Java for C++ and Python Developers

Snippet 1: NullPointerException ! Java tries to unbox null to int , which is impossible.
Snippet 2: Every iteration unboxes sum to int , adds i , then boxes the result back to Integer — creating a new object each time. Use int sum = 0 instead.

Delete saved progress?

Do you want to delete all saved progress for this tutorial and reset the current step files?

Selecting No will just turn off auto-save — your progress is kept but won't be updated.

Reading aloud 1.0x