ArrayList排序

package LESSON11;
import java.util.ArrayList;
class Employee{
    private String name;
    private int age;
    private double salary;
    public Employee(String name,int age,double salary) {
        this.name=name;
        this.age=age;
        this.salary=salary;      
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public double getSalary() {
        return salary;
    }
    public void setSalary(double salary) {
        this.salary = salary;
    }    
}
public class exercise2 {
    /**
     定义一个Employee类，属性:  name：String，age：int，salary：double 
           把若干Employee对象放在List中,排序并遍历输出,排序规则：salary高的在前面，
    salary相同时age大的在前面，age也相同时按照name的字典顺序排列（a-z排列）
     */
    public static void main(String[] args) {
        Employee emp1=new Employee("jack", 20, 3000);
        Employee emp2=new Employee("jerry", 20, 3000);
        Employee emp3=new Employee("rose", 30, 5000);
        Employee emp4=new Employee("lucy", 40, 5000);
        Employee emp5=new Employee("tom", 30, 7000);
        
        ArrayList<Employee> list=new ArrayList<Employee>();
        list.add(emp1);
        list.add(emp2);
        list.add(emp3);
        list.add(emp4);
        list.add(emp5);
        
        
        //冒泡
        for (int i = 0; i < list.size()-1; i++) {//遍数
            for (int j = 0; j < list.size()-1-i; j++) {//次数
                Employee e1=list.get(j);//获取被比较的对象
                Employee e2=list.get(j+1);
                if(e1.getSalary()<e2.getSalary()){//比较薪资                
                    list.set(j, e2);//交换位置
                    list.set(j+1, e1);
                }else if(e1.getSalary()==e2.getSalary()){
                    if(e1.getAge()<e2.getAge()){//比较年龄
                        list.set(j, e2);//交换位置
                        list.set(j+1, e1);
                    }else if(e1.getAge()==e2.getAge()){
                        if(e1.getName().compareTo(e2.getName())>0){//比较姓名
                            list.set(j, e2);//交换位置
                            list.set(j+1, e1);
                        }                      
                    }                                        
                }                                
            }            
        }
        for (int i = 0; i < list.size(); i++) {
            System.out.println(list.get(i).getName()+"	"+list.get(i).getAge()+"	"+list.get(i).getSalary());            
        }                                                                                                               
    }
}

package LESSON11;
import java.util.ArrayList;
import java.util.Collections;
class Employee implements Comparable<Employee>{
    private String name;
    private int age;
    private double salary;
    public Employee(String name,int age,double salary) {
        this.name=name;
        this.age=age;
        this.salary=salary;
        
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public double getSalary() {
        return salary;
    }
    public void setSalary(double salary) {
        this.salary = salary;
    }
    @Override
    public int compareTo(Employee o) {
        // this表示当前对象
        if(o.salary==this.salary){
            if(o.age==this.age){
                return this.name.compareTo(o.name);
            }
            return o.age-this.age;
        }
        return (int)(o.salary-this.salary);
    }
    
    
}
public class exercise2 {

    /**
     定义一个Employee类，属性:  name：String，age：int，salary：double 
           把若干Employee对象放在List中,排序并遍历输出,排序规则：salary高的在前面，
    salary相同时age大的在前面，age也相同时按照name的字典顺序排列（a-z排列）
     */
    public static void main(String[] args) {
        Employee emp1=new Employee("jerry", 20, 3000);
        Employee emp2=new Employee("jacky", 20, 3000);
        Employee emp3=new Employee("rose", 30, 5000);
        Employee emp4=new Employee("lucy", 40, 5000);
        Employee emp5=new Employee("tom", 30, 7000);    
        ArrayList<Employee> list=new ArrayList<Employee>();
        list.add(emp1);
        list.add(emp2);
        list.add(emp3);
        list.add(emp4);
        list.add(emp5);    

        Collections.sort(list);    

        for (int i = 0; i < list.size(); i++) {        System.out.println(list.get(i).getName()+"	"+list.get(i).getAge()+"	"+list.get(i).getSalary());
            
        }    
    }

}

运行结果