Integer.valueOf returns ASCII against a character

Question

Integer.valueOf takes in String and int as arguments but when I pass Character, it doesn't require casting and compiler doesn't enforce anything.

Character doesn't extend String class, it just implements Serializable and Comparable

Character charc = '1';
System.out.println(Integer.valueOf(charc));
System.out.println(Integer.valueOf(charc.toString()));

output:

49
1

Isn't it kind of design flaw or I am thinking in the wrong direction? Please write the reason in comments when you down-vote it.

@DanyalSandeelo consider `Character charc = '1'; int i = charc; System.out.println(i);` - same result — Scary Wombat, Dec 16 '19 at 08:00
@ScaryWombat that will print 1 instead of 49 ... it prints 49 — Danyal Sandeelo, Dec 16 '19 at 08:02
@ScaryWombat `Character charc = '1'; System.out.println(charc); ` prints 1. I am on compiler now. — Danyal Sandeelo, Dec 16 '19 at 08:03
That is not my code - read carefully `Character -> char -> int` — Scary Wombat, Dec 16 '19 at 08:04
Have a look at https://stackoverflow.com/questions/46343616/how-can-i-convert-a-char-to-int-in-java/46343671 — , Dec 16 '19 at 08:05
@ScaryWombat got it.. so basically it's converting the Character to char and then it auto converts it into `int` which is why it prints 49 — Danyal Sandeelo, Dec 16 '19 at 08:06

score 5 · Answer 1 · answered Dec 16 '19 at 08:17

This is specifically covered by JLS 5.2, Assignment conversion. (Passing a parameter to a method is essentially like assigning a value to a variable.)

Assignment contexts allow the use of one of the following:

...

an unboxing conversion (§5.1.8) optionally followed by a widening primitive conversion.

What's happening here is that the Character is being unboxed to char; and then the char is being widened to int.

score 2 · Accepted Answer · edited Dec 16 '19 at 08:10

2

The char ist auto-widened to an int, which is a perfectly valid parameter for Integer.valueOf()

Java converts some types automatically if the required type contains all of the current type like char to int or int to long. See the Java Language Specification for details.

edited Dec 16 '19 at 08:10

Danyal Sandeelo

12,196
10
47
78

answered Dec 16 '19 at 08:06

Nicktar

5,548
1
28
43

Integer.valueOf returns ASCII against a character

2 Answers2