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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. import java.util.Comparator;
  8.  
  9. class ComplexComparator implements Comparator<Book> {
  10.  
  11.     private Comparator<Book> comp;
  12.  
  13.     public ComplexComparator(Comparator<Book> x, Comparator<Book> y) {
  14.         comp = x.thenComparing(y);
  15.     }
  16.  
  17.     public ComplexComparator(Comparator<Book> x, boolean h, Comparator<Book> y, boolean i) {
  18.         if (h && i) {
  19.             comp = x.thenComparing(y);
  20.         } else if (h) {
  21.             comp = x.thenComparing(y.reversed());
  22.         } else if (i) {
  23.             comp = x.reversed().thenComparing(y);
  24.         } else {
  25.             comp = x.reversed().thenComparing(y.reversed());
  26.         }
  27.     }
  28.  
  29.     public static void main(String[] args) {
  30.         Comparator<Book> page = Comparator.comparing(Book::getPageNb);
  31.         Comparator<Book> title = Comparator.comparing(Book::getTitle);
  32.         Comparator<Book> aver = Comparator.comparing(Book::getAverage);
  33.  
  34.         ComplexComparator c1 = new ComplexComparator(page, title);
  35.         ComplexComparator c2 = new ComplexComparator(page, false, title, true);
  36.         ComplexComparator c3 = new ComplexComparator(aver, false, title, true);
  37.  
  38.         Book b1 = new Book(5, "abc", 10);
  39.         Book b2 = new Book(10, "abc", 10);
  40.         System.out.println(c1.compare(b1, b2)); // -1, page only
  41.         System.out.println(c2.compare(b1, b2)); //  1, page only reversed
  42.         System.out.println(c3.compare(b1, b2)); //  0, same page&title
  43.     }
  44.  
  45.     @Override
  46.     public int compare(Book o1, Book o2) {
  47.         return comp.compare(o1, o2);
  48.     }
  49. }
  50.  
  51. class Book {
  52.     int pageNb;
  53.     String title;
  54.     int average;
  55.  
  56.     public Book(int pageNb, String title, int average) {
  57.         this.pageNb = pageNb;
  58.         this.title = title;
  59.         this.average = average;
  60.     }
  61.  
  62.     public int getPageNb() { return pageNb;  }
  63.     public String getTitle() { return title;  }
  64.     public int getAverage() { return average;  }
  65. }
Success #stdin #stdout 0.15s 33828KB
comments (?)
stdin 
Standard input is empty
stdout 
-1
1
0
https://ideone.com/CEBl0z
language:
Java (HotSpot 12)
created:
7 years ago
visibility:
public

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