Question

I have a situation where I have a User that is a certain profession, so I have something like:

public abstract class Job
{
    private static String name;
    public static String getJobName() { return name; }
}

and

public class Baker extends Job
{
    // I realize this is probably wrong, but not the main point
    Baker() { name = "Baker"; }
}

Then i wanted to store the User->Profession in a map like

Map<User, Class<? extends Job>> uJobs = HashMap<User, Class<? extends Job>>();
uJobs.put(user, Baker.class); // This seems to work
String jobName = uJobs.get(user).getJobName(); // This not so much, and the IDE (eclipse) just somes 'class' specific stuff, not Job specific stuff.

Any advice is appreciated. The core goal here is to map 1 Object to a Class that I can just call static methods from without needing an instance for every Object.

Answer 1

Don’t put the class object in the hash map, just put an instance of the class.

Map<User,Job> uJobs=new HashMap<User, Job>();
uJobs.put(user, new Baker());
String jobname=uJobs.get(user).getJobName();

Better still, you probably don’t need to create a new instance of Baker each time you add a user. Make a static or a singleton.

class Baker extends Job
{
  public static Job instance=new Baker();
  public String getJobName()
  {
    return "Baker";
  }
}
...
uJobs.put(user, Baker.instance);

If the only thing that distinguishes the jobs is data, you don’t need to subclass. You could instead say

class Job
{
  public static Job BAKER=new Job("baker", 7);
  public static Job BUTCHER=new Job("butcher", 12);
  public static Job CANDLESTICK_MAKER=new Job("candlestick maker", 27);

  private String name;
  private int whateverCode;

  pubilc Job(String name, int whateverCode)
  {
    this.name=name;
    this.whateverCode=whateverCode;
  }
  public String getJobName()
  {
    return name;
  }
  public int getWhateverCode()
  {
    return whateverCode;
  }
}
...
uJob.put(user, Job.BAKER);