Problem in showing value of a string object of jsp to on page

hello there
i have a problem that i m fatching a value from a JavaBean in my jsp page now i want to print that value in my jsp page but i is createing problem
my probelm is that the value which i have been fatching from my javabean contain code like
#include<stdio.h>
#include<conio.h>
void main
int a=10;
printf("%d",a);
getch();
i m getting this code in a variable in a String object myCode
and when i m displaying this using
<%=myCode%>
it is giving output as follows
#include<stdio.h> #include<conio.h> void main { int a=10; printf("%d",a);
getch();}
can you tell me why it is creating a problem
plz help me
thanks in advance
pawan gupta

HTML formats in its own special way. It ignores spaces/newlines.
Try using <pre> tags to tell the browser "this is pre-formatted text. Don't screw around with it"
ie
<pre><%= myCode %></pre>
Cheers,
evnafets

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Hi,
Let me describe a basic scenario in which my problem occurs. I have a backing bean and a JSP. The JSP gets