java 计算年增长率 案例

计算年度增长率：

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

package cn.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<PersonInfo>  getPerson(){
        List<PersonInfo> 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
     * <p>
     *  以年度分组
     *  <p>
     *  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<PersonInfo> getAnalysisData(){
        List<PersonInfo> result =new ArrayList<>();
        List<PersonInfo> person2 =new ArrayList<>();
        List<PersonInfo> person0=new ArrayList<>();

        List<PersonInfo> 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<countNumber1){
                    //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<PersonInfo> 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("*****************************************************");
            });
        }
    }
}

 

工具类

package cn.demo;

import java.math.BigDecimal;

/**
 * 求增长率
 */
public class GrowthRate {
    public String percentBigDecimal(BigDecimal preNum, BigDecimal sufNum){
        double result = countDecimal(preNum,sufNum);
        if(result>0){
            return "+"+result+"%";
        }
        if(result<0){
            return result+"%";
        }
        if(result==0){
            return "+"+0+"%";
        }
        return null;
    }
    public  double countDecimal(BigDecimal preNum,BigDecimal sufNum){
        boolean preBoolean = verifyNum(preNum);
        boolean sufBoolean = verifyNum(sufNum);
        //同时为true计算
        if(preBoolean && sufBoolean){
            boolean b = verifyEqual(preNum, sufNum);
            if (b == false){
                return realCountDecimal(preNum,sufNum);
            }
            if (b){
                return 0;
            }
        }
        if(preBoolean == false && sufBoolean ==false){
            return 0;
        }
        if(sufBoolean ==false){
            return 100;
        }
        return  0;
    }
    //验证数字是否为零和null
    public boolean verifyNum(BigDecimal num){
        if(null !=num && num.compareTo(BigDecimal.ZERO)!=0 ){
            return true;
        }
        return false;
    }

    //验证两个数字是否相等
    public boolean verifyEqual(BigDecimal preNum,BigDecimal sufNum){
        int n = preNum.compareTo(sufNum);
        //比较 -1 小于   0 等于    1 大于
        if(n==0){
            return true;
        }
        return false;
    }
    //真正计算
    public double realCountDecimal(BigDecimal preNum,BigDecimal sufNum){
        //(前面的数字-后面的数字)/后面的数字*100
        BigDecimal bigDecimal = (preNum.subtract(sufNum)).divide(sufNum).multiply(new BigDecimal("100")).setScale(2, BigDecimal.ROUND_UP);
        if (bigDecimal.compareTo(BigDecimal.ZERO) !=0){
            return  bigDecimal.doubleValue();
        }
        return 0;
    }

    public static void main(String[] args) {
        GrowthRate p = new GrowthRate();
        BigDecimal a = new BigDecimal("3");
        BigDecimal b = new BigDecimal("2");
        String percent = p.percentBigDecimal(a, b);
        System.out.println(percent);
    }

}