使用Java Stream根据第二个列表中的值筛选列表

Question

我正在尝试根据第二个列表中的值筛选对象列表。

[
   {
      "id":"12345",
      "name":"nameOfItem",
      "description":"descriptionOfItem"
   },
   {
      "id":"34567",
      "name":"nameOfItem",
      "description":"descriptionOfItem"
   },
   {
      "id":"56789",
      "name":"nameOfItem",
      "description":"descriptionOfItem"
   }
]

["12345", "56789"]

现在我想移除列表A的项目，该项目的ID在列表B中可用。

null

null

            if let allModOptions = allModifersList?.first?.options {
                let excludedIDs = pObj?.excluded_ids
                if excludedIDs!.count > 0 {
                   let allowedOptions = allModOptions
                   ->>>>    **.filter{ !excludedIDs!.contains($0.id!)}** <<<<-
                        .filter{c in c.deleted_at == nil}.sorted {
                        $0.index ?? 0 < $1.index ?? 0
                       }
                
                    allModsList?.first?.options = allowedOptions
                
                }
               modisList.append(contentsOf: allModsList!)
            }

感谢任何帮助

Answer 1

您应该在主集合上使用filter，在列表集合上使用！contains

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

class Scratch {
    static class Element {
        int id;
        String name;
        String description;

        public Element(int id, String name, String description) {
            this.id = id;
            this.name = name;
            this.description = description;
        }

        @Override
        public String toString() {
            return "Element{" +
                    "id=" + id +
                    ", name='" + name + '\'' +
                    ", description='" + description + '\'' +
                    '}';
        }
    }

    public static void main(String[] args) {
        List<Element> elements = new ArrayList<>(Arrays.asList(
           new Element(12345, "nameofitem", "asdfafd"),
           new Element(34567, "nameofitem", "asdfafd"),
           new Element(56789, "nameofitem", "asdfafd")
        ));
        List<Integer> filterNot = new ArrayList<>(Arrays.asList(12345, 56789));
        List<Element> result = elements.stream().filter(item -> !filterNot.contains(item.id)).collect(Collectors.toList());

        result.forEach(System.out::println);
    }


}