How to I validated an input for being an Int and within a number range?

Question

The program displays a question and the user is meant to input a number 1 to 5. 5 questions for 5 users. However, the program doesn't recognize a good input, or a bad, as long as its an Int. I have to enter input a bunch of times before it goes it runs Survey.presentQuestions() again. I can't figure out why.

    for (int i = 0; i < 5; i++) 
            {
                for (int j = 0; j < 5; j++) 
                {
                    Survey.presentQuestion(j, i);
                    do{
                        TempAns = in.nextInt();
                        while (!(in.hasNextInt()))
                        {
                            System.out.println("Please enter integer value from 1 to 5!");
                            in.next();
                        }
                    }while(TempAns >= 1 && TempAns <= 5);
                    Survey.ResultArray[i][j] = TempAns;

                }
            }

Are you sure this: while(TempAns >= 1 && TempAns <= 5); is correct? Shouldn't it be while(TempAns < 1 || TempAns > 5); — dragon66, Oct 06 '15 at 00:52
You might also need to move TempAns = in.nextInt(); under the inner while loop. — dragon66, Oct 06 '15 at 01:00

Isaac Schneider · Accepted Answer · 2015-10-06T03:52:20.120

1

Update try this instead

 for (int i = 0; i < 5; i++) {
    for (int i = 0; i < 5; i++) {
        for (int j = 0; j < 5; j++) {
            System.out.println("Student: "+(i+1)+" Grade: "+(j+1));
            System.out.println("Please enter integer value from 1 to 5!");
            TempAns = getNumber();
        }
    }

and this other method

 public int getNumber(){
    Scanner in =new Scanner(System.in);
    int validatedNumber;
    do{


    try{
        String toValidate=in.next();
        validatedNumber= Integer.parseInt(toValidate);
        if (validatedNumber>0 && validatedNumber<6){
            return validatedNumber;
        }else{
            System.out.println("Between 1 and 5!!");
        }
    }catch(Exception e){
        System.out.println("You have to chose a number!");
    }
    }while(true);

}

edited Oct 06 '15 at 03:52

answered Oct 06 '15 at 01:06

Isaac Schneider

172
4

actually thats not working. It crashes when i input a char. and when an int is out of my (1-5) range it keep going. – RIDDLEisVoltron Oct 06 '15 at 03:11
Perfect that works awesome. Thanks so much. Could you recommend a good tutorial on the try/catch syntax? Not real familiar with it at all. – RIDDLEisVoltron Oct 06 '15 at 15:38
@RIDDLEisVoltron sure, i think this one is good enough :) http://beginnersbook.com/2013/04/try-catch-in-java/ – Isaac Schneider Oct 06 '15 at 15:53

score 0 · Answer 2 · answered Oct 06 '15 at 01:05

I assume you want the user to enter an integer 1-5 and proceed to the next question? If so, try this:

Replace:

                    do{
                        TempAns = in.nextInt();
                        while (!(in.hasNextInt()))
                        {
                            System.out.println("Please enter integer value from 1 to 5!");
                            in.next();
                        }
                    }while(TempAns >= 1 && TempAns <= 5);

With:

while (true) {
            TempAns = in.nextInt();
            if (TempAns >= 1 && TempAns <= 5)
                return;
            else
                System.out.println("Please enter integer value from 1 to 5!");
        }

yeah when i input a string or char it crashes. – RIDDLEisVoltron Oct 06 '15 at 03:16 — RIDDLEisVoltron, Oct 06 '15 at 03:16

How to I validated an input for being an Int and within a number range?

2 Answers2