Requirement Overview

A recent client request required implementing multi-column sorting for a list query.

Analysis Approach

Given the manageable data volume, direct retrieval followed by in-memory sorting using Collections.sort was deemed appropriate.

Implementation Strategy

The solution involved creating a custom comparator to handle complex sorting logic. The apprroach utilized a dedicated sorting class that could process multiple criteria based on specified parameters.

public class MultiColumnSorter implements Comparator<StockComparisonVO> {
    private String orderDirection;
    
    public MultiColumnSorter() {}
    
    public MultiColumnSorter(String direction) {
        this.orderDirection = direction;
    }
    
    @Override
    public int compare(StockComparisonVO item1, StockComparisonVO item2) {
        int diff1 = item1.getStockDifference() != null ? 
                   item1.getStockDifference().intValue() : 0;
        int diff2 = item2.getStockDifference() != null ? 
                   item2.getStockDifference().intValue() : 0;
        
        diff1 = Math.abs(diff1);
        diff2 = Math.abs(diff2);
        
        if ("desc".equals(orderDirection)) {
            if (diff1 == 0 && diff2 == 0) {
                if (item1.getCompanyStock() != null && item2.getCompanyStock() != null) {
                    return item2.getCompanyStock().compareTo(item1.getCompanyStock());
                } else if (item1.getCustomsTheoreticalStock() != null && 
                          item2.getCustomsTheoreticalStock() != null) {
                    return item2.getCustomsTheoreticalStock().compareTo(
                        item1.getCustomsTheoreticalStock());
                }
                return 1;
            } else {
                return diff2 - diff1;
            }
        } else if ("asc".equals(orderDirection)) {
            if (diff1 == 0 && diff2 == 0) {
                if (item1.getCompanyStock() != null && item2.getCompanyStock() != null) {
                    return item1.getCompanyStock().compareTo(item2.getCompanyStock());
                } else if (item1.getCustomsTheoreticalStock() != null && 
                          item2.getCustomsTheoreticalStock() != null) {
                    return item1.getCustomsTheoreticalStock().compareTo(
                        item2.getCustomsTheoreticalStock());
                }
                return 1;
            } else {
                return diff1 - diff2;
            }
        } else {
            return 1;
        }
    }
}

The implementation accepts a parameter to detemrine sorting direction. Usage involves calling:

Collections.sort(dataList, new MultiColumnSorter(String.valueOf(requestParams.getOrder())));

After deployment and testing, the solution successfully handled both ascending and descending orders according to specifications.