Using comparable interface to sort through an array

Question

I am trying to rank/sort the diamonds by size of the carat. If the size is equal then I want to rank them by either the color or the clarity, whichever gives its the best ranking. I cannot get it to work properly. It runs, however it will only rank them according to the size of the carat

Crawford_Diamond[] stones = new Crawford_Diamond[16];

stones[0] = new Crawford_Diamond( "A1023", 1.0, "VS1",  'F', "brilliant");
stones[1] = new Crawford_Diamond( "A5911", 1.1, "VVS2", 'G', "rose");
stones[2] = new Crawford_Diamond( "C5427", 1.0, "VS1",  'D', "princess");
stones[3] = new Crawford_Diamond( "D8307", 1.6, "SI1",  'H', "brilliant");
stones[4] = new Crawford_Diamond( "B4825", 0.3, "I1",   'D', "rose");
stones[5] = new Crawford_Diamond( "A1844", 2.1, "VS2",  'D', "lozenge");
stones[6] = new Crawford_Diamond( "A3747", 3.1, "SI2",  'W', "baguette");
stones[7] = new Crawford_Diamond( "E6393", 2.3, "VS2",  'I', "brilliant");
stones[8] = new Crawford_Diamond( "C5619", 2.8, "VVS1", 'E', "pear");
stones[9] = new Crawford_Diamond( "E8348", 1.4, "VS2",  'G', "brilliant");
stones[10] = new Crawford_Diamond( "D2381", 1.7, "I3",   'G', "brilliant");
stones[11] = new Crawford_Diamond( "C9253", 1.3, "VS2",  'H', "baguette");
stones[12] = new Crawford_Diamond( "G3459", 2.1, "VS2",  'H', "rose");
stones[13] = new Crawford_Diamond( "B3598", 2.4, "VVS2", 'D', "pear");
stones[14] = new Crawford_Diamond( "D9836", 2.8, "IF",   'E', "princess");
stones[15] = new Crawford_Diamond( "E1046", 2.2, "FL",   'E', "rose");

Arrays.sort(stones);

for ( int j=0; j<stones.length; j++)
    System.out.println( stones[j].toString());
public class Crawford_Diamond implements Comparable<Crawford_Diamond>
{

private String stockNumber; //diamond stock number
private double carot; //carrot size
private String clarity;  
private char color; //color of the diamond. D=Best Z=Worst
private String cut; //cut of the diamond 
private int diamondColor;
private int diamondClarity;

public Crawford_Diamond(String sN, double car, String clar, char col, String cutType)
{
    stockNumber = sN; 
    carot = car; 
    clarity = clar; 
    color = col; 
    cut = cutType;

}
//gets the stock number of the diamond
public String getStock(){return stockNumber; }

//gets the carrot size of the diamond
public double getCarot(){return carot;}

//gets the clarity of the diamond
public String getClarity(){return clarity;}

//gets the color of the diamond
public char getColor()
{

    return color;
}

//gets the cut of the diamond 
public String getCut() {return cut;}
public int compareClarity(String getClarity)
{
    int diamondClarity=0; 
    if (getClarity.equals("Fl"))
        diamondClarity = 10; 
    else if (getClarity.equals("IF"))
        diamondClarity = 9; 
    else if (getClarity.equals("VVS1"))
        diamondClarity = 8; 
    else if (getClarity.equals("VVS2"))
        diamondClarity = 7; 
    else if (getClarity.equals("VS1"))
        diamondClarity = 6; 
    else if (getClarity.equals("VS2"))
        diamondClarity = 5; 
    else if (getClarity.equals("SI1"))
        diamondClarity = 4; 
    else if (getClarity.equals("SI2"))
        diamondClarity = 3; 
    else if (getClarity.equals("I1"))
        diamondClarity = 2; 
    else if (getClarity.equals("I2"))
        diamondClarity = 1; 
    else if (getClarity.equals("I3"))
        diamondClarity = 0; 
    return diamondClarity;
}

