What is the difference between += and =+?

Question

What is the difference between += and =+? Specifically, in java, but in general also.

Answer 1

i += 4;

means

i = i + 4;  // increase i by 4.

While

i =+ 4;

is equivalent to

i = +4;   // assign 4 to i. the unary plus is effectively no-op.

(See http://docs.oracle.com/javase/specs/jls/se7/html/jls-15.html#jls-15.15.3 for what a unary + does.)