/** Demonstrate poor and good ways to map a loop index to a desired value. */
public class CalcDirection
{

    /** A bonehead solution */
    public void bigMethod()
    {
        for(int dir=0; dir < 4; dir++)
        {
            switch (dir)
            {
                case 0: 
                    System.out.println("Some big calculation using 0");
                    break;
                case 1:
                    System.out.println("Some big calculation using 90");
                    break;
                case 2:
                    System.out.println("Some big calculation using 180");
                    break;
                case 3:
                    System.out.println("Some big calculation using 270");
                    break;
            }
        }
    }

    /** A poor solution - redundant code */
    public void smallMethod()
    {
        System.out.println("Some big calculation using 0");
        System.out.println("Some big calculation using 90");
        System.out.println("Some big calculation using 180");
        System.out.println("Some big calculation using 270");
    }
//------------------------------------------------------------------------    
    public void useLookupTable(int direction)
    {
        final int[] degrees = {0,90,180,270};
        System.out.println("Some big calculation using " + degrees[direction]);
    }        

    /** An acceptable solution - use a lookup table */
    public void noRedundantCode1()
    {
        // First Approach
        for(int dir=0; dir < 4; dir++)
        {
             useLookupTable(dir);
        }
    }
//------------------------------------------------------------------------
    /** A good solution - uses an enumeration type */
    private enum Directions {north, east, south, west};
    public void useEnum()
    {
        // Third Approach - avoid magic numbers
        for(Directions dir : Directions.values())
        {
             useLookupTable(dir.ordinal());
        }
    }
//------------------------------------------------------------------------    
    /** A clever good solution - use a formula to map direction to degrees */
    public void doCalculation(int direction)
    {
        int degrees = direction * 90;
        System.out.println("Some big calculation using " + degrees);
    }        

    public void noRedundantCode2()
    {
        // Second Approach - smart!
        for(int dir=0; dir < 4; dir++)
        {
             doCalculation(dir);
        }
    }
//------------------------------------------------------------------------
    public static void main(String[] args)
    {
        new CalcDirection().bigMethod();
        new CalcDirection().smallMethod();
        new CalcDirection().noRedundantCode1();
        new CalcDirection().noRedundantCode2();
        new CalcDirection().useEnum();
    }

}