Question

我有一个包含两个属性的类：

public class player{
    public player(String playerName,int points){
        this.playerName=playerName;
        this.points=points;
    }
    public String getPlayerName() {
        return playerName;
    }
    public void setPlayerName(String playerName) {
        this.playerName = playerName;
    }
    public int getPoints() {
        return points;
    }
    public void setPoints(int points) {
        this.points = points;
    }
    private String playerName;
    private int points;
}

我有arrayList类包含palyer对象的集合。

List palyers=new ArrayList();
players.add(new player("mike",2));
players.add(new player("steve",3));
players.add(new player("jhon",7));
players.add(new player("harry",5);

我的问题是如何显示点差最小的玩家名称。

输出：

Based on the example code i written:

Mike and steve is the output

THis way comparison should happen:

mike to steve --> 1

mike to jhon--->5

mike to harry-->3

steve to mike -->1
steve to jhon--->5
steve to harry--->3

jhon to mike-->5
jhon to steve-->4
jhon to harry--->2

harry to mike -->3

harry to steve-->2

harry to jhon -->2

Based on above comparison mike and steve should display

用于比较属性的任何Java API？

Answer 1

使用anonymous inner class，Comparator和Collections.sort()：

    Collections.sort(palyers, new Comparator(){
        public int compare(Object o1, Object o2){
            player p1 = (player) o1;
            player p2 = (player) o2;

            return p1.getPoints().compareTo(p2.getPoints());
            }
        });.

Answer 2

撰写Comparator并使用它按点List排序。您只是比较Player个实例。

Answer 3

是的，用player课程实施Comparable（请使用“播放器”，课程大写第一个字母，否则会让人感到困惑）：

public class Player implements Comparable<Player>
{


....


    public int compareTo(Player other)
    {
        if (this.points == other.points)
            return 0;
        if (this.points > other.points)
            return 1;
        return -1;
    }

}

然后，您可以使用List

对Collections.sort(players);进行排序

Answer 4

所以你想知道那些得分差异最小的球员？虽然Apache Commons Collections中可能存在某些内容，但我认为没有API功能。

否则你将不得不使用嵌套循环。

int res1 = -1, res2 = -1;

int maxDiff = Integer.MAX_VALUE;
for ( int i = 0; i < players.size( ); i++ )
{
    for ( int j = i + 1; j < players.size() ; j++ )
    {
        int diff = Math.abs( players.get(i).getPoints( ) - players.get(j).getPoints( ) );
        if ( diff < maxDiff )
        {
            maxDiff = diff;
            res1 = i;
            res2 = j;
        }           
    }
}
System.out.println(players.get(res1).getPlayerName( ) + " and " + players.get(res2).getPlayerName( ));

显然，这段代码需要一些工作;例如，如果两对玩家之间具有相同的差异，则仅报告处理的最新对。您可能还想重新处理这段代码以删除默认值（例如，如果您的List包含0个玩家，请注意System.out.println将如何崩溃）。我留下这些给你解决。 HTH。

Pojo类属性的比较

4 个答案: