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  1. import java.util.*;
  2. import java.util.stream.Collectors;
  3.  
  4. public class Main {
  5.  
  6.     int i = 0;
  7.  
  8.     static class Item<T extends Comparable<T>> implements Comparable<Item<T>> {
  9.         long id;
  10.         T sortingKey;
  11.  
  12.         public Item(T key) {
  13.             this.sortingKey = key;
  14.         }
  15.  
  16.         @Override
  17.         public int compareTo(Item<T> o) {
  18.             return sortingKey.compareTo(o.sortingKey);
  19.         }
  20.     }
  21.  
  22.     public List<Long> getSortedIds(int itemType) {
  23.         if (itemType == 1) {
  24.             List<Item<Long>> items = getItems(1, Long.class);
  25.             Collections.sort(items);
  26.             return items.stream().map(it -> it.id).collect(Collectors.toList());
  27.         } else if (itemType == 2) {
  28.             List<Item<Date>> items = getItems(2, Date.class);
  29.             Collections.sort(items);
  30.             return items.stream().map(it -> it.id).collect(Collectors.toList());
  31.         }
  32.         //...
  33.         return null;
  34.     }
  35.  
  36.  
  37.     public <T extends Comparable<T>> List<Item<T>> getItems(int itemType, Class<T> cl) {
  38.         List<Item<T>> items = new ArrayList<>();
  39.  
  40.         Object valueFromDb = getFakeValueFromDb(itemType);
  41.         T casted = (T) valueFromDb;
  42.         items.add(new Item<>(casted));
  43.  
  44.         valueFromDb = getFakeValueFromDb(itemType);
  45.         casted = (T) valueFromDb;
  46.         items.add(new Item<>(casted));
  47.  
  48.         return items;
  49.     }
  50.  
  51.     private Object getFakeValueFromDb(int itemType) {
  52.         if (itemType == 1) {
  53.             return i++;
  54.         } else if (itemType == 2) {
  55.             return new Date();
  56.         }
  57.         return null;
  58.     }
  59.  
  60.     public static void main(String[] args) {
  61.         new Main().getSortedIds(1); 
  62.     }
  63. }
  64.  
Success #stdin #stdout 0.25s 33620KB
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https://ideone.com/mw3K26
language:
Java (12.0.1)
created:
7 years ago
visibility:
public

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