Errata-OCP Oracle Certified Professional Java SE 11 Programmer I Exam 1Z0-815 (Ch.5,Page no: 316,317

[Shankar Ghimire]

Page No: 316
String singleString = "hello world";
String oneLine = "hello " + "world";
System.out.println(singleString == oneLine);

Both print false. Concatenation is just like calling a method and
results in a new String.


Page No: 317
15: String first = "rat" + 1;
16: String second = "r" + "a" + "t" + "1";

18: System.out.println(first == second);
19: System.out.println(first == second.intern());


On line 15, we have a compile-time constant that automatically gets
placed in the string pool as "rat1". On line 16, we have a more
complicated expression that is also a compile-time constant.
Therefore, first and second share the same string pool reference. This
makes line 18 and 19 print true.

You have discussed the same topics, but the logic is quite contradictory.

[Mikalai Zaikin]

I agree, in the first code it seems that " helloworld" is compared with "hello world", which may not be true for sure 8-)
We can't consider it as an error, because false will be printed and false mentioned in the book, but probably it's a typo.
Only Authors know if it's a typo... 8-)

[Shankar Ghimire]

Mikalai Zaikin wrote:I agree, in the first code it seems that " helloworld" is compared with "hello world", which may not be true for sure 8-)
We can't consider it as an error, because false will be printed and false mentioned in the book, but probably it's a typo.
Only Authors know if it's a typo... 8-)

I'm not talking about "hello world" and "helloworld". or "hello " + "world", space after the letter 'o' in "hello ".

I am talking about the reason the author has mentioned.
"Concatenation is just like calling a method and results in a new String." on page no 316
and
"a compile-time constant that automatically gets placed in the string pool as "rat1" " on page no. 317.

On both examples, the concatenation operator '+' has been used. so, I got confused.

[Jesse Silverman]

See this recent thread:
https://coderanch.com/t/739996/certification/Java-String-compile-time-constant

It doesn't have the right book in the thread name, but I think it is the same stuff.