Branching and looping in Java (break and continue)

Question

Hi I am trying to write a code that gives an output similar to

Enter time in 24-hour notation:
13:07
That is the same as
1:07 PM
Again? (y/n)
y
 
Enter time in 24-hour notation:
10:15
That is the same as
10:15 AM
Again? (y/n)
y
 
Enter time in 24-hour notation:
10:65
There is no such time as 10:65
Try Again:
Enter time in 24-hour notation:
16:05
That is the same as
4:05 PM
Again? (y/n)
n
End of program

But I have ended up making a few errors and I am unable to figure it out.

public class prp {
    public static void main(String[] args) {
        while (true) //add the remaining logic
        {
            System.out.println("Enter time in 24-hour notation HH:MM");
            Scanner x = new Scanner(System.in);
            String newhr = x.nextLine();
            String hr[] = newhr.split(":");
            int hours = Integer.parseInt(hr[0]);//HH
            int minutes = Integer.parseInt(hr[1]);//MM

            if ((hours >= 00 && hours <= 24) && (minutes >= 00 && minutes <= 59)) {
                System.out.println("That is the same as: ");
                if (hours <= 12) {
                    System.out.println(hours + ":" + minutes + " AM");
                    //System.exit(0);
                } else if (hours > 12 && hours < 24) {
                    int hoursnew = hours - 12;
                    System.out.println(hoursnew + ":" + minutes + " PM");
                    //System.exit(0);
                }
            } else {
                System.out.println("There is no such time as " + hours + " : " + minutes);
                System.out.println("Try Again!");
                //continue;
            }
            System.out.println("Again? [y/n]");
            Scanner y = new Scanner(System.in);
            String newyn = y.nextLine();
            if (newyn == "y" || newyn == "n") {
                if (newyn == "y") {
                    continue;
                } else {
                    System.out.println("End of program");
                    System.exit(0);
                    //break;
                }
            }//end of while
        }
    }
}

The program displays error while inputting non-integers. Furthermore it is not breaking. I am suppose to create another exception class called TimeFormatException If the user enters an illegal time, like 10:65, or like ab:cd.

http://stackoverflow.com/questions/2912817/how-to-use-scanner-to-accept-only-valid-int-as-input check this link for take only int as input. — Shiladittya Chakraborty, Oct 10 '15 at 19:35

rupesh_padhye · Answer 1 · 2015-10-10T18:42:02.693

There are two mistake in program .

1.Before parsing into integer validate user input is valid number or not use regex. If matches returns false throw exception.

String s="235:23";//user input
System.out.println(s.matches("\\d{0,2}:\\d{0,2}"));

2.Instead of equalsIgnoreCase or equals, you are using == to compare strings

 if( "y".equalsIgnoreCase(newyn) || "n".equalsIgnoreCase(newyn))

please,follow some coding standards!

score 0 · Accepted Answer · edited Mar 22 '18 at 08:19

Actually in your code you are not comparing string properly as well as you are not handling your code if user enter other than a Y/N on asking and a wrong input on time. See below code:

import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.Scanner;

public class Exam {
    public static void main(String[] args) {
        while (true) // add the remaining logic
        {
            System.out.println("Enter time in 24-hour notation HH:MM");
            Scanner x = new Scanner(System.in);
            String newhr = x.nextLine();
            String hr[] = newhr.split(":");
            int hours = 0;
            int minutes = 0;
            try {
                hours = Integer.parseInt(hr[0]);// HH
                minutes = Integer.parseInt(hr[1]);// MM
            } catch (NumberFormatException e) {
                System.out.println("Wrong time input");
                continue;
            }
            if ((hours >= 00 && hours <= 24)
                    && (minutes >= 00 && minutes <= 59)) {
                System.out.println("That is the same as: ");
                if (hours <= 12) {
                    System.out.println(hours + ":" + minutes + " AM");
                    // System.exit(0);
                } else if (hours > 12 && hours < 24) {
                    int hoursnew = hours - 12;
                    System.out.println(hoursnew + ":" + minutes + " PM");
                    // System.exit(0);
                }
            } else {
                System.out.println("There is no such time as " + hours + " : "
                        + minutes);
                System.out.println("Try Again!");
                // continue;
            }

            while (true) {
                System.out.println("Again? [y/n]");
                Scanner y = new Scanner(System.in);
                String newyn = y.nextLine();
                if ("y".equalsIgnoreCase(newyn)) {
                    break;
                } else if ("n".equalsIgnoreCase(newyn)) {
                    System.out.println("End of program");
                    System.exit(0);
                    // break;
                } else {
                    System.out.println("Enter correct input Y or N");
                }
            }
            // end of while
        }
    }
}

Branching and looping in Java (break and continue)

2 Answers2