CODEWITHSUNDEEP
java
Singh
Singh

Reputation: 301

Java: Easier Way to Re-prompt user for input when invalid data is entered

I am creating a simple program using the java language which uses a bunch of similar methods to retrieve information from the user. The method i have used to deal with the user entering invalid data seems very incorrect to me, so i am seeking professional guidance on how to better handle invalid data.

I have attempted to search for similar questions but have found none.

This is a sample of one of my methods:

public static int getInput()
{
    int temp = 1;

    do
    {
        System.out.println("Answers must be between 1 and 15");
        temp =  reader.nextInt();

        if(temp >=1 && temp <= 15)
        {
            return temp;
        }
        else
        {
            System.out.println("Please enter a valid value");
        }
    }while(temp > 15 || temp < 1);

    //This value will never be reached because the do while loop structure will not end until a valid return value is determined
    return 1;
}//End of getInput method

Is there a better way to write this method?

This question is entirely made up so i can learn a better method to implement in my future programs.

Is using a labeled break statement acceptable? such as:

public static int getInput()
{
    int temp = 1;

    start:

        System.out.println("Answers must be between 1 and 15");
        temp =  reader.nextInt();

        if(temp >=1 && temp <= 15)
        {
            return temp;
        }
        else
        {
            System.out.println("Please enter a valid value");
            break start;
        }


}

Thank you very much in advance.

Upvotes: 2

Views: 11975

Answers (2)

qqilihq
qqilihq

Reputation: 11474

You have forgotten to check the case, that non-number values are entered (Scanner#nextInt throws a java.util.InputMismatchException). One suggestion which takes care of that issue, is less redundant and more flexible:

public static int getInput(int min, int max) {
    for (;;) {
        Scanner scanner = new Scanner(System.in);
        System.out.println(String.format("Answers must be between %s and %s", min, max));
        try {
            int value = scanner.nextInt();
            if (min <= value && value <= max) {
                return value;
            } else {
                System.out.println("Please enter a valid value");
            }
        } catch (InputMismatchException e) {
            System.out.println("Input was no number");
        }
    }
}

Upvotes: 2

Dan675
Dan675

Reputation: 1767

If you are just worried about the return that is not used and double checking temp you can do something like

public static int getInput()
{
    while(true)
    {
        System.out.println("Answers must be between 1 and 15");
        temp = reader.nextInt();

        if(temp >=1 && temp <= 15)
        {
            return temp;
        }
        else
        {
            System.out.println("Please enter a valid value");
        }
    }
}//End of getInput method

Upvotes: 0

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