Groupby and Collect Example
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package com.javabullets;
// {
import java.time.Duration;
import java.util.*;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.*;
public class WinnersGroupby {
// }
public void winnersGroupby() {
// groupingby - make a map whose keys are names
Map<String, List<Winner>> namesVsWinner = com.javabullets.Winner.tdfWinners
.stream()
.collect(groupingBy(Winner::getName));
// namesVsWinner - {Bradley Wiggins=[Bradley Wiggins], Carlos Sastre=[Carlos Sastre], Cadel Evans=[Cadel Evans], Óscar Pereiro=[Óscar Pereiro], Chris Froome=[Chris Froome, Chris Froome, Chris Froome], Andy Schleck=[Andy Schleck], Alberto Contador=[Alberto Contador, Alberto Contador], Vincenzo Nibali=[Vincenzo Nibali]}
System.out.println("namesVsWinner - " + namesVsWinner);
// join strings
String allTDFWinnersTeamsCSV = com.javabullets.Winner.tdfWinners
.stream()
.map(Winner::getTeam)
.collect(joining(", "));
// allTDFWinnersTeams Caisse d'Epargne–Illes Balears, Discovery Channel, Team CSC, Astana, Team Saxo Bank, BMC Racing Team, Team Sky, Team Sky, Astana, Team Sky, Team Sky
System.out.println("allTDFWinnersTeams " + allTDFWinnersTeamsCSV);
}
// {
}
// }
Press desired key combination and then press ENTER.
