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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.util.stream.Collectors;
  7.  
  8. /* Name of the class has to be "Main" only if the class is public. */
  9. class Ideone
  10. {
  11.  
  12. 	private static final class Inner {
  13.  
  14. 		public Inner(String id, int type) {
  15. 			setId(id); setType(type);
  16. 		}
  17.  
  18. 		String id;
  19. 		String getId() { return id;}
  20. 		void setId(String id) { this.id=id; }
  21. 		int type;
  22. 		int getType() { return type; }
  23. 		void setType(int type) { this.type = type; }
  24. 	}
  25.  
  26. 	public static void main (String[] args) throws java.lang.Exception {
  27. 		ArrayList<Inner> list = new ArrayList<>();
  28. 		list.add(new Inner("1", 2));
  29. 		list.add(new Inner("2", 3));
  30. 		list.add(new Inner("3", 3));
  31. 		list.add(new Inner("4", 3));
  32. 		list.add(new Inner("5", 2));
  33. 		list.add(new Inner("6", 1));
  34. 		// 1 item of type 1, 2 of type 2 and 3 of type 3, so the expected result is {1=1, 2=2, 3=3}
  35. 		System.out.println(list.stream().collect(
  36. 			Collectors.groupingBy(Inner::getType, Collectors.counting())
  37. 		));
  38. 	}
  39. }
Success #stdin #stdout 0.14s 2184192KB
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Standard input is empty
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{1=1, 2=2, 3=3}
https://ideone.com/rLIBuP
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
public

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