如何比较Java中两个对象的参数值？

Question

Right now I'm working on a method for comparing the scores of athletes in the olympics. So far I've had little trouble, however now I've reached a point where i need to compare two objects (athletes) scores and I'm not sure how to do it. This is my code for the Olympic class:

// A program using the Athlete class
public class Olympics {
 public static void main(String args[]) {
 System.out.println("The leader is " + Athlete.leader() +
 ", with a score of " + Athlete.leadingScore());

 Athlete meryl = new Athlete("Meryl Davis", "U.S.");
 meryl.addScore(75);
 System.out.println(meryl);

 Athlete tessa = new Athlete("Tessa Virtue", "Canada");
 System.out.println(tessa);
 System.out.println(); // blank line

 tessa.addScore(50);
 System.out.println(tessa);
 System.out.println(meryl);
 System.out.println("The leader is " + Athlete.leader() +
 ", with a score of " + Athlete.leadingScore());
 System.out.println(); // blank line

 tessa.addScore(100);
 meryl.addScore(65);
 System.out.println(tessa);
 System.out.println(meryl);
 System.out.println("The leader is " + Athlete.leader() +
 ", with a score of " + Athlete.leadingScore());
 System.out.println(); // blank line

 tessa.addScore(20);
 System.out.println("Tessa's final score is " + tessa.getScore());

 meryl.move("France");
 System.out.println(meryl);
 } // end main
} // end class Olympics

And this is the constructor class "Athlete":

public class Athlete {
    private String name;
    private String country;
    protected int score;
    public static int leadScore;
    public Athlete(String athName, String athCountry) {
        this.name = athName;
        this.country = athCountry;
        score = 0;
        if (score < 1) {
            System.out.println("Score cannot be lower than 1");
        }
    }
    public int addScore(int athScore) {
        score += athScore;
        return score;
    }
    public static String leader(){
        //TODO
    }
    public static int leadingScore() {
       //MUST COMPARE BOTH ATHLETES
    }
    public int getScore(){
        return score;
    }
    public void move(String newCountry) {
        country = newCountry;
    }
    public String toString() {
        return name + ": " + "from " + country + ", current score " + score;
    }
}

So what I'm trying to do is have the program check Meryl's score compared to Tessa's and return that Athlete's score in leadingScore() and, using that athlete, return a leader(). Any help is appreciated! Thanks.

Answer 1

The function must take the two Athletes you're comparing as the parameters for this to work

public static int leadingScore(Athlete a1, Athlete a2) {
    if (a1.getScore() < a2.getScore()) {
        // do stuff
    }
}

Answer 2

You should consider using a "collection" . Use an array, a list ... or even a sorted list.

Stored your individual objects in the collection, then traverse the collection to find the highest score.

For example:

// Create athlete objects; add each to list
ArrayList<Athlete> athletes = new ArrayList<Athlete>(); 
Athlete meryl = new Athlete("Meryl Davis", "U.S.");
meryl.addScore(75);
...
athletes.add(meryl);

Athlete tessa = new Athlete("Tessa Virtue", "Canada");
...
athletes.add(tessa );

// Go through the list and find the high scorer
Athlete highScorer = ...;
for (Athlete a : athletes) {
  if (highScorer.getScore() < a.getScore())
    highScorer = a;
  ...
}
System.out.println("High score=" + highScorer.getScore());

Here's a good tutorial:

• http://www.vogella.com/tutorials/JavaCollections/article.html

Answer 3

The lead score should not be in the athlete class, but rather in main () because one instance of an Athlete class would not know of other instances unless you put a self-referential list inside the class. Similarly, leadingScore should be in main ().

It or main can call each athlete and compare:

int merylScore = meryl.getScore ();
int tessaScore = tessa.getScore ();
int leadingScore = 0;
String leaderName = "";
if (merylScore > tessaScore) {
    leadingScore = merylScore;
    leaderName = meryl.getName ();
} else if (tessaScore > merylScore) {
    leadingScore = tessaScore;
    leaderName = tessa.getName ();
} else {
    leadingScore = merylScore;
    leaderName = "a tie between Meryl and Tessa";
}
System.out.println ("The leader is " + leaderName + ", with a score of " + leadingScore);