随机产生10个学生，按ID大小排列

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Random;
import java.util.Comparator;

 

public class Test4 {

 public static void main(String[] args) {
  Random ran=new Random();
  List list=new ArrayList();

  for(int i=0;i<10;i++){
   Student s=new Student();
   s.setId(i+1);
   s.setName(createName());
   s.setAge(ran.nextInt(6)+15);
   list.add(s);
  }

  Collections.sort(list,new StudentComparator());
  /*for(int i=0;i<list.size()-1;i++){

   for(int j=i+1;j<list.size();j++){
    Student s1=(Student)list.get(i);
    Student s2=(Student)list.get(j);
    int age1=s1.getAge();
    int age2=s2.getAge();

    if(age1>age2){

     //list.set(i, s2);
     //list.set(j, s1);
     Collections.swap(list, i, j);

    }
   }

  }*///也可以这样排序

  for(int i=0;i<list.size();i++){

   Student s=(Student)list.get(i);

   System.out.println(s);

  }

 }

 public static String createName(){
  Random ran=new Random();
  int len=ran.nextInt(5)+6;
  String name="";
  for(int i=0;i<len;i++){
   name+=(char)(ran.nextInt(26)+'a');
  }
  return name;
 }
}

class Student {

 private int id;
 private String name;
 private int age;
 public int getId() {
  return id;
 }
 public void setId(int id) {
  this.id = id;
 }
 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;
 }

 @Override
 public String toString() {

  return id+"\t"+name+"\t"+age;
 }
 @Override
 public int hashCode() {
  final int prime = 31;
  int result = 1;
  result = prime * result + age;
  result = prime * result + id;
  result = prime * result + ((name == null) ? 0 : name.hashCode());
  return result;
 }
 @Override
 public boolean equals(Object obj) {
  if (this == obj)
   return true;
  if (obj == null)
   return false;
  if (getClass() != obj.getClass())
   return false;
  Student other = (Student) obj;
  if (age != other.age)
   return false;
  if (id != other.id)
   return false;
  if (name == null) {
   if (other.name != null)
    return false;
  } else if (!name.equals(other.name))
   return false;
  return true;
 }

}

class StudentComparator implements Comparator{

 public int compare(Object o1, Object o2) {
  Student s1=(Student)o1;
  Student s2=(Student)o2;
  return s1.getAge()-s2.getAge();
 }

}

 

打印结果：

7 joziywjc 15
9 sqclbqoqpv 15
3 qkpxii 16
4 rsoohwbx 16
8 skjolpg 16
1 swzkdmjh 17
10 vdvpxdu 17
2 awsjwwqneq 18
5 gfiashjeyb 19
6 evjlfdqfrt 19