How to compare three integer values?

Question

I have three integer values along with its text. My requirement is to give rank to all of them.

E.g. I have A = 50 points, B = 500 Points, C = 50 points.

Now I would like to compare all of these and find max and equal values and its according name(like, A/B/C).

EDIT :: As a output it should return, B = 1st Rank, A = 2nd Rank, C = 2nd Rank.

If anyone has any idea about how can I implement code as per my requirement then, it would be great.

Thanks in advance.

public class ScoreVO implements Comparator<Integer> {

    private String playerName = Constants.BLANK_STRING;
    private int playerScore;

    public String getPlayerName () {
        return playerName;
    }

    public void setPlayerName ( String playerName ) {
        this.playerName = playerName;
    }

    public int getPlayerScore () {
        return playerScore;
    }

    public void setPlayerScore ( int playerScore ) {
        this.playerScore = playerScore;
    }

    @Override
    public int compare ( Integer o1, Integer o2 ) {
        return o2.compareTo ( o1 );
    }
}

Here is my class with Comparator<>.

Please suggest me if I am wrong.

Answer 1

A sample running code which gives output shown below as per your requirement along with player rank. There is a separate method assignRank(List<>) which you can use to assign ranks to players.

Score List: [ScoreVO [playerName=B, playerScore=500, playerRank=1], ScoreVO [playerName=A, playerScore=50, playerRank=2], ScoreVO [playerName=C, playerScore=50, playerRank=2]]

public class ScoreExample {

    public static void main(String[] args) {
        List<ScoreVO> scoreList = new ArrayList<ScoreVO>();
        scoreList.add(new ScoreVO("A", 50));
        scoreList.add(new ScoreVO("C", 50));
        scoreList.add(new ScoreVO("B", 500));
        Collections.sort(scoreList);
        assignRank(scoreList);
        System.out.println("Score List: "+scoreList);
    }

    private static void assignRank(List<ScoreVO> scoreList) {
        int rank = 0;
        int score = 0;
        for(ScoreVO scoreVO : scoreList) {
            if(score != scoreVO.getPlayerScore()) {
                rank++;
                scoreVO.setPlayerRank(rank);
                score = scoreVO.getPlayerScore();
            } else {
                scoreVO.setPlayerRank(rank);
            }
        }
    }
}
class ScoreVO implements Comparable<ScoreVO> {
    public String playerName;
    public int playerScore;
    public int playerRank;

    public ScoreVO(String playerName, int playerScore) {
        this.playerName = playerName;
        this.playerScore = playerScore;
    }

    public String getPlayerName() {
        return playerName;
    }

    public void setPlayerName(String playerName) {
        this.playerName = playerName;
    }

    public int getPlayerScore() {
        return playerScore;
    }

    public void setPlayerScore(int playerScore) {
        this.playerScore = playerScore;
    }

    public int getPlayerRank() {
        return playerRank;
    }

    public void setPlayerRank(int playerRank) {
        this.playerRank = playerRank;
    }

    @Override
    public int compareTo(ScoreVO o) {
        if(o.getPlayerScore() != getPlayerScore()) {
            if(getPlayerScore() > o.getPlayerScore())
                return -1;
            else
                return 1;
        } 
        return getPlayerName().compareTo(o.getPlayerName());
    }

    @Override
    public String toString() {
        return "ScoreVO [playerName=" + playerName + ", playerScore="
                + playerScore + ", playerRank=" + playerRank + "]";
    }
}

Answer 2

ScoreVO should implement Comparable<ScoreVO>. And your compareTo method looks like this:

@Override
public int compareTo ( ScoreVO o ) {
    if(playerScore != o.playerScore)
       return Integer.compare(playerScore, o.playerScore);
    return playerName.compareTo(o.playerName);
}

Answer 3

You should implment Comparable for ordering purpuses, and equals() for equation (that can use compareTo)

like this

public class ScoreVO implements Comparable<ScoreVO> {

    @Override
    public int compareTo(ScoreVO other) {
        return other == null ? 1 : getPlayerScore() - other.getPlayerScore();
    }

    @Override
    public boolean equals(object other) {
        return !(other instanceof ScoreVO) ? false : compareTo(other) == 0 ;
    }
}

However, you probably want to compare equality based on player name. think of putting ScoreVO object in a map - what is the key? so -

    @Override
    public boolean equals(object other) {
        return other == null  ||  !(other instanceof ScoreVO) ? false :             
               getPlayerName.equals(other.getPlayerName()) ;
    }

Answer 4

As there are just three values, it is possible to hard-code all operations. You can think of a very compact and efficient way to work this out.

Every comparison of two values can give an outcome >, = or <. Assigning the value 0, 1 or 2 to these, you can pack the three comparisons in a single number using base 3 encoding. You will end up with a number in range 0 to 26, and every different value corresponds to a different answer that you can tabulate (or process in a switch statement).

int Compare(int A, int B) { return A > B ? 0 : (A == B ? 1 : 2); }

char* Answer[27]= { "A1B2C3", "A1B1C3", "B1A2C3", ... }; // To be filled
return Answer[Compare(A, B) + 3 * compare(B, C) + 9 * compare(A, C)];