对arraylist中元素进行排序实例代码

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());
		}
	}
}