按List中对像某属性排序算法4---JAVA简单选择排序

按List中Person类的age属性进行排序。

Person类：

package com.flg;

/**
 * Created with IntelliJ IDEA.
 * User: fuliguo
 * Date: 12-7-29
 * Time: 下午13:09
 * To change this template use File | Settings | File Templates.
 */
public class Person {

    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public Person(){}

    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;
    }

}

MyPersonListSortTest_SimpleSelection类：

package com.flg;

import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

/**
 * 简单选择排序
 * Created with IntelliJ IDEA.
 * User: fuliguo
 * Date: 12-7-29
 * Time: 下午13:10
 * To change this template use File | Settings | File Templates.
 */
public class MyPersonListSortTest_SimpleSelection {

    /**
     * 获得要测试的list
     * @return   list
     */
    public List getList(){

        List list  = new ArrayList<Person>() ;
        Random random = new Random();
        int j;
       /*
       for(int i=0;i<10;i++){
           j = 1+Math.abs(random.nextInt()%29); //30以内随机数
             //System.out.println("随机数-->>"+j);
             list.add(new Person("张"+j,j));  //年龄随机增长

       }
       */

        list.add(new Person("张6",6));
        list.add(new Person("张9",9));
        list.add(new Person("张12",12));
        list.add(new Person("张18",18));
        list.add(new Person("张16",16));
        list.add(new Person("张20",20));
        list.add(new Person("张3",3));
        list.add(new Person("张27",27));
        list.add(new Person("张30",30));
        list.add(new Person("张30",30));


        return list;

    }

    /**
     * 控制台输出遍历list对像顺序
     * @param list
     */
    public  void printList(List list) {
        Person p;
        for(int i=0;i<list.size();i++){
            p = (Person)list.get(i);
            System.out.println(p.getName()+"---"+p.getAge());
        }

    }

    private void swap(List list,int i,int j){

                Person p1 = (Person)list.get(i);
                Person p2 = (Person)list.get(j);

                list.set(i,p2);
                list.set(j,p1);

    }
    /**
     * 对list进行排序:简单选择排序
     *
     * 简单选择排序就是通过n-i次比较，从n-i+1个记录中选出最小的记录，
     * 并和第i（1<=i<=n）个记录交换
     * 和冒泡相比，减少了比较次数
     * 比较次数为:n-1+n-2+...1=n(n-1)/2次
     *
     * @param list
     */
    public void listSort1(List<Person> list,boolean isAsc){

               int comparaCount = 0;//统计比较次数
               int swapCount = 0;//统计交换次数

               Person p1,p2;
               int i,j,min;

               for( i=0;i<list.size();i++){

                   min = i;

                   for( j=i+1;j<list.size()-1;j++){
                       p1 = (Person)list.get(min);
                       p2 = (Person)list.get(j);

                       comparaCount ++;//统计比较次数
                       if(!(isAsc^(p1.getAge()>p2.getAge()))){ //非运算，非真即假
                          min = j;
                       }
                   }

                   if(i!=min){
                       swap(list,i,min);//i和min位置上的对象交换
                       swapCount++;//统计交换次数
                   }
               }
        //若使用统计比较数comparaCount和统计交换次数swapCount
        //要改成固定方式生成对象，针对同一组对象进行比较，
        // 否则随机生成，前后没有可比性
        System.out.println("listSort1===>comparaCount:"+comparaCount+"||swapCount:"+swapCount);
    }




    public static void main(String [] args) throws InvocationTargetException, IllegalAccessException {

        MyPersonListSortTest_SimpleSelection m = new MyPersonListSortTest_SimpleSelection();

        //排序isAsc:true 升序，false:降序
        boolean  isAsc = true;

        List list = m.getList();
        System.out.println("==========排序前=========");
        m.printList(m.getList());

        
        m.listSort1(list, isAsc); //排序isAsc:true 升序，false:降序
        System.out.println("listSort1==========排序后=========");
        m.printList(list);



    }
}

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