putExtra treeMap returns HashMap cannot be cast to TreeMap android

Question

I need your help, I cannot understand what\'s happening?

I\'m trying to send a TreeMap between 2 activities, the code is something like this:

class O         


        

Answer 1

As alternative to @Jave's suggestions, if you really need the data structure to be a TreeMap, just use the appropriate constructor that takes another map as data source. So on the receiving end (Two) do something like:

public class Two extends Activity {
    @Override public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        TreeMap<String, String> map = new TreeMap<String, String>((Map<String, String>) getIntent().getExtras().get("map"));
    }
}

However, depending on your project, you probably don't have to worry about the exact Map implementation. So in stead, you could just cast to the Map interface:

public class Two extends Activity {
    @Override public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Map<String, String> map = (Map<String, String>) getIntent().getExtras().get("map");
    }
}

Answer 2

Sounds like it serializes to a HashMap and that's what you're getting. Guess you're gonna have to settle for a HashMap. Alternatively you can create your own helper class and implement Parcelable, then serialize the key/strings in order.

Answer 3

Instead of casting the result directly to a TreeMap, you can create a new TreeMap<String, String> and use the putAll()-method:

TreeMap<String, String> myMap = new TreeMap<String, String>;
HashMap<String, String> receivedMap = getIntent().getExtras().get("map");
myMap.putAll(receivedMap);