package com.test;
import Java.util.*;
Emp.java文件如下：
class Emp{
 private String empNo ;
 private String empName ;
 private float sal ;
 public String getEmpNo() {
  return empNo;
 }
 public void setEmpNo(String empNo) {
  this.empNo = empNo;
 }
 public String getEmpName() {
  return empName;
 }
 public void setEmpName(String empName) {
  this.empName = empName;
 }
 public float getSal() {
  return sal;
 }
 public void setSal(float sal) {
  this.sal = sal;
 }
 public Emp(String empNo,String empName,float sal){
  this.empNo = empNo ;
  this.empName = empName ;
  this.sal = sal ;
 }
}

class MyComparator implements Comparator{
 public int compare(Object o1,Object o2) {
  Emp e1=(Emp)o1;
  Emp e2=(Emp)o2;
  if(e1.getSal()<e2.getSal()) 
  return 1; else 
  return 0;
 }
}

public class Test {
 /** 
* @param args 
*/
 public static void main(String[] args) {
  // TODO Auto-generated method stub 
  ArrayList al = new ArrayList() ;
  Emp emp1 = new Emp("sn001","ysj1",2500) ;
  Emp emp2 = new Emp("sn002","ysj2",1200) ;
  Emp emp3 = new Emp("sn003","ysj3",8900) ;
  Emp emp4 = new Emp("sn004","ysj4",3400) ;
  Emp emp5 = new Emp("sn005","ysj5",4500) ;
  al.add(emp1) ;
  al.add(emp2) ;
  al.add(emp3) ;
  al.add(emp4) ;
  al.add(emp5) ;
  System.out.println("排序前的值");
  for (int i=0;i<al.size();i++){
   Emp emp = (Emp)al.get(i) ;
   System.out.println(emp.getSal());
  }
  //必须是Comparator中的compare方法和Collections.sort方法配合使用才管用 
  MyComparator mc = new MyComparator() ;
  Collections.sort(al, mc) ;
  System.out.println("排序后的值");
  for (int i=0;i<al.size();i++){
   Emp emp = (Emp)al.get(i) ;
   System.out.println(emp.getSal());
  }
 }
}