public class ArrayAndMethod {

    public static void printArray( int[] array )
    {
        for( int i = 0; i < array.length; ++i )
            System.out.print( array[i] + " " );
        System.out.println();
    }

    public static void inc( int n )
    {
        ++n;
    }

    public static void inc( int[] a )
    {
        ++a[0];
    }

    public static int[] createArray( int n )
    {
        int[] a = new int[n];
        for( int i = 0; i < a.length; ++i )
            a[i] = i + 1;
        return a;
    }

    public static int sum( int... numbers )
    {
        int sum = 0;
        for( int i = 0; i < numbers.length; ++i )
            sum += numbers[i];
        return sum;
    }

    public static void main( String[] args )
    {
        int n = 10;
        inc( n ); // primitive types are pass-by-value
        System.out.println( n );

        int[] a = { 10 };
        inc( a ); // arrays and objects are pass-by-reference
        System.out.println( a[0] );

        // assigning an array to another variable doesn't make a copy
        int[] b = a;
        b[0] = 100;
        System.out.println( a[0] );

        // making a copy of an array requires creating a new array, then copy
        // over the elements one by one
        b = new int[1];
        b[0] = a[0];
        b[0] = 200;
        System.out.println( b[0] + ", " + a[0] );

        int[] c = createArray( 10 );
        printArray( c );

        System.out.println( sum() );
        System.out.println( sum( 1 ) );
        System.out.println( sum( 1, 2 ) );
        System.out.println( sum( 1, 2, 3 ) );
    }

}