Filing Tax return for new immigrant

I became a US permanent resident on April 17, just 1 day before the tax file deadline for the year 2015 (Deadline is April 18). Do I need to file a tax return even though I was not a US resident in the year of 2015?
 
Then you were a nonresident alien for all of 2015. Nonresident aliens are only subject to US taxes for US income. If you didn't have any US income, you don't have to file a US tax return.
 
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