无法调用Collections.sort(arrayList)

Question

我试图Employee通过员工的工资来对对象的arylylist进行排序.我已经存储了所有Employee对象ArrayList并试图调用Collections.sort(list)但是有错误(eclipse).请看截图

我该怎么办.？
我在实现Comparable <>接口时出现此错误,我已经添加了方法compareTo

Answer 1

你的类Employee必须实现Comparable使用Collections.sort(),你必须定义如何Employee在compareTo(Employee e)方法中比较对象.

所以在你的上下文中,它应该是这样的:

public class Employee implements Comparable<Employee> {

    public int compareTo(Employee o) {
        //this is an example. Obviously, you can put whatever you want here 
        return (int)(this.salary-o.salary);
    }
}