There are different ways of writing arithmetic statements.

Java Code:
i = i + 1;
i+= 1; // shortcut

i = i/2;
i /= 2;         // shortcut

i = i*2;
i *= 2;         // shortcut

i = i-1;
i -= 1;         // shortcut
It has no affect on the performance as long as left hand side variable does not require computation. If left hand side variable requires computation, then short form is ideal.

Java Code:
myArray[getCurrentndex()] = myArray[getCurrentndex()] + 1; 
// getCurrentndex() is called 2 times

myArray[getCurrentndex()] += 1;
// getCurrentndex() is called once