Possible errata on p54 about Java primitives & String? (Java OCA 8 Programmer I Study Guide, Sybex)

[Juliet Smith]

3rd last paragraph on p. 54 reads:

All of the arithmetic operations may be applied to any Java primitives, except boolean and String.

Table 1.1 on p. 21 lists the Java primitive types - however String is not listed as a primitive.

Even though String is treated specially, it isn't a primitive - as far as I know

[Roel De Nijs]

Juliet Smith wrote:Table 1.1 on p. 21 lists the Java primitive types - however String is not listed as a primitive.

Even though String is treated specially, it isn't a primitive - as far as I know

You are correct! Although String literals are treated in a special way, String is definitely not a primitive. It's not listed as one of the Primitive Data Types.

Hope it helps!
Kind regards,
Roel

[Jeanne Boyarsky]

Good find. Have a cow. I've added this to the errata.

[Roel De Nijs]

Just for the record (and completeness): the + operator will work on String, but will not perform addition (like with two ints), but concatenation. So for all primitives (except boolean) the + is an arithmetic operator for addition (and that's including chars!), and for Strings it's a concatenation operator for (obviously) concatenating.

Pop quiz question time! Do you know the output of this code snippet? And "yes" or "no" is not a valid answer

String s = "java";
System.out.println(3 + 7 + s);
System.out.println(3 + s + 7);
System.out.println(s + 3 + 7);

Hope it helps!
Kind regards,
Roel