Question

我有一个实现Comparable的User类。在我将用户列表添加到PriorityQueue<User>后，他们应按scores排列优先级，但出于某种原因，他们不会。Queue。你能否帮我弄清楚为什么用户没有在prioritisedUsers.poll()中排序？

更新

我通过轮询元素访问队列。 PriorityQueue<User> prioritisedUsers = userPriorityStrategy.computeUserPriority(users); while(!prioritisedUsers.isEmpty()){ System.out.println(prioritisedUsers.poll().getPriorityScore()); }它始终带有顺序尊重的随机分数。

0.35036433736768735
0.6619121139678329
0.09520067929838127
0.4013591573863
0.6704568389588227
0.5989900926939181
0.7320779721160738

输出：

public class User implements Comparable<User>{

    private long id;
    private String fistName;
    private String lastName;
    private double priorityScore;

    public User (long id, String firstName, String lastName){
        this.id = id;
        this.fistName = firstName;
        this.lastName = lastName;
    }

    public double getPriorityScore(){
        return this.priorityScore;
    }

    public void setPriorityScore(double priorityScore){
        this.priorityScore = priorityScore;
    }

    public long getId(){
        return this.id;
    }

    public String getFistName(){
        return this.fistName;
    }

    public String getLastName(){
        return this.lastName;
    }

    public int compareTo(User o) {
        return (int) (this.getPriorityScore() - o.getPriorityScore());
    }
}


    public PriorityQueue<User> computeUserPriority(List<User> users) {
        PriorityQueue<User> prioritisedUsers = new PriorityQueue<User>(users.size());
        for (User user : users) {
            user.setPriorityScore(rand.nextDouble());
            prioritisedUsers.add(user);
        }
        return prioritisedUsers;
    }

感谢您的帮助！

{{1}}

Answer 1

我不太确定你的转换为（int）效果如何......因为转换为int会隐式丢弃任何小数。

如果我没错，请尝试类似

的内容

public int compareTo(User object) {
if (this.getPriorityScore() < object.getPriorityScore())
    return -1;
if (this.getPriorityScore() == object.getPriorityScore())
    return 0;
return 1;
}

或者更简单地说：

public int compareTo(User o) {
    return Double.compare(this.getPriorityScore(), o.getPriorityScore());
}

PriorityQueue命令不正确JAVA

1 个答案: