Question

I have a very simple Java class:

public class Party {
    private List<String> hosts = new ArrayList<String>();
    private String headHost = null;

    public void addHost(String name) {
        hosts.add(name);
        headHost = name;
    }
}

But it seems a bit silly to maintain a String keeping track of the list’s pointer…

1. Is there a better way for keeping track of who is the “head host”?

It won’t always be the last person added, either:

public void setHost(int i) {
    headHost = hosts.get(i); // potentially throws an exception based on i
}

public void setHost(String name) {
    headHost = name;
}

2. What’s the best way to change the current “head host”? Both of these methods could potentially take incorrect parameters.

Answer 1

The current version is just fine. If you are concerned about exceptions, you can apply some defensive programming to the code:

public void setHost(int i) {
    if(i < 0 || i > hosts.size()-1){
         throw new IllegalArgumentException("Index is out of range!");
    }
    headHost = hosts.get(i);
}

public void setHost(String name) {
    if(!hosts.contains(name){
         throw new IllegalArgumentException("The specified host does not exist.");
    }
    headHost = name;
}