packagecn.demo;

import org.apache.commons.collections.CollectionUtils;

import java.util.ArrayList;

import java.util.List;

/**

* @author Administrator

* @date 2020/7/31

*/

public class GrowthRateDemo {

/**

* 初始化数据

* @return

*/

public static List getPerson(){

List list=new ArrayList<>();

PersonInfo personInfo=new PersonInfo();

personInfo.setCountNumber(100);

personInfo.setCreateTime("2016");

PersonInfo personInfo2=new PersonInfo();

personInfo2.setCountNumber(450);

personInfo2.setCreateTime("2017");

PersonInfo personInfo4=new PersonInfo();

personInfo4.setCountNumber(22);

personInfo4.setCreateTime("2018");

PersonInfo personInfo5=new PersonInfo();

personInfo5.setCountNumber(100);

personInfo5.setCreateTime("2019");

PersonInfo personInfo6=new PersonInfo();

personInfo6.setCountNumber(200);

personInfo6.setCreateTime("2020");

list.add(personInfo);

list.add(personInfo2);

list.add(personInfo4);

list.add(personInfo5);

list.add(personInfo6);

return list;

}

/**

* 计算年度增长率

*

* 以年度分组

*

* 增长率: (a-b)b*100+'%' =》(前面的数字-后面的数字)/后面的数字*100

*/

public static List getAnalysisData(){

List result =new ArrayList<>();

List person2 =new ArrayList<>();

List person0=new ArrayList<>();

List person = getPerson();

//第1项

PersonInfo personInfo0 = person.get(0);

personInfo0.setGrowthRate("0%");

person0.add(personInfo0);

//第一项不做比较

if (CollectionUtils.isNotEmpty(person)){

for (int i = 1; i < person.size(); i++) {

PersonInfo personInfo=new PersonInfo();

Integer countNumber = person.get(i).getCountNumber();

Integer countNumber1 = person.get(i - 1).getCountNumber();

if (countNumber

//如果下个数大于上个数，则增长率 为 正

String growthRate=(countNumber1-countNumber)/countNumber*100+"%";

personInfo.setGrowthRate("-"+growthRate);

}else if (countNumber>countNumber1){

//如果下个数小于上个数，则增长率 为 负

String growthRate= (countNumber-countNumber1)/countNumber1*100+"%";

personInfo.setGrowthRate(growthRate);

}else{

//如果相等，增长率为 0

personInfo.setGrowthRate("0%");

}

personInfo.setCountNumber(person.get(i).getCountNumber());

personInfo.setCreateTime(person.get(i).getCreateTime());

person2.add(personInfo);

}

}

//list合并

result.addAll(person0);

result.addAll(person2);

return result;

}

public static void main(String[] args) {

List analysisData = getAnalysisData();

if (CollectionUtils.isNotEmpty(analysisData)){

analysisData.stream().forEach(item->{

System.out.println("数量:"+item.getCountNumber());

System.out.println("增长率:"+item.getGrowthRate());

System.out.println("时间:"+item.getCreateTime());

System.out.println("*****************************************************");

});

}

}

}