java - 使用可比较的排序字符串属性

Question

我有一个员工类和一个客户类。我可以通过员工的 id 和年龄使用 compareTo() 进行排序，因为它们是整数类型。但如何按员工姓名或薪水排序？compareTo 不接受除 int 以外的任何数据类型，抛出编译时异常。

public class Employee implements Comparable<Employee> {

    private int id;
    private String name;
    private int age;
    private long salary;

    public int getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public long getSalary() {
        return salary;
    }

    public Employee(int id, String name, int age, int salary) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    @Override
    public int compareTo(Employee emp) {
        //let's sort the employee based on id in ascending order
        //returns a negative integer, zero, or a positive integer as this employee id
        //is less than, equal to, or greater than the specified object.
        return (this.age - emp.age);
    }

    @Override
    //this is required to print the user friendly information about the Employee
    public String toString() {
        return "[id=" + this.id + ", name=" + this.name + ", age=" + this.age + ", salary=" +
                this.salary + "]";
    }

}

客户端类

import java.util.Arrays;

public class Test {

    public static void main(String a[]){

        //sorting custom object array
        Employee[] empArr = new Employee[4];
        empArr[0] = new Employee(10, "Mikey", 25, 10000);
        empArr[1] = new Employee(20, "Arun", 29, 20000);
        empArr[2] = new Employee(5, "Lisa", 35, 5000);
        empArr[3] = new Employee(1, "Pankaj", 32, 50000);

        //sorting employees array using Comparable interface implementation
        Arrays.sort(empArr);
        System.out.println("Default Sorting of Employees list:\n"+Arrays.toString(empArr));

    }
}

我刚刚用谷歌搜索似乎我也可以通过实现比较器来实现它

public static Comparator<Employee> SalaryComparator = new Comparator<Employee>() {

        @Override
        public int compare(Employee e1, Employee e2) {
            return (int) (e1.getSalary() - e2.getSalary());
        }
    };

建议使用比较器或

@Override
public int compareTo(Employee emp) {
// compare salaries, using the builtin Long.compare:
    return Long.compare (salary, emp.salary);
}

Answer 1

如果想根据名字排序，可以试试

@Override
    public int compareTo(Employee emp) {
        return this.name.compareTO(emp.name);
    }