Static Initialization and still null pointer exception

Question

I followed advice on constructing a static hashmap from other SO posts, but now I am having a null pointed exception when I try to access the information in the HashMap. Any ideas?

public final class EMUtil {
static private HashMap<String,TreeSet<String>> EMGroups;
static{
    HashMap<String,TreeSet<String>> EMGroups = new HashMap<String, TreeSet<String>>();

    TreeSet<String> temp=new TreeSet<String>();
    temp.addAll(returnArray("99201","99202","99203","99204","99205"));
    EMGroups.put("Set 1",temp);

    temp=new TreeSet<String>();
    temp.addAll(returnArray("99211","99212","99213","99214","99215"));
    EMGroups.put("Set 2",temp);

    ...
}

static public boolean isEM(String curCPT){
    if((curCPT.compareTo("99200")>0)&&(curCPT.compareTo("99311")<0)){
        for(TreeSet<String> value:EMGroups.values()){
            if(value.contains(curCPT)){
                return true;
            }
        }
    }
    return false;
}

Any ideas what is going on? If I am trying to have a group of sets that I access to check if a String is in a group within that set / which group it is in are there better ways to structure this?

You're shadowing your `EMGroups` variable in the static initializer. — Alexis C., Apr 27 '15 at 16:45
You have two different variables named EMGroups. One is a static member of the class which you never use anywhere, and the other is a local variable of the static block. Within the static block, the local variable shadows the field. — Solomon Slow, Apr 27 '15 at 16:54
My fault there. I had tried to use a temporary "aMap" as shown in the accepted answer in http://stackoverflow.com/questions/507602/how-can-i-initialize-a-static-map. I was getting an ExceptionInInitializerError trying to run that, and somewhere in the middle I must have tried to undo work and created the copy. — mrfish, Apr 27 '15 at 16:57

score 3 · Answer 1 · edited Apr 27 '15 at 16:47

3

static{
    HashMap<String,TreeSet<String>> EMGroups = new HashMap<String, TreeSet<String>>();

This variable declaration is hiding your static EMGroups class member. Should be:

static{
    EMUtil.EMGroups = new HashMap<String, TreeSet<String>>();

Though you can actually drop the 'EMUtil.'

edited Apr 27 '15 at 16:47

Solomon Slow

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answered Apr 27 '15 at 16:45

ControlAltDel

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Static Initialization and still null pointer exception

1 Answers1