How do the post increment (i++) and pre increment (++i) operators work in Java?

++a increments and then uses the variable.
a++ uses and then increments the variable.

If you have

a = 1;

and you do

System.out.println(a++); //You will see 1

//Now a is 2

System.out.println(++a); //You will see 3

codaddict explains your particular snippet.


Does this help?

a = 5;
i=++a + ++a + a++; =>
i=6 + 7 + 7; (a=8)

a = 5;
i=a++ + ++a + ++a; =>
i=5 + 7 + 8; (a=8)

The main point is that ++a increments the value and immediately returns it.

a++ also increments the value (in the background) but returns unchanged value of the variable - what looks like it is executed later.


In both cases it first calculates value, but in post-increment it holds old value and after calculating returns it

++a

  1. a = a + 1;
  2. return a;

a++

  1. temp = a;
  2. a = a + 1;
  3. return temp;