        minute = 0;

        isAM = false;

    }

    //Function definition to set the time

public void setTimeTo(String aTime) throws InvalidFormattingException, InvalidHourException, InvalidMinuteException

    {

        //Declare required variables

        int hourFound;

        int minuteFound;

        String indicatorFound;

        //Create an object for the scanner class

        Scanner reader = new Scanner(aTime);

        //Split using the delimiter

        reader.useDelimiter(":");

        //Try block

        try

        {

            //Assign the hour

            hourFound = reader.nextInt();

        }

        //Catch the exception

        catch (Exception e)

        {

            //Throw the exception with a message

throw new InvalidFormattingException("Hour not an integer");

        }

        //Check the condition

        if(hourFound<1 || hourFound>12)

            //Throw the exception with a message

throw new InvalidHourException("Hour not in the range of 1 to 12");

        //Get the remaining string

        String restOfString = reader.next();

        reader = new Scanner(restOfString);

        //Remove the last two characters

        if(restOfString.length()<3)

            //Throw the exception

throw new InvalidFormattingException("Bad format");

        //Get the substring

String minuteString = restOfString.substring(0, restOfString.length()-2);

        //Get the substring

String amString = restOfString.substring(restOfString.length()-2);

        //Try block

        try

        {

            //Convert the minute to integer

minuteFound = Integer.parseInt(minuteString);

        }

        //Catch the exception

        catch (Exception e)

        {

            //Throw the exception

throw new InvalidFormattingException("Minute not an integer");

        }

        //Check the condition

        if(minuteFound<0 || minuteFound>59)

            //Throw the exception with a message

throw new InvalidMinuteException("Minute not in the range of 0 to 59");

        //Check condition

if(!amString...