big-model-java/slibra-common/src/main/java/com/slibra/common/DecimalUtils.java

package com.slibra.common;

import com.alibaba.fastjson2.JSON;
import com.alibaba.fastjson2.JSONArray;
import com.slibra.common.utils.StringUtils;

import java.math.BigDecimal;
import java.math.RoundingMode;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import static com.slibra.common.constant.MyConstants.INT_2;

public class DecimalUtils {


    public static BigDecimal getAbs(BigDecimal req){
        if(Objects.isNull(req))
            return null;
        return req.abs();
    }


    public static BigDecimal getAbsAndScale(BigDecimal req, int length){
        if(Objects.isNull(req))
            return null;
        return req.abs().setScale(length, RoundingMode.DOWN);
    }

    /**
     * 处理字符串类型的数值 取绝对值并保持N位小数。
     * @param req
     * @param length
     * @return
     */
    public static String getAbsAndScaleStr(String req, int length){
        if(StringUtils.isBlank(req))
            return null;
        return new BigDecimal(req).abs().setScale(length, RoundingMode.DOWN).toString();
    }

    public static String getAbsForArray(String list, int length) {
        if (StringUtils.isBlank(list)) {
            return null;
        }
        return JSONArray.parseArray(list, BigDecimal.class).stream().map(num -> getAbsAndScale(num, length)).collect(Collectors.toList()).toString();
    }


    public static void main(String[] args) {
//         System.out.println(getAbsAndScale(null, 3));
//         System.out.println(getAbsAndScale(new BigDecimal("33.33333"), 3));
//         System.out.println(getAbsAndScale(new BigDecimal("-33.33333"), 3));
//         List<Double> list = new ArrayList<>();
//         list.add(1.1D);
//         list.add(1.2D);
//         list.add(1.3D);
//         System.out.println(list.toString());
//         System.out.println(JSON.toJSONString(list));
//
// //        System.out.println(getAbsForArray("a", 1));
//
//         System.out.println(new BigDecimal(1.1).divide(new BigDecimal(1.3), 0, RoundingMode.HALF_UP));
//         System.out.println(DecimalUtils.getAbsAndScale(new BigDecimal("3486.000000"), INT_2));

        List<Integer> arr = new ArrayList<>();
        arr.add(1);
        arr.add(2);
        OptionalDouble average = arr.stream().mapToInt(Integer::intValue).average();
        System.out.println(average.getAsDouble());
    }
}