Which design pattern to use for multiple Interfaces with different behaviour

Which design pattern to use for multiple Interfaces with different behaviour

I have a one Command Interface like this,
public interface ICommand{
public abstract Object execute(List<Inputs> inputs);
}
Now I have A command for other type of complex Executions so I came up
with the new Command Interface
public interface IComplexCommand {
public abstract Object execute(ComplexObjects obj);
}
I invoke the commands from the properties file which is done inside a
static initializer block of CommandFactory. My Factory method to Invoke
looks like this.
ICommand cmd= CommandFactory.getInstance().getCommand("LoopElements");
// loopElements is the key in properties file to load my
com.test.my.LoopElements class.
Now I have a issue like when I get the Command I do not want to typecase
the Command depending on Interface but I would like to have it understood
at runtime,
Can anyone please help me in better designing this. I tried to google but
I was not able to get any proper answer because the question is very
specific.