I am learning java and this logic makes me feel confused.

Isn't here i=20( 1) 20( 1)?

Why 41 instead of 42?

jshell> int i = 20
i ==> 20
jshell> i=i     i  
i ==> 41

See this code run at Ideone.com.

CodePudding user response：

Effectively, the expression i=i i ; is equal to i=i i;. Why? The latter i result value is never used and is not propagated. The result of the postfix addition i is used as long as the value i is added later in the expression and the result takes the effect. However, after the latter i the result value of i is not used.

If you want to achieve the result of 42, you need to perform the postfix assignment (i ) after the whole result is assigned back to the i variable:

int i = 20;
i = i     i;
i  ;
System.out.println(i);