[java] HashMap(key: String, value: ArrayList) returns an Object instead of ArrayList?

I'm storing data in a HashMap with (key: String, value: ArrayList). The part I'm having trouble with declares a new ArrayList "current," searches the HashMap for the String "dictCode," and if found sets current as the returned value ArrayList.

ArrayList current = new ArrayList();      
if(dictMap.containsKey(dictCode)) {
    current = dictMap.get(dictCode);   
}

The "current =..." line returns a compiler error of:

Error: incompatible types
found   : java.lang.Object
required: java.util.ArrayList

I don't understand this... does that HashMap return an Object instead of the ArrayList I stored in it as the value? How do I convert this object into an ArrayList?

Thank you.

I suppose your dictMap is of type HashMap, which makes it default to HashMap<Object, Object>. If you want it to be more specific, declare it as HashMap<String, ArrayList>, or even better, as HashMap<String, ArrayList<T>>

Using generics (as in the above answers) is your best bet here. I've just double checked and:

test.put("test", arraylistone); 
ArrayList current = new ArrayList();
current = (ArrayList) test.get("test");

will work as well, through I wouldn't recommend it as the generics ensure that only the correct data is added, rather than trying to do the handling at retrieval time.

public static void main(String arg[])
{
    HashMap<String, ArrayList<String>> hashmap = 
        new HashMap<String, ArrayList<String>>();
    ArrayList<String> arraylist = new ArrayList<String>();
    arraylist.add("Hello");
    arraylist.add("World.");
    hashmap.put("my key", arraylist);
    arraylist = hashmap.get("not inserted");
    System.out.println(arraylist);
    arraylist = hashmap.get("my key");
    System.out.println(arraylist);
}

null
[Hello, World.]

Works fine... maybe you find your mistake in my code.

The get method of the HashMap is returning an Object, but the variable current is expected to take a ArrayList:

ArrayList current = new ArrayList();
// ...
current = dictMap.get(dictCode);

For the above code to work, the Object must be cast to an ArrayList:

ArrayList current = new ArrayList();
// ...
current = (ArrayList)dictMap.get(dictCode);

However, probably the better way would be to use generic collection objects in the first place:

HashMap<String, ArrayList<Object>> dictMap =
    new HashMap<String, ArrayList<Object>>();

// Populate the HashMap.

ArrayList<Object> current = new ArrayList<Object>();      
if(dictMap.containsKey(dictCode)) {
    current = dictMap.get(dictCode);   
}

The above code is assuming that the ArrayList has a list of Objects, and that should be changed as necessary.

For more information on generics, The Java Tutorials has a lesson on generics.