Enthuware

The capacity of a StringBuilder is analogous to a bucket of water. It is empty at the beginning
and fills up as you add water to it. Once it is full, you need to get a bigger bucket and transfer
the water from the smaller bucket to the bigger one.

should be

The array of a StringBuilder is analogous to a bucket of water. It is empty at the beginning
and fills up as you add water to it. Once it is full, you need to get a bigger bucket and transfer
the water from the smaller bucket to the bigger one.

?

You could say that as well. But it is explaining capacity as an abstract concept. It is implemented using an array but that is irrelevant.

Of course. I do L-O-V-E that way of explaining that concept as well. It's just that since there's (always) an initial capacity [particularly with StringBuilder()], I was wondering if any readers could possibly be confused by saying that the capacity is "empty at the beginning", whereas there would always be an array (even without elements)? However, to the book's point .... the word "analogous" was emphasized ... and it completely underscores the point. Thanks as always.

Although there's no (current) information on it, I'm still looking forward to Enthuware's 1Z0-817 sequel once I get past this current hurdle.

ok, I see your point. Will improve.
817 mock exams are still a few weeks away from release.

Correction: Although there's no (current) information on it, I'm still looking forward to Enthuware's 1Z0-817 book sequel (to 808) once I get past this current hurdle (no rush).

Username987654 wrote: ↑

Tue Jun 11, 2019 9:22 pm

Correction: Although there's no (current) information on it, I'm still looking forward to Enthuware's 1Z0-817 book sequel (to 808) once I get past this current hurdle (no rush).

Ah...there is no update on the book as of now

Thanks

Hi
Can you explain this point regarding append and insert methods to StringBuilder?

If you pass a null, the string "null" is appended to or inserted in the existing StringBuilder. No NullPointerException is thrown.

I am running code below and in both append and insert getting a compile error warning in Intellij for both

StringBuilder sb = new StringBuilder();
sb.append(null);
sb.insert(1, null);

For append:
Ambiguous method call.
append(String) and append(StringBuffer) in StringBuilder match

Insert is similar:
Ambiguous method call.
insert(int, String) and insert(int, char[]) in StringBuilder match

I am confused by this.

Please help

Many Thanks

The error that you are getting is because of ambiguity in the method call. The compiler is not able to determine which method are you trying to invoke (append(char[]) or append(CharSequence ), both can accept null.)
The point explained in this section can be observed using this code:
StringBuilder sb = new StringBuilder();
Integer s = null;
sb.append(s);
System.out.println(sb);

May be it should be made clearer.

OK many thanks I understand now - so in your example there is no ambiguity because it uses append(Object) method?

Correct.

tnx for mister deskmush, i finally understand better the topic over sting and stringbuilder especially the method chaining, cuz i got hard time understanding trough books from other authors

also thnks to BlackCat for your question, very usefull

But there is only one thing i don't get is why setting capacity for StringBuilder if it does it automatically, plus noone know the capacity of an entire html page lol

I'm pretty sure noone use capacity and just relay on the auto allocation of JVM

Best regards and tnx in advance for the answear

Glad to know our material is helpful in your preparation.

>But there is only one thing i don't get is why setting capacity for StringBuilder if it does it automatically, plus noone know the capacity of an entire html page lol
It is just a way to optimize the operation of the StringBuilder if you already know the approximate size of the final string. You are right, it is not used very often.

thankx a lot