What checks the String pool

Hi there.
With regard to the string pool,
my book states that whenever the compiler
encounters a string literal that it will check the pool to see if
there is a matching string...
This doesn't seem right to me.
I would have imagined that the JVM would perform this operation at runtime.
Maybe I'm wrong, but I googled it and I came across some sites that indicate that
the JVM checks the string pool.
Im just wondering which is it, the JVM or the compiler.
Thanks & regards.

jverd wrote:
Both.
String s1 = "abc";
String s2 = "abc";Compiler sees the first line, looks for "abc" in the class' constant pool, doesn't find it, adds it, places reference to its position for the assignment to s1.
Compiler sees the second line, looks for "abc", finds it, places reference to its position for the assignment to s2.
At runtime, when class is loaded, VM loads class' String constant pool. When time comes to execute the above lines, the bytecode tells it which constant pool entry to reference.Great answer (No, I'm not sarcastic)

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Hi,
REGEXP_LIKE ( str
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Checking the string

How to check the presence of numerals in a String?

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Why jvm maintains string pool only for string objects why not for other objects?

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rp0428 wrote:
You might be aware of the fact that String is an immutable object, which means string object once created cannot be manipulated or modified. If we are going for such operation then we will be creating a new string out of that operation.
It's a JVM design-time decision or rather better memory management. In programming it's quite a common case that we will define string with same values multiple times and having a pool to hold these data will be much efficient. Multiple references from program point/ refer to same object/ value.
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What is Java String Pool? | JournalDev
Why String is Immutable in Java ? | Javalobby
Sorry but you are spreading FALSE information. Also, that first article is WRONG - just as OP was wrong.
This is NO SUCH THING as a 'string pool' in Java. There is a CONSTANT pool and that pool can include STRING CONSTANTS.
It has NOTHING to do with immutability - it has to do with CONSTANTS.
Just because a string is immutable does NOT mean it is a CONSTANT. And just because two strings have the exact same sequence of characters does NOT mean they use values from the constant pool.
On the other hand class String offers the .intern() method to ensure that there is only one instance of class String for a certain sequence of characters, and the JVM calls it implicitly for literal strings and compile time string concatination results.
Chapter 3. Lexical Structure
In that sense the OPs question is valid, although the OP uses wrong wording.
And the question is: what makes class Strings special so that it offers interning while other basic types don't.
I don't know the answer.
But in my opinion this is because of the hybrid nature of strings.
In Java we have primitive types (int, float, double...) and Object types (Integer, Float, Double).
The primitive types are consessons to C developers. Without primitive types you could not write simple equiations or comparisons (a = 2+3; if (a==5) ...). [autoboxing has not been there from the beginning...]
The String class is different, almost something of both. You create String literals as you do with primitives (String a = "aString") and you can concatinate strings with the '+' operator. Nevertheless each string is an object.
It should be common knowledge that strings should not be compared with '==' but because of the interning functionality this works surprisingly often.
Since strings are so easy to create and each string is an object the lack ot the interning functionality would cause heavy memory consumption. Just look at your code how often you use the same string literal within your program.
The memory problem is less important for other object types. Either because you create less equal objects of them or the benefit of pointing to the same object is less (eg. because the memory foot print of the individual objects is almost the same as the memory footpint of the references to it needed anyway).
These are my personal thoughts.
Hope this helps.
bye
TPD

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ok sorry for not being so clear :)
When having a String class, we can initialize it by doing the following:
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koneru9999 wrote:
will the pattern is helpful in my case?
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>
Hi Bibhuprasad,
I have a task to validate an employee Id. Suppose the employee Id is
E121212. Now as per the validation rule I need to check "the first letter
of the employee Id is a character and rest are numbers." How can I do this? Please reply.Everyone else has proposed REGEXP_LIKE, and while it's very powerful, it is
also very CPU intensive. You should always use Oracle's string functions
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I played around with
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Paul...
Bibhuprasad Soumyaranjan

What is the use of at-exit in mudule pool

hi
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AT EXIT-COMMAND lets you call a module before the system executes the automatic fields checks.
Automatic field checks can be avoided through AT EXIT-COMMAND, which works exactly the same way as CANCEL works from standard tool bar. In the R/3 screen, if your want to quit the processing of that particular screen without entering the mandatory fields then user can click the CANCEL button, same functionality can be incorporated in the user defined transaction by usine AT EXIT-COMMAND. This module can be called before the system executes the automatic field checks.
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What is the main use of pooled talbe and where are they use?

Hi gus:
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Moderator message - Please search before asking - post locked
Edited by: Rob Burbank on Sep 1, 2009 9:11 AM

Hi,
Table pools are special table types in the ABAP Dictionary. The data from several different tables can be stored together in a table pool or table cluster. Tables assigned to a table pool or table cluster are referred to as pooled tables or cluster tables.
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What checks the String pool

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