使用可比界面的问题

Question

I am trying to utilize the comparable interface to sort an array. The method compareTo() is written so that diamonds are ordered first by carot, then by clarity OR color, whichever is better for the particular diamond. Since there are 23 grades of color, but only 11 grades of clarity, regard the first two color grades as equal in grade to the first grade of clarity, the next two color grades equal in grade to the second grade of clarity, and so on. I'm not sure how to compare the color to the clarity since one is a string and the other is a char. Here is what I have so far.

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

}

public int compareTo(Diamond other)
{
    if (getCarot() < other.getCarot())
    {
        return 1;
    }
    else if(getCarot() > other.getCarot())
    {       
        return -1;
    }
    else return 0; 
}
public String toString()
{
    return "{stockNumber :: " +getStock() + " carot :: " +getCarot() + " clarity :: " +getClarity()+ " color :: " +getColor() + " cut :: " +getCut()+"}";
    }


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

//gets the carot 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; 
}

Diamond[] stones = new Diamond[16];

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

Arrays.sort( stones );

for ( int j=0; j<stones.length; j++ )
  System.out.println( stones[j].toString() );

}

}

Answer 1

While doing compare with multiple params, we should keep returning 0 at the last and keep on comparing the params on priority. Below is the code to sort on Carot, color and clarity.

You can add more conditions between color and clarity as per your requirement.

public int compareTo(Crawford_Diamond other) {
        if (getCarot() < other.getCarot()) {
            return 1;
        } else if (getCarot() > other.getCarot()) {
            return -1;
        }

        if (this.color < other.getColor()) {
            return 1;
        } else if (this.color > other.getColor()) {
            return -1;
        }

        if (this.clarity.compareTo(other.getClarity())<1) {
            return 1;
        } else if (this.clarity.compareTo(other.getClarity())>1) {
            return -1;
        }
        return 0;
    }