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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. /* Name of the class has to be "Main" only if the class is public. */
  8. class Ideone
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12.  
  13.         Map < String, Set < String > > map =
  14.                 Map.of(
  15.                         "laptops" , Set.of( "macbook" , "thinkpad" , "yoga" ) ,
  16.                         "desktops" , Set.of( "macmini" , "imac" , "otherDesktop" ) ,
  17.                         "smartphones" , Set.of( "iphone" , "galaxy5" , "oneplus" )
  18.                 );
  19.  
  20.         // You said: dictionary.get("macbook") would return "laptops"
  21.         Optional < Map.Entry < String, Set < String > > > entry =
  22.                 map
  23.                         .entrySet()
  24.                         .stream()
  25.                         .filter( ( Map.Entry < String, Set < String > > stringSetEntry ) -> stringSetEntry.getValue().contains( "macbook" ) )
  26.                         .findAny();
  27.         String result = entry.get().getKey();
  28.         System.out.println( "result = " + result );
  29.  
  30.  
  31. 	}
  32. }
Success #stdin #stdout 0.14s 50428KB
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Standard input is empty
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result = laptops
https://ideone.com/nTzR47
language:
Java (HotSpot 12)
created:
3 years ago
visibility:
public

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