Cast Object to Map<?,?> without Unchecked cast warning

Question

I am working on a project that requires passing around objects, what I am trying to do, is turn that object back into a Map like so.

Object o = new Map<String, String>();
Map<String,String> map = (Map<String,String>)o;

This seems to work as expected, but I am getting a

Type safety: Unchecked cast from Object to Map

I know that I could use @SuppressWarnings("unchecked") , but I would prefer to do it in a way that I don't have a warning. How would this be done?

Answer 1

You can check, if o is a Map with o instanceof Map . But you can't check the Generic Arguments <String,String> , since they're erased at runtime. So even with the instanceof check you'll get a warning.

Answer 2

Since Map extends Object , you can just use a Map reference instead of downcasting to Object .

So in your code, simply replace

Object o = new Map<String, String>();

with

Map<String, String> o = new Map<>();

And then your second line (with the unchecked cast) becomes unnecessary.