Case 1
string = string +((char)65) + 5;
everything is treated as String but in second case
Sequence of operation performed:
string +((char)65 = stringA
stringA + 5 = stringA5
Case 2
string += ((char)65) + 5;
first right hand side is calculated means first operation will be like ((char)65) + 5
, So result of ((char)65) + 5 is 70
and after that += operation.
Sequence of operation performed:
(char)65 + 5 = 70
string + 70 = string70
Lets see 1 more example
String string = "string";
string += ((char)65) + 5 + "A";
System.out.println(string);
Output string70A
Reason
Same first right hand side is calculated and sequesce of opertion performed is
(char)65 + 5 = 70
70 + "A" = 70A
string + 70A = string70A