[数据结构与算法]java 集合多字段排序

现在遇到的排序场景是 根据集合对象中，优先按照A字段排序，A字段相等，则按照B字段排序，C字段不为空的放最后。

Collections.sort 排序的返回值 是 1 ，0 -1 其中，a.compareTo(b)==0,是 二者相等，a.compareTo(b)==1, 是 a大于b

public class Test01 {
    public static void main(String[] args) {
        List<FundBenchMarkInfo> fundBenchMarkList = new ArrayList<>();
        fundBenchMarkList.add(new FundBenchMarkInfo("2",new BigDecimal("123"),null));
        fundBenchMarkList.add(new FundBenchMarkInfo("5",new BigDecimal("12"),null));
        fundBenchMarkList.add(new FundBenchMarkInfo("1",new BigDecimal("8"),null));
        fundBenchMarkList.add(new FundBenchMarkInfo("7",new BigDecimal("8"),new BigDecimal("123345")));
        fundBenchMarkList.add(new FundBenchMarkInfo("8",new BigDecimal("3"),new BigDecimal("90")));
        fundBenchMarkList.add(new FundBenchMarkInfo("9",new BigDecimal("8"),null));
        // en_constant<>null 排最后, 排序是升序， 升序排序的规则 A对象在前，B对象在后，和入参保持一致 就是升序排序
        Collections.sort(fundBenchMarkList, new Comparator<FundBenchMarkInfo>() {
            // 按照照规则根据优先en_weight排序，如en_weight相同按指数内码排序,en_constant<>null排最后
            @Override
            public int compare(FundBenchMarkInfo me1, FundBenchMarkInfo me2) {
                int result = 0;
                if (null != me1.getEnConstant()) {
                    return -1;
                }
                if (null != me2.getEnConstant()) {
                    return -1;
                }
                if (me1.getEnWeight().compareTo(me2.getEnWeight()) == result) {
                    result = me1.getIndexScod().compareTo(me2.getIndexScod());
                } else {
                    result = me1.getEnWeight().compareTo(me2.getEnWeight());
                }
                return result;
            }
        });

        System.out.println(JSON.toJSONString(fundBenchMarkList));
    }
}

public class FundBenchMarkInfo {
    /**
     * 指数Wind代码
     */
    private String indexScod;
    /**
     * 权重
     */
    private BigDecimal enWeight;

    /**
     * 常数
     */
    private BigDecimal enConstant;

    public FundBenchMarkInfo() {
    }

    public FundBenchMarkInfo(String indexScod, BigDecimal enWeight, BigDecimal enConstant) {
        this.indexScod = indexScod;
        this.enWeight = enWeight;
        this.enConstant = enConstant;
    }

    public String getIndexScod() {
        return indexScod;
    }

    public void setIndexScod(String indexScod) {
        this.indexScod = indexScod;
    }

    public BigDecimal getEnWeight() {
        return enWeight;
    }

    public void setEnWeight(BigDecimal enWeight) {
        this.enWeight = enWeight;
    }

    public BigDecimal getEnConstant() {
        return enConstant;
    }

    public void setEnConstant(BigDecimal enConstant) {
        this.enConstant = enConstant;
    }

    @Override
    public String toString() {
        return "FundBenchMarkInfo{" +
                "indexScod='" + indexScod + '\'' +
                ", enWeight=" + enWeight +
                ", enConstant=" + enConstant +
                '}';
    }
}

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