how to execute mongo admin command from java

I want to execute soem admin command with parameters from java.

The commands are:

{ enablesharding : "test" }
{ shardcollection : "test.test_collection", key : {"number":1} }

How can I do it from java driver?

The following code doesn't works:

mongo.getDb("admin").command("{shardcollection : \"test.test_collection\", key:\"number\":1} }")