Reputation: 169
Reading user input
I'm trying to ask the user to enter any number of numbers up to 5, each number seperated by space.
for example
enter up to 5 numbers : 3 4 5
I'm going to add them in the integer sum and then later divide them by counter
to get the average of these numbers.
However, my loop does not seem to end. What's wrong with my code?
int counter = 0 , sum = 0;
Scanner scan = new Scanner(System.in);
System.out.println("enter up to 5 numbers");
while(scan.hasNextInt());{
counter++;
sum += scan.nextInt();
}
System.out.println(counter);
System.out.println(sum);
Upvotes: 0
Views: 433
Answers (6)
Reputation: 11
DataInputStream in = new DataInputStream(System.in);
String[]label = {"quiz #","Total","Average"};
int counter = 0;
int theSum = 0;
System.out.print("Enter up to 5 number : ");
String[]tempNum = in.readLine().trim().split("\\s+");
System.out.println();
while (counter <= tempNum.length)
{
if ( counter == tempNum.length)
{
System.out.printf("%10s %12s\n",label[1],label[2]);
counter = 0;
break;
} else {
System.out.printf("%10s",label[0] + (counter+1) );
}
counter++;
}
while(counter <= tempNum.length)
{
if ( counter == tempNum.length)
{System.out.printf("%10d %10.2f\n",theSum,(double)(theSum/counter));
} else
{System.out.printf("%10d",Integer.valueOf(tempNum[counter]));
theSum += Integer.valueOf(tempNum[counter]);
}
counter++;
}
Upvotes: 0
Reputation: 1516
If you want to read entire line and then do arithmetic operation later then you dont need to have while loop with hasNextInt() method.
I would suggest you to read line then split by space and iterate over string array. Check out code snippet.
package com.gaurangjadia.code.java;
import java.util.Scanner;
public class SO19204901 {
public static void main(String[] args) {
int counter = 0,
sum = 0;
System.out.println("enter up to 5 numbers");
Scanner scan = new Scanner(System.in);
String strInput = scan.nextLine();
String[] arrayNumbers = strInput.split(" ");
for (int i = 0; i < arrayNumbers.length; i++) {
int n;
try {
n = Integer.parseInt(arrayNumbers[i]);
}
catch (NumberFormatException e) {
n = 0;
}
sum = sum + n;
counter++;
}
System.out.println(sum);
}
}
Upvotes: 0
Reputation: 630
int counter = 0 , sum = 0;
Scanner scan = new Scanner(System.in);
System.out.println("enter up to 5 numbers");
while(scan.hasNextInt()){
counter++;
sum += scan.nextInt();
if(counter >=5)
break;
}
System.out.println(counter);
System.out.println(sum);
scan.close();
First, you need to remove ';' located after while(scan.hasNextInt()) and before {; For the ; means the while statement is complete.
Second, when you use your code, you need CTRL + Z to end up your input. By adding
if(counter >=5)
break;
your input will end up when you input 5 numbers.
Upvotes: 0
Reputation: 1549
Everything in your code is fine except the semicolon(;) just after the while loop, of course it will lead to an infinite loop.
Upvotes: 0
Reputation: 25865
Scanner.hasNextInt() does not do what you seem to think it does. It does not tell you whether there is an integer available in already typed input (it does not have any conception of what has "been typed"), but rather whether the input waiting can be read as an integer. If there is no input already waiting, it will block until there is, so your loop is simply sitting there forever, blocking for more input.
What you probably want to do instead is to read a whole line, and then split it explicitly into space-separated parts, and only then parse those as integers. For example, like this:
String input = scan.nextLine();
for(String part : input.split(" "))
sum += Integer.parseInt(part);
Serge Seredenko's answer is also correct, however, but that's another problem.
Upvotes: 0
