HashMap updating ArrayList

You could use something like:

mMap.get("A").add("test");
mMap.get("B").add("entry");

1. Like @Tudor said, use mMap.get("A").add("foo");

2. You put the same exact list into each map entry. You initial lines should be

    mMap.put("A", new ArrayList());
    mMap.put("B", new ArrayList()); 
    ...
    mMap.put("Z", new ArrayList());

Alternatvely, write a method that checks on the fly

public synchronized void myAdd(String key, String value) {
   List<String> there = mMap.get(key);
   if (there == null) {
      there = new ArrayList<String>();
      mMap.put(key, there);
   }
   there.add(value);
}

you probably mean:

HashMap<String, List<String>> mMap = new HashMap<String, List<String>>();
    mMap.put("A", new ArrayList<String>());
    mMap.put("B", new ArrayList<String>());
    mMap.put("C", new ArrayList<String>());
    mMap.put("D", new ArrayList<String>());

    if (mMap.containsKey("A"))
    {   
        mMap.get("A").add("test");
        System.out.println(mEntry.getKey() + " : " + mEntry.getValue());
    }
    else if (mMap.containsKey("B"))
    {   
        mMap.get("B").add("entry");
        System.out.println(mEntry.getKey() + " : " + mEntry.getValue());
    }
   ...

I wonder if you really need those containsKey checks either! HTH!