Java problem

telomar · 30-11-2004 06:13PM #1

Getting an error reading in number from the output in netbeans. The code looks like

import java.util.Scanner;
import static java.lang.System.out;
class take_in {
    
    
    public take_in() {
    }
    
    
    public static void main(String[] args) {
        Scanner myscanner = new Scanner(System.in);
        System.out.print("Enter a number: ");
        int input = myscanner.nextInt();
        
    }
    
}

and the errors are:

Exception in thread "main" java.util.NoSuchElementException
at java.util.Scanner.throwFor(Scanner.java:817)
at java.util.Scanner.next(Scanner.java:1431)
at java.util.Scanner.nextInt(Scanner.java:2040)
at java.util.Scanner.nextInt(Scanner.java:2000)
at take_in.main(take_in.java:13)

Help would be greatly appreciated

Hobbes · 30-11-2004 08:44PM

you get the error straight away? Or after you type something in? Have you tried typing something in like "1 2 3 " or "1" or "1 ". What do they do?

Or does system.in require piping? (although the API doc says it will block for input).

telomar · 30-11-2004 08:54PM

doesn't allow you to type something in. problem seems to occur at the instantiation of the input:

int input = myscanner.nextInt();

it runs i.e. when you run it, it prints that "Enter... " to the screen but wont let you enter anything. if you try sticking in a system.out statement after that int input... it wont print to the screen. Well stumped here.

aidan_walsh · 30-11-2004 08:59PM

Try inserting an BufferedReader in place of directly hooking into System.in.

telomar · 30-11-2004 09:08PM

This code here uses BufferedReader and has it working:
[code]import java.io.* ;

class Tut1{

public static void main(String args[])

{

InputStreamReader istream = new InputStreamReader(System.in) ;

BufferedReader bufRead = new BufferedReader(istream) ;

System.out.println("Welcome To My First Java Program");

try {

System.out.println("Please Enter In Your First Name: ");

String firstName = bufRead.readLine();

System.out.println("Your Name is: " + firstName);

}

catch (IOException err) {

System.out.println("Error reading line");

}

}

}

[\code]

Just can't understand why that Scanner file ain't working. Could it be a problem in the written code?

aidan_walsh · 30-11-2004 09:11PM

It seems to me that using just System.in doesn't break for input like its supposed to, but I always found it better to use a BufferedReader just to be on the safe side.

telomar · 30-11-2004 09:19PM

Yeah its annoying me here... Gonna just leave it. Cheers for the help.

tempest · 01-12-2004 11:02AM

The problem is that scanner.nextInt() is being called before anything has been entered on standard input. The contract of the method clearly states that a NoSuchElementException will be raised if the input is exhausted. i.e. a token cannot be retrieved.

try this.

    public static void main(String[] args) {
        Scanner myscanner = new Scanner(System.in);
        System.out.print("Enter a number: ");
        while (true) {
          if (myscanner.hasNextInt())  {
            int input = myscanner.nextInt();
            System.out.println("You entered: " + input);
          }
        }
        
    }

MidnightQueen · 02-12-2004 09:07PM

Is there by any chance a way of putting "if statements" within "for loops" for java?

aidan_walsh · 02-12-2004 09:09PM

for(int i = X; i <= Y; i++)
{
   if(true)
   {
   }
}

MidnightQueen · 02-12-2004 09:15PM

Thank you!

but it goes a little something like this but i dont think its working properly.

String employee= "Caterina";
double rate= 10.25;
int hoursPerWk= Console.readInt("Enter the Hours Per Week: ");
double salary= rate * hoursPerWk;

for(hoursPerWk=0; hoursPerWk>0; hoursPerWk++)
{
System.out.println(hoursPerWk);

if(hoursPerWk>40)
{
System.out.println("Time and a Half\t" + salary);
}
}

tempest · 03-12-2004 09:52AM

String employee= "Caterina";
double rate= 10.25;

/* get the hours per week */
int hoursPerWk= Console.readInt("Enter the Hours Per Week: ");
double salary= rate * hoursPerWk;

/* 
    Ignore hours per week. Reset the value to 0.
    start off a loop that will never execute as the condition
    will never be met.
*/
for(hoursPerWk=0; hoursPerWk>0; hoursPerWk++)
{
  System.out.println(hoursPerWk);

  if(hoursPerWk>40)
  {
    System.out.println("Time and a Half\t" + salary);
  }
}

And in English:
Basically you are reading in a value and then resetting it in the for loop (hoursPerWk = 0).
Solution:
Use a while loop.
Lesson:
Always consider what the most appropriate looping structure is for what you want to achieve.

hoursPerWk=0; hoursPerWk>0;
hoursPerWk cannot be both equal to 0 and greater than 0 at the same time. therefore the loop can never execute....

Also you should probably have started a separate thread..

Thordon · 03-12-2004 12:44PM

public take_in() {
}

Calling a class take_in makes me sad

, humpback style is preffered over underscores since java is case sensetive and classes are supposed to start with a capital letter (String for example).

MidnightQueen · 06-12-2004 10:37AM

Thanks for the help!

I'm still only a rookie at Java but i'll try my best to help yee solve your problems too.

Java problem

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