使用比较器对列表进行排序不起作用

Question

I want to sort list of product data on the basis of axis type count.I am not able to find the issue in below code . How can i sort this result?

private void sortResults(List<ProductData> results) {
        Collections.sort(results, new Comparator<ProductData>() {
            @Override
            public int compare(ProductData product1, ProductData product2) {
                return product1.getAxisTypeCount().compareTo(product2.getAxisTypeCount());
            }
        });}


ProductSearchPageData<SearchStateData, ProductData> searchPageData = null;
            searchPageData = encodeSearchPageData(productSearchFacade.textSearch(searchState, pageableData));
sortResults(searchPageData.getResults());

The expected result: Makeup 37 , Watches 7 , jewelry 6 , skincare 6, Fragrance 4

The actual result: Makeup 37 , Fragrance 4 , jewelry 6 , skincare 6,Watches 7

Answer 1

private void sortResults(List<ProductData> results) {
    Collections.sort(results, new Comparator<ProductData>() {
        @Override
        public int compare(ProductData product1, ProductData product2) {
            return product1.getAxisTypeCount().compareTo(product2.getAxisTypeCount());
        }
    });}

product1 would take second value from the list, whereas product2 will take first value from the list. For instance:

Your list is [Watches , jewelry, Fragrance, .........] On calling compare function product1 = jewelry and product2 = Watches

I am assuming getAxisTypeCount() is giving integer value, if your object is "Makeup 37", getAxisTypeCount() would return 37

This line =>

return product1.getAxisTypeCount().compareTo(product2.getAxisTypeCount());

would result:

Fragrance   4
jewelry   6
skincare   6
Watches   7
Makeup   37

not as you mentioned in the actual result Makeup 37 , Fragrance 4 , jewelry 6 , skincare 6, Watches 7

If you want your compare method should result output as you mentioned in expected result: Makeup 37 , Watches 7 , jewelry 6 , skincare 6, Fragrance 4

This line return product2.getAxisTypeCount().compareTo(product1.getAxisTypeCount()) will solve you problem.

private void sortResults(List<ProductData> results) {
    Collections.sort(results, new Comparator<ProductData>() {
        @Override
        public int compare(ProductData product1, ProductData product2) {
            return product2.getAxisTypeCount().compareTo(product1.getAxisTypeCount());
        }
    });}