Group java string based on nth word in Camel case-CodePudding

I want to group certain java strings into subset of strings with same nth word.

Eg List:

CorePlatformPortal, CorePlatformRuntime, CorePlatformRuntimeConfiguration, DetailPageAlternative, DetailPageBooks, DetailBuild, HorizontePage, HorizontePageLogging, HorizonteBuild,

Input : 1

Output:

CorePlatformPortal, CorePlatformRuntime, CorePlatformRuntimeConfiguration || DetailPageAlternative, DetailPageBooks, DetailBuild || HorizontePage, HorizontePageLogging, HorizonteBuild

Explanation- Grouped based on Core, Detail, Horizonte

Input : 2

Output:

CorePlatformPortal, CorePlatformRuntime, CorePlatformRuntimeConfiguration || DetailPageAlternative, DetailPageBooks, HorizontePage, HorizontePageLogging || DetailBuild, HorizonteBuild

Explanation- Grouped based on Platform, Page, Build

Any leads are appreciated. Thanks

CodePudding user response：

You can make grouping using Stream API and splitting initial strings into array of words using Regexp:

List<String> list = Arrays.asList("CorePlatformPortal",
                                  "CorePlatformRuntime",
                                  "CorePlatformRuntimeConfiguration",
                                  "DetailPageAlternative",
                                  "DetailPageBooks",
                                  "DetailBuild",
                                  "HorizontePage",
                                  "HorizontePageLogging",
                                  "HorizonteBuild");
int input = 2;

Map<String, List<String>> output =  
    list.stream()
        .collect(Collectors.groupingBy(str -> str.split("(?=[A-Z])")[input-1]));

System.out.println(output);