Question

I’ve got a Dictionary<int BossID, string BossName> ListOfBosses and Dictionary<String EmpName, int BossID> ListOfEmps . Of course, Match the BossID to the Boss and return ‘Dictionary WhoIsMyBoss’.

I have no idea where to start in Java.

As far as the two lists go, we’ll assume there is going be a one to many ratio of Bosses to Emps. And the BossIDs are incremental from 1-n.

I figure I would do the following in my illiterate Java. . .

Dictionary<BossName, EmpName> WhoIsMyBoss;
ArrayList<Integer> AnotherListOfBosses;
private int Boss;
for (String EmpName: ListOfEmps)
        Boss = ListOfEmps.get(EmpName)
        WhoIsMyBoss.put(ListofBosses(Boss) , EmpName);
        AnotherListOfBosses.add(Boss);
}
for(int Boss: AnotherListOfBosses)
{
     ListOfBosses.remove(Boss)
}

That should leave me a list of Bosses and Employees and a
a ListOfBosses with no corresponding Employees hopefully.

How does that look? Is Dictionary the correct Collection to use? Any improvements would be greatly appreciated.

Answer 1

As Kilian Foth mentioned, you should use Map instead of Dictionary. Additionally in Java the convention is to start variable names with a lowercase and classname uppercase letter.

You said that the names are strings and the IDs integers.

public class BossExample {
  // Key: Boss-ID, Value: Boss name
  private Map<Integer, String> mapOfBosses = new HashMap<Integer, String>();

  // Key: Emp name, Value: Boss-ID
  private Map<String, Integer> mapOfEmps = new HashMap<String, Integer>();

  // Constructor fills the maps
  public BossExample() {
    // ...
  }

  // Returns a mapping from Emp name to Boss name
  public Map<String, String> getEmpToBossMap() {
    final Map<String, String> empToBossMap = new HashMap<String, String>();

    // Iterate through mapOfEmps via entrySet giving you key and value 
    // at the same time
    for(Map.Entry<String, Integer> empEntry : mapOfEmps.entrySet()) {
      // Put the Emp name as key and the retrieved Boss name as a value into 
      // the result map.
      empToBossMap.put(empEntry.getKey(), mapOfBosses.get(empEntry.getValue()));
    }

    return empToBossMap;
  }
}