public int getRankD1( )
{
int rankD1=0;
if (this.diamondColor > this.diamondClarity)
    rankD1 = diamondColor;  
else if (this.diamondColor < this.diamondClarity)
    rankD1 = diamondClarity;
return rankD1; 
}
public int getRankD2()
{
int rankD2=0;
if (this.diamondColor > this.diamondClarity)
rankD2 = diamondColor; 
else if (this.diamondColor < this.diamondClarity)
rankD2 = diamondClarity;
return rankD2;
}

public int compareColor(char getColor)
{
    int diamondColor=0; 
    if (getColor=='D' || getColor=='E')
        diamondColor = 10; 
    else if (getColor=='F' || getColor=='G')
        diamondColor = 9; 
    else if (getColor=='H' || getColor=='I')
        diamondColor = 8; 
    else if (getColor=='J' || getColor=='K')
        diamondColor = 7; 
    else if (getColor=='L' || getColor=='M')
        diamondColor = 6; 
    else if (getColor=='N' || getColor=='O')
        diamondColor = 5; 
    else if (getColor=='P' || getColor=='Q')
        diamondColor = 4; 
    else if (getColor=='R' || getColor=='S')
        diamondColor = 3; 
    else if (getColor=='T' || getColor=='U')
        diamondColor = 2; 
    else if (getColor=='V' || getColor=='W')
        diamondColor = 1; 
    else if (getColor=='X' || getColor=='Y')
        diamondColor = 0; 
    return diamondColor;
}

public int compareTo(Crawford_Diamond other)
{

    if (this.carot > other.getCarot())
    {
        return -1;
    }
    else if (this.carot < other.getCarot())
    {
        return 1;

    }
    else if(this.getRankD1() > other.getRankD2())
    {
        return -1;
    }
    else if(this.getRankD1() < other.getRankD2())
    {
        return 1;
    }
    else 
        return 0;}



public String toString()
{
    return "{stockNumber :: " +getStock() + " carot :: " +getCarot() + " clarity :: " +getClarity()+ " color :: " +getColor() + " cut :: " +getCut()+"}";
}
}   

Answer 1

You almost have it right. If you just add two lines to your constructor, your code will do exactly what you want.

public Crawford_Diamond(String sN, double car, String clar, char col, String cutType)
{
    stockNumber = sN; 
    carot = car; 
    clarity = clar; 
    color = col; 
    cut = cutType;

    diamondColor = compareColor(color);
    diamondClarity = compareClarity(clarity);
}

There are other things you can do to clean up your code as well. You make rename compareClarity to getClarityValue since you are just translating the string into an integer. The same goes for color.

You also do not need two versions of the ranking method. Since the method is always called on the given diamond object, a single getRank() method will work just fine in place of getRankD1() and getRankD2().

Answer 2

try ok as they are doubles not ints...

public int compareTo(Crawford_Diamond other)
{  
    int value = 0;
    if (this.carot > other.getCarot())
    {
        value = -1;
    }
    else if (this.carot < other.getCarot())
    {
        value = 1;
    }       
    if (value == 0){
       value = getRankD1() - other.getRankD1();           
    }
    return value;
}  

Answer 3

In cases like this I find it easier to give values an absolute score....

First, I would change your functions to return values in the opposite order (where Color Dhas a score of 0, and color X has a score of 10. Similarly, the best clarity ('fl' is already the high score....).

Use scores that rank the best attribute highest. You have a scale from 0 through 10.

So, I would have a method on Crawford_Diamond called getScore() which would do:

public int getScore() {
    int score = (int)(carat * 100000); // carat of 2.2 will become 220000
    int colorscore = getColorScore(color);
    int clarityscore = getClarityScore(clarity);
    if (color > clarity) {
        // color of D is best, give it score 1000 and add the clarity score
        score = score + (100 * color) + clarity;
    } else {
        score = score + (100 * clarity) + color;
    }
    return score;
}

Then, your compareTo method simply becomes:

public int compareTo(Crawford_Diamond other) {
    return other.getScore() - getScore();
}

(note, it's carat, not carot (or caret))