CODEWITHSUNDEEP
javaif-statementreturn
user10924919
user10924919

Reputation:

How to write a program which can continuously ask users for inputs until the inputs meet a specific requirement to run the code?

I have to write a program that starts by requesting an integer in the range 0 < N < 20. Numbers outside this range are rejected and a new request is made. Output the sum of the sequence of numbers starting at 1 and ending with N. I have got most of the codes but I can not continuously ask users for inputs until an input meets the requirement. I tried to use "return" in line 11, however, it does not go back into the loop after getting another input. What should I do now?

import java.util.*;
class ExamTesterNine{
  public static void main(String args[]){
   Scanner kbReader= new Scanner(System.in);
   int num=kbReader.nextInt();
   System.out.println("Enter an integer smaller than 20 and larger than 0");
   int result;
   int sum=0;

   if (!(num>0&&num<20)){
     return;
   }else{
     for(int i=1; i<=num; i++)
   sum=sum+i;

   int [] number= new int [num];
   for (int a=0; a<(number.length-1); a++ ){
     number[a]=a+1;
     System.out.print(number[a]+"+");}
   System.out.print(num+"="+sum);
   }

  }
}

Upvotes: 0

Views: 905

Answers (5)

Avvappa Hegadyal
Avvappa Hegadyal

Reputation: 273

import java.util.*;
class ExamTesterNine{
static int num;
public static void readInput() {
     System.out.println("Enter an integer smaller than 20 and larger than 0");
       Scanner kbReader= new Scanner(System.in);
       num=kbReader.nextInt();
       if (!(num>0&&num<20)){
           ExamTesterNine.readInput();
       }else {
           calculate(num); 
       }
   }
public static void calculate(int sum) {
    for(int i=1; i<=num; i++)
           sum=sum+i;
           int [] number= new int [num];
           for (int a=0; a<(number.length-1); a++ ){
             number[a]=a+1;
             System.out.print(number[a]+"+");}
           System.out.print(num+"="+sum);
}

  public static void main(String args[]){
  int result;
  int sum=0;
  ExamTesterNine.readInput();
    }
 }

 Are you expecting this?
  Out put:Enter an integer smaller than 20 and larger than 0
  23
  Enter an integer smaller than 20 and larger than 0
  34
  Enter an integer smaller than 20 and larger than 0
  56
  Enter an integer smaller than 20 and larger than 0
  45
  Enter an integer smaller than 20 and larger than 0
  15
  1+2+3+4+5+6+7+8+9+10+11+12+13+14+15=135

Upvotes: 0

some IT dood
some IT dood

Reputation: 78

To get a number, try using a check like this

int number=0;
boolean flag;
while{
    flag=false;
    System.out.println("Enter a number smaller than 20 and greater than 0 : ");
    try{          
        number=kbReader.nextInt();
        flag=true;
    }catch(Exception e){ //catching the exception that occurs when an input other than integer is entered
        System.out.println("OOPS!!!only Integer is allowed :-("); 
    }
    if(flag==true && number>0 && number<20){
        break;
    }else{
        if(flag){
        System.out.println("Oops!!!only numbers in the range 0<number<20 is allowed...Re-enter again");
        }
    }

Upvotes: 0

ShaheerL
ShaheerL

Reputation: 61

There are many different ways to approach this. However, as a start to become familiar with while loops, I recommend this simple method:

System.out.println("Enter an integer smaller than 20 and larger than 0");
int num = kbReader.nextInt();

while(num > 20 || num < 0)
{
    System.out.println("That value does not meet the criteria. Please try again:");
    num = kbReader.nextInt();
}

Until the correct value is entered, the user will be asked to retry their input.

Upvotes: 0

Kunal Vohra
Kunal Vohra

Reputation: 2846

IT should be easy with do-while. I am not on my compiler right now however this you should add in your code if you are using scanner

import java.util.*;
class ExamTesterNine{
public static void main(String args[]){
Scanner kbReader= new Scanner(System.in);
int num = 0;
System.out.println("Enter an integer smaller than 20 and larger than 0");
  do{
     num=kbReader.nextInt();
   } while(num<0 && num <20);

   int result;
   int sum=0;

   for(int i=1; i<=num; i++)
   sum=sum+i;

   int [] number= new int [num];
   for (int a=0; a<(number.length-1); a++ ){
     number[a]=a+1;
     System.out.print(number[a]+"+");}
   System.out.print(num+"="+sum);
   }

  }
}

Let me know if it don't I can get on the compiler quickly however do-while is solution for you.

Upvotes: 3

Scary Wombat
Scary Wombat

Reputation: 44854

you will need a while loop as you do not know how many times the wrong input will be entered

while (true) {
  System.out.println("Enter an integer smaller than 20 and larger than 0");
  int num=kbReader.nextInt(); // get input
  // test
  if (goodInput (num)) {
      break;
  }
}

Upvotes: 1

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