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  1.  
  2. import java.util.Comparator;
  3. import java.util.Optional;
  4.  
  5. public class Main {
  6.  
  7. 	public static void main(String[] args) {
  8.  
  9. 		SampleHeroes heroes = new SampleHeroes(
  10. 			new Hero("鈴木", 10),
  11. 			new Hero("佐藤", 30),
  12. 			new Hero("斎藤", 20)
  13. 		);
  14.  
  15. 		Optional<Hero> hopt = heroes.stream().max((x,y)->x.hp-y.hp);
  16.  
  17. 		if(hopt.isPresent()) {
  18. 			System.out.println("最大HPの勇者は" + hopt.get().name);
  19. 		}
  20. 	}
  21. }
  22.  
  23. //
  24. // ほんとはきっと java.util.List<Hero>
  25. //
  26. class SampleHeroes {
  27.  
  28. 	private final Hero[] heroes;
  29.  
  30. 	public SampleHeroes(Hero... heroes) {
  31.  
  32. 		this.heroes = heroes;
  33. 	}
  34.  
  35. 	//
  36. 	// heroes.stream()
  37. 	//
  38. 	SampleStream stream() {
  39.  
  40. 		return new SampleStream(heroes);
  41. 	}
  42. }
  43.  
  44. //
  45. // ほんとはきっと java.util.stream.Stream<Hero>
  46. //
  47. class SampleStream {
  48.  
  49. 	private final Hero[] heroes;
  50.  
  51. 	SampleStream(Hero[] heroes) {
  52.  
  53. 		this.heroes = heroes;
  54. 	}
  55.  
  56. 	//
  57. 	// heroes.stream().max()
  58. 	//
  59. 	public Optional<Hero> max(Comparator<Hero> comp) {
  60.  
  61. 		Hero max = heroes[0];
  62.  
  63. 		for (int i = 1; i < heroes.length; i ++) {
  64.  
  65. 			// (x,y) -> x.hp - y.hp で大小比較
  66. 			if (comp.compare(heroes[i], max) > 0) {
  67. 				max = heroes[i];
  68. 			}
  69. 		}
  70.  
  71. 		return Optional.of(max);
  72. 	}
  73. }
  74.  
  75. class Hero {
  76.  
  77. 	final String name;
  78. 	final int hp;
  79.  
  80. 	Hero(String name, int hp) {
  81.  
  82. 		this.name = name;
  83. 		this.hp   = hp;
  84. 	}
  85. }
  86.  
Success #stdin #stdout 0.17s 57468KB
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stdout 
最大HPの勇者は佐藤
https://ideone.com/17vmci
language:
Java (HotSpot 12)
created:
1 year ago
visibility:
secret

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