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class Foo {
public static void main(String[] args) {
int num = 10;
num = doubleUp(num);
System.out.println(num);
}

public static int doubleUp(int num) {
...

http://www.javaprogrammingforums.com/content/37-first-time-here-please-read.html <--- please read on how to correctly post your code.

Use "try catch" blocks to handle the exception.

The...