Functions can be passed things such as variables and arrays
 etc. so that the function can play with the values in the variables
or arrays.

Functions have the ability to return a single value by using
the return command followed by the variable or value being
returned. NOTE:: Functions declared to be of type 'void'
will not return a value. All other type will return a value. These
values are returned back to the program that called the function.

Functions are called by referring to the name of the function
followed by an optional parameter list of things to be passed
to the function. 

Functions can only play with variables that:
1  declared within the function (local)
2  values passed to the function
3  global variables declared above the function but not
    inside another function

 Examples of calling 3 functions

        fun1();         // call a function passing nothing

        int a=3;
        int b=11;
        int c=fun2(a,b);    // call a function passing 2 values both int
                                      // fun2 returns a value that is put into c

        int scores[] = new int[10];      // declare int array
        fun3(scores);         // call fun3 passing scores by reference

     
 Examples of the 3 functions that were called above      

      public void fun1()       // void  means no value returned
        {
           JOptionPane.showMessageDialog(null,"hello");
         }

      public int fun2(int n1, int n2)
        {
           int n3;
           n3 = n1 * n2;
           return n3;
         }

        public void fun3(int numbers[] )    // pass array by reference
         {
            for (int a=0;a<10;a++)
               numbers[a] = a * 10;
          }

// note in the last function  'fun3' it puts values in 'numbers' array
// but in fact it is putting values in the 'scores' array. Called
// passing by reference. 'numbers' is merely another name
// for the memory locations of the 'scores' array.