Java Coding Problems

189. Grouping

Let's assume that we have the following Melon class and List of Melon:

public class Melon {  enum Sugar {    LOW, MEDIUM, HIGH, UNKNOWN  }  private final String type;  private final int weight;  private final Sugar sugar;  // constructors, getters, setters, equals(),  // hashCode(), toString() omitted for brevity}List<Melon> melons = Arrays.asList(  new Melon("Crenshaw", 1200),  new Melon("Gac", 3000), new Melon("Hemi", 2600),  new Melon("Hemi", 1600), new Melon("Gac", 1200),  new Melon("Apollo", 2600), new Melon("Horned", 1700),  new Melon("Gac", 3000), new Melon("Hemi", 2600));

The Java Stream API exposes the same functionality as the SQL GROUP BY clause via Collectors.groupingBy().

While the SQL GROUP BY clause works on database tables, ...