Java problem

telomar

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

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

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

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

telomar

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

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

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

tempest

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

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

aidan_walsh

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

MidnightQueen

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

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

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

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.