What is the purpose of using "+=" instead of "=" in java? -

so ran piece of code today while working on existing codebase. question why assignment operator not used here.

  int getsum(int mvar) {       int sum = 0;       sum += ((mvar != null) ? mvar : 0);       return sum;     } 

it appears assignment operator suffice:

int getsum(int mvar) {       int sum = ((mvar != null) ? mvar : 0);       return sum;     } 

is there benefit initializing value zero?

to answer question, in example there no point in using "+=", regular assignment operator better

 int getsum(int mvar) {       int sum = 0;       sum += ((mvar != null) ? mvar : 0);       return sum;  } 

this code bad example of "+=" because shouldn't used here. instead should be:

   int getsum(integer mvar) {           return mvar != null? mvar : 0;    } 

you don't see benefit of "+=" because sum 0. so, @ , you're wondering why sum = 0 + mvar; (which same saying sum += mvar when can sum = mvar;

a better example (ofc these values don't make sense, makes "+=" valuable):

  int getsum(int mvar) {           int sum = 5;           sum += ((mvar != null) ? mvar : 10);           return sum;      } 

this way if don't use "+=" forced in saying sum = sum + mvar; or else wouldn't correct.