Comparator详解

集合递增 o1 > o2(1)     o1 == o2(0)     o1 < o2(-1)
集合递减 o1 < o2(1)     o1 == o2(0)     o1 > o2(-1)

public class ComparatorDemo {
    public static void main(String[] args) {
        final List<Medal> medals = new ArrayList<Medal>();
        medals.add(new Medal(8, "冠军"));
        medals.add(new Medal(7, "亚军"));
        medals.add(new Medal(9, "季军"));
        Collections.sort(medals, new Comparator<Medal>() {
            public int compare(Medal o1, Medal o2) {
                if (o1.getCount() == o2.getCount()) {
                    return 0;
                }
                return o1.getCount() > o2.getCount() ? 1 : -1;
            }
        });
        System.out.println(medals.toString());
    }
}

class Medal {
    private int count;
    private String name;
    
    public Medal() {}
    
    public Medal(int count, String name) {
        this.count = count;
        this.name = name;
    }
    
    public int getCount() {
        return count;
    }
    
    public void setCount(int count) {
        this.count = count;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }

    @Override
    public String toString() {
        return "Medal [count=" + count + ", name=" + name + "]\n";
    }
}