Comparable和Comparator

package com.sk;

import java.util.Arrays;

public class compare2 {
  public static void main(String[] args) {
    Employee[] staff=new Employee[4];
    staff[0]=new Employee("sk",10000.0);
    staff[1]=new Employee("sk3",110000.0);
    staff[2]=new Employee("sk4",80000.0);
    staff[3]=new Employee("sk2",70000.0);
    //该方法在对对象数组进行排序时，对象必须实现comparable接口
    Arrays.sort(staff);
    for (Employee employee : staff) {
        System.out.println(employee.getName()+":"+employee.getSalary());
    }
}
    
    

}
class Employee implements Comparable<Employee>{
    private String name;
    private Double salary;
    public String getName() {
        return name;
    }
    public Employee(String name, Double salary) {
        super();
        this.name = name;
        this.salary = salary;
    }
    public void setName(String name) {
        this.name = name;
    }
    public Double getSalary() {
        return salary;
    }
    public void setSalary(Double salary) {
        this.salary = salary;
    }
    @Override
    public int compareTo(Employee other) {
        /**
         * Double.compare(x,y)方法：比较两个double值，x>y返回1。
         * 
         * compareTo方法的返回值为一个整型数值，如果两个对象不相等，则返回一个正值或负值。
         * 在对两个整数进行比较时，可以返回相减值，但是不适用于浮点型
         * 因为两个浮点数接近但又不想等时，他们的差四舍五入可能变成0；所以调用Double.compare方法
         */
        return Double.compare(salary,other.salary);
    }
    
}

package com.sk;

import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Comparator;

public class compare implements Comparator<String>{

    @Override
    public int compare(String o1, String o2) {
        return o1.length()-o2.length();
    }
    public static void main(String[] args) {
        String [] strings={"3333","44"};
        //使用此方法，对象必须实现Comparator接口
        Arrays.sort(strings, new compare());
        for(int x=0;x<strings.length;x++)
        {
            System.out.println(strings[x]);
        }
    }
    

}