CODEWITHSUNDEEP
java
Joey Deguzman
Joey Deguzman

Reputation: 113

How would I convert this to a for loop?

The user would need to enter a number for the meter reading, a try catch block will initialize if the user enters anything other than a number and an error message pops out if the user has a negative number, doing this in do-while would be simple but I am stumped on how this would be a for-loop 

    public static int readStartReading(){ 
    int reading = 0;
    Scanner keyboard = new Scanner(System.in);
    boolean problemFlag = false;
    do {
        problemFlag = false;
        try {
            System.out.print("Enter the meter reading at the beginning of the year: ");
            String input = keyboard.nextLine();
            reading = Integer.parseInt(input);// 7. Assign a value to reading through the input device
        } catch (NumberFormatException x){
            problemFlag = true;
            System.out.println("You have to enter a number.");
        } if (reading < 0){
            System.out.println("The beginning meter reading cannot be negative."); }
    } while (reading < 0 || problemFlag);
    return reading;
}

I have noticed my mistake. Thank you for the responses

Upvotes: 0

Views: 98

Answers (2)

Thallius
Thallius

Reputation: 2619

What about

public static int readStartReading()
{ 
int reading = -1; 
Scanner keyboard; //remove first reading here

while(1)
{
    try 
    {
        System.out.print("Enter the meter reading at the beginning of the year: ");
        String input = keyboard.nextLine();
        reading = Integer.parseInt(input);// 7. Assign a value to reading through the input device

        //if control reaches here, you have a valid integer, test it
        if (reading >= 0)
            break;
        else
            System.out.println("The beginning meter reading cannot be negative.");
    } 
    catch (NumberFormatException x)
        System.out.println("You have to enter a number.");
} 
return reading;

}

Upvotes: 2

Andrei Diea
Andrei Diea

Reputation: 56

You can convert it to a for loop very simply but it will not be any difference. In your case a do-while is better suited.

public static int readStartReading(){ 
int reading = 0;
Scanner keyboard = new Scanner(System.in);
boolean problemFlag = false;
for(;reading < 0 || problemFlag;)
{
    problemFlag = false;
    try {
        System.out.print("Enter the meter reading at the beginning of the year: ");
        String input = keyboard.nextLine();
        reading = Integer.parseInt(input);// 7. Assign a value to reading through the input device
    } catch (NumberFormatException x){
        problemFlag = true;
        System.out.println("You have to enter a number.");
    } if (reading < 0){
        System.out.println("The beginning meter reading cannot be negative."); }
}
return reading;
}

There are also couple small issues

  • you don't need the problemFlag

  • you are doing the initial reading twice, (user will have to input value twice)

I would rewrite it like so:

public static int readStartReading()
{ 
int reading = 0;
Scanner keyboard; //remove first reading here

do
{
    try {
        System.out.print("Enter the meter reading at the beginning of the year: ");
        String input = keyboard.nextLine();
        reading = Integer.parseInt(input);// 7. Assign a value to reading through the input device

        //if control reaches here, you have a valid integer, test it
        if (reading < 0)
            System.out.println("The beginning meter reading cannot be negative.");

    } catch (NumberFormatException x){
        reading = -1; //set reading to a negative invalid value
        System.out.println("You have to enter a number.");
    }
} while(reading < 0)
return reading;
}

Upvotes: 1

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