How to read input with multiple lines in Java

Question

Our professor is making us do some basic programming with Java, he gave a website and everything to register and submit our questions, for today I need to do this one example I feel like I'm on the right track but I just can't figure out the rest. Here is the actual question:

**Sample Input:** 10 12 10 14 100 200  **Sample Output:** 2 4 100 

And here is what I've got so far :

public class Practice {      public static int calculateAnswer(String a, String b) {         return (Integer.parseInt(b) - Integer.parseInt(a));     }      public static void main(String[] args) {         System.out.println(calculateAnswer(args[0], args[1]));     } } 

Now I always get the answer 2 because I'm reading the single line, how can I take all lines into account? thank you

For some strange reason every time I want to execute I get this error:

C:\sonic>java Practice.class 10 12 Exception in thread "main" java.lang.NoClassDefFoundError: Fact Caused by: java.lang.ClassNotFoundException: Fact.class         at java.net.URLClassLoader$1.run(URLClassLoader.java:20         at java.security.AccessController.doPrivileged(Native M         at java.net.URLClassLoader.findClass(URLClassLoader.jav         at java.lang.ClassLoader.loadClass(ClassLoader.java:307         at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.         at java.lang.ClassLoader.loadClass(ClassLoader.java:248 Could not find the main class: Practice.class.  Program will exit. 

Whatever version of answer I use I get this error, what do I do ?

However if I run it in eclipse Run as > Run Configuration -> Program arguments

10 12 10 14 100 200 

I get no output

EDIT

I have made some progress, at first I was getting the compilation error, then runtime error and now I get wrong answer, so can anybody help me what is wrong with this:

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.math.BigInteger;  public class Practice {      public static BigInteger calculateAnswer(String a, String b) {         BigInteger ab = new BigInteger(a);         BigInteger bc = new BigInteger(b);         return bc.subtract(ab);     }      public static void main(String[] args) throws IOException {         BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));          String line;           while ((line = stdin.readLine()) != null && line.length()!= 0) {              String[] input = line.split(" ");              if (input.length == 2) {                  System.out.println(calculateAnswer(input[0], input[1]));              }          }      } } 

Answer 1

I finally got it, submited it 13 times rejected for whatever reasons, 14th "the judge" accepted my answer, here it is :

import java.io.BufferedInputStream; import java.util.Scanner;  public class HashmatWarrior {      public static void main(String args[]) {         Scanner stdin = new Scanner(new BufferedInputStream(System.in));         while (stdin.hasNext()) {             System.out.println(Math.abs(stdin.nextLong() - stdin.nextLong()));         }     } }