如何在java 8

Question

我有数据点课。类定义如下：

public class ExciseReportDataPoint {
    private String liquorCategoryName;
    private String liquorName;
    private String nozzleName;
    private String bottleExciseNumber;
    private int fixedPegSize;
    private double costPerPeg;
    private int bottleSize;
    private int consumedVolumeInMl;
    private int volumeInBottleInMl;
    private boolean isBottleEmpty;
    private int totalNoOfPegsPoured;
    private double totalSaleValue;
    // Getters and setters for all

}

我从我的API获得List<ExciseReportDataPoint>。我想显示表格报告，其中行必须先用LiquorCategory然后用Liquor进行分类。

我想将List<ExciseReportDataPoint>转换为Map<String, Map <String, List<List<String>>>>。我不确定是否可以使用 stream 和收藏家

有没有人接受这个？

Answer 1

您可以多次对列表进行分组：

Map<String, Map<String, List<ExciseReportDataPoint>>> map = list.stream().collect(Collectors.groupingBy(ExciseReportDataPoint::getLiquorCategoryName, Collectors.groupingBy(ExciseReportDataPoint::getLiquorName)));