What was the effect of japan's self-imposed isolation?

There were both negative and positive effects of Japan's self-imposed isolation. 

Negative effect: They were closed off from the world. They did not trade, this meant they had limited exotic resources. 

Positive effect: They were safe. Since they were closed off from the rest of the world, they didn't have as many threats to their region (until later on). 

I hope this helps!