java - 我有一个对象的 PriorityQueue，我需要根据浮点值对其进行排序。如何为它创建一个比较器？

Question

我已经为优先队列创建了一个比较器。

class CompareBySalary implements Comparator<Employee>{
    @Override
    public int compare(Employee e1,Employee e2){
        return e1.salary<e2.salary ? -1 : e1.salary>e2.salary ? 1 : 0;
        
    }
}

class Employee{
    String name;
    float salary;
    Employee(String name,float salary){
        this.name=name;
        this.salary=salary;
    }
}

 public class TryCode{
     
     public static void main(String args[])
     {
        
         Employee e1=new Employee("C",10000);
         Employee e2=new Employee("A",5000.45f);
         Employee e3=new Employee("D",15000);
         Employee e4=new Employee("B",5000.67f);
         Queue<Employee> q=new PriorityQueue(new CompareBySalary());
         q.offer(e1);
         q.offer(e2);
         q.offer(e3);
         q.offer(e4);
         for(Employee e:q)
             System.out.println(e.name);
            
     }
     
     
 }

这给出了输出：ABDC 为什么没有正确排序？这是我想念的东西吗？PS 我已经尝试过使用 Float.compare() 它提供相同的输出。

Answer 1

1. 更改您的域模型如下：

    class Employee implements Comparable<Employee> {
        private String name;
        private float salary;
   
        Employee(String name, float salary) {
            this.name = name;
            this.salary = salary;
        }
   
        public String getName() {
            return name;
        }
   
        public float getSalary() {
            return salary;
        }
   
        @Override
        public int compareTo(Employee o) {
            if (o1.getSalary()>o2.getSalary()) {
                return 1;
            } else if (o1.getSalary()<o2.getSalary()) {
                return -1;
            } else {
                return 0;
            }
        }
    }
   

2. 删除CompareBySalary（你不需要它）

3. 像这样创建你的PriorityQueue：

   PriorityQueue<Employee> q = new PriorityQueue<>(Comparator.comparingDouble(Employee::getSalary));