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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. import java.text.*;
  7.  
  8. /* Name of the class has to be "Main" only if the class is public. */
  9. class Ideone
  10. {
  11. 	private static class MyObject {
  12. 		private Date date;
  13. 		private int price;
  14. 		private int quality;
  15.  
  16. 		MyObject(Date date, int price, int quality) {
  17. 			this.date = date;
  18. 			this.price = price;
  19. 			this.quality = quality;
  20. 		}
  21.  
  22. 		public Date getDate() {
  23. 			return date;
  24. 		}
  25.  
  26. 		public int getPrice() {
  27. 			return price;
  28. 		}
  29.  
  30. 		public int getQuality() {
  31. 			return quality;
  32. 		}
  33.  
  34. 		@Override
  35. 		public String toString() {
  36. 			Format sdf = new SimpleDateFormat("dd/MM/yyyy");
  37. 			return "MyObject[" + sdf.format(date) + ", " + price + ", " + quality + "]";
  38. 		}
  39. 	}
  40.  
  41. 	private static class MyObjectComparator implements Comparator<Object> {
  42.  
  43. 	    private String getter;
  44.  
  45. 	    public MyObjectComparator(String field) {
  46. 	        this.getter = "get" + field.substring(0, 1).toUpperCase() + field.substring(1);
  47. 	    }
  48.  
  49. 	    @Override
  50. 	    public int compare(Object o1, Object o2) {
  51. 	        try {
  52. 	            if (o1 != null && o2 != null) {
  53. 	                o1 = o1.getClass().getMethod(getter, new Class[0]).invoke(o1, new Object[0]);
  54. 	                o2 = o2.getClass().getMethod(getter, new Class[0]).invoke(o2, new Object[0]);
  55. 	            }
  56. 	        } catch (Exception e) {
  57. 	            throw new RuntimeException("Cannot compare " + o1 + " with " + o2 + " on " + getter, e);
  58. 	        }
  59.  
  60. 	        return (o1 == null) ? -1 : ((o2 == null) ? 1 : ((Comparable<Object>) o1).compareTo(o2));
  61. 	    }
  62. 	}
  63.  
  64. 	public static void main (String[] args) throws java.lang.Exception
  65. 	{
  66. 		SimpleDateFormat sdf = new SimpleDateFormat("dd/MM/yyyy");
  67. 		List<MyObject> objs = new ArrayList<>();
  68. 		objs.add(new MyObject(sdf.parse("21/12/2015"), 1234, 2));
  69. 		objs.add(new MyObject(sdf.parse("12/01/2016"), 134, 4));
  70. 		objs.add(new MyObject(sdf.parse("01/01/2012"), 3244, 1));
  71.  
  72. 		System.out.println("Сортировка по качеству:");
  73. 		Collections.sort(objs, new MyObjectComparator("quality"));
  74. 		System.out.println(objs);
  75.  
  76. 		System.out.println("Сортировка по цене:");
  77. 		Collections.sort(objs, new MyObjectComparator("price"));
  78. 		System.out.println(objs);
  79.  
  80. 		System.out.println("Сортировка по дате:");
  81. 		Collections.sort(objs, new MyObjectComparator("date"));
  82. 		System.out.println(objs);
  83. 	}
  84. }
Success #stdin #stdout 0.15s 321280KB
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Сортировка по качеству:
[MyObject[01/01/2012, 3244, 1], MyObject[21/12/2015, 1234, 2], MyObject[12/01/2016, 134, 4]]
Сортировка по цене:
[MyObject[12/01/2016, 134, 4], MyObject[21/12/2015, 1234, 2], MyObject[01/01/2012, 3244, 1]]
Сортировка по дате:
[MyObject[01/01/2012, 3244, 1], MyObject[21/12/2015, 1234, 2], MyObject[12/01/2016, 134, 4]]
https://ideone.com/1Ydqaw
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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