How to cast an object to a HashMap?

Question

HashMap myMap = (HashMap) getLastNonConfigurationInstance();

myMap is always null. getLastNonConfigurationInstance() returns an object. My map has two keys "symbol" and "name".

public Object onRetainNonConfigurationInstance()
    {
        HashMap myMap = new HashMap();
        myMap.put("symbol", this.symbol);
        final Object data = myMap;
        return data;
    }

Answer 1

If getLastNonConfigurationInstance() returns a non-null object, then (HashMap) getLastNonConfigurationInstance() will either return the same object (if that object is a HashMap), or throw a ClassCastException.

The situation that you describe is not possible, not unless you've uncovered a long-hidden bug in Java's cast operator. Hint: you haven't.

Verify that getLastNonConfigurationInstance() is actually returning a non-null object. Verify that myMap is actually null. If you're using a debugger to check those values, try printing them to the console instead. Debuggers can lie to you sometimes, or at least mislead.

Answer 2

You haven't told us in what situation this happens? onRetainNonConfigurationInstance() is called before an Activity's onDestroy() when a configuration change happens.