Input problem

[Sotsiak]

Hello again, so after some help I got from here and fixing a lot of errors I finally got my program running, but.. it seems there is a problem with input.

So, the code is this:

import java.io.*;

class Vehicle{
 private String number;
 private char status;
 private int years;

 Vehicle(String n, char s, int y){
  number=n;
  status=s;
  years=y;
 }

 public static int [] CalculateFee(Vehicle table[]){
  int Fee[]=new int[table.length];
  for(int i=0; i<table.length; i++){
   if(table[i].status=='1')
    Fee[i]=200;
   else if(table[i].status=='2')
    Fee[i]=2000;
   else 
    Fee[i]=1000;
  
  if(table[i].years<=5)
   Fee[i]+=30;
  else if(table[i].years<=10)
   Fee[i]+=60;
  else if(table[i].years<=15)
   Fee[i]+=90;
  else 
   Fee[i]+=120;
  }
  return Fee;
 }

 public String GetNumber(){
  return number;
 }
}

class VehicleDemo1{
 public static void main(String args[]) throws IOException{
  BufferedReader br=new BufferedReader(new InputStreamReader(System.in));

  String n;
  char s;
  int y;

  System.out.println("How many vehicles you want to give for calculation: ");
  int many=Integer.parseInt(br.readLine());
  System.out.println();

  Vehicle table[]=new Vehicle[many];

  for(int i=0; i<table.length; i++){
   System.out.println(i+" vehicle");
   System.out.println("Type the number of the vehicle: ");
   n=br.readLine();
   System.out.println("Type the status of the vehicle (1=legal, 2=illegal, 3=under investigation): ");
   s=(char) System.in.read();
   System.out.println("Type the years the vehicle is being used: ");
   y=Integer.parseInt(br.readLine());

   table[i]=new Vehicle(n, s, y);
  }

  int Fee[]=new int[table.length];
  Fee=Vehicle.CalculateFee(table);
  
  for(int i=0; i<table.length; i++){
   System.out.println("The vehicle with the number "+table[i].GetNumber()+" has a fee of "+Fee[i]+" euro");
   System.out.println();
  }
 }
}

When I get to this line "y=Integer.parseInt(br.readLine());" I get a NumberFormatException. For input string "". What exactly this means. I didn't input anything at all. I suspect it has to do with earlier inputs but I, honestly, don't understand.

In fact, I have many problems with inputs in lots of programs where I ask for input and it says the question 3 times before it lets me type.

I believe that java inputs something by itself before letting me type.
Any idea ? Thanks :)

[JosAH]

I believe that java inputs something by itself before letting me type.
Any idea ? Thanks :)

Suppose you want to read an int followed by any String value, so you do:

int i= scanner.nextInt();
String s= scanner.readLine();

And you duly type "123<enter>foo<enter>"; where <enter> is the character for your enter key. The nextInt() reads the integer 123 fine but leaves the following characters in the input buffer: "<enter>foo<enter>" because they cannot be part of an integer. When your scanner wants to read an entire line it 'sees' the first <enter> character and assumes an empty line so it returns "".

So after reading an int as the last token on a line always put a dummy scanner.readLine() call in there to get rid of that pending <enter> character.

kind regards,

Jos