我需要符号 += 的帮助

Question

I am beginner and I want ask the meaning of this symbol:

I know that this:

i++ ------> is this i=i+1

but this:

+= -------> what is?

Do you know other rare symbols (aka operators)?

Answer 1

x+=y

is not a rare piece of notation at all. It's just a shortened version of the following:

x = x + y

Answer 2

It's just a shorter variant of base math function.

a += 5   =>   a = a + 5;
a += 1   =>   a = a + 1   =>   a++ // special case of the code abode, incrementation is allowed by this shorter code

a *= 2   =>   a = a * 2

a -= 1   =>   a = a - 1   =>   a--
a -= 2   =>   a = a - 2 

etc.

Answer 3

Some time we need to modify same variable value and reassigned it to same reference variable. Java allows you to combine assignment and addition operators using a shorthand operator . For example, the preceding statement can be written as:

i +=8; //This is same as i = i+8;

+= goes under assignment operator category like

 += -= *= /= %= &= ^= |= <<= >>= >>>=

means

+= addition and assignment operator

x +=y; as same as x= x+y;

Answer 4

i++、i=i+1 和 i+=1 都是一回事。