What can't happen

You will not on any system see something like this:

-128
-127
-126
-125
-124
-12-128
-127
-126
-125
-128
-127
-126
-125
-1243
-122
-121
-120
-1-124
-123
...
125
126
127

It will always be the case that an entire line is or is not printed. There are no partial lines. This is because System.out.println() is thread-safe.