Java对象数组排序的三种方法->comparable，comparator，lambda表达式

以Employee为例，实现对象数组Employee[] employees的排序

1.类实现comparable

一个对象数组若要使用Arrays.sort(Object[] objects)方法来排序，那么该对象类需要实现comparable接口

public class Employee implements Comparable<Employee>{
    private String name;
    private double salary;

    public Employee(){
        name="Employee";
        salary=0;
    }

    public Employee(String name,double salary){
        this.name=name;
        this.salary=salary;
    }

    ...省略代码...

    public double getSalary(){
        return salary;
    }

    public void setSalary(double salary){
        this.salary=salary;
    }

    @Override
    public int compareTo(Employee o){
        //return Double.compare(salary,o.salary);
        return Double.compare(this.getSalary(),o.getSalary());
    }
}

        //1.Employee实现Comparable接口
        Arrays.sort(employees);

2.往Arrays.sort()方法中传入Comparator对象来规定排序规则

class EmployeeComparator implements Comparator<Employee>{
    @Override
    public int compare(Employee o1,Employee o2){
        return Double.compare(o1.getSalary(),o2.getSalary());
    }
}

        //2.使用Comparator比较器
        Comparator comparator=new EmployeeComparator();

3.往Arrays.sort()方法传入lambda表达式

        //3.使用Lambada表达式
        Arrays.sort(employees,(o1,o2)->{
            if(o1.getSalary()>o2.getSalary())return 1;
            else return -1;
        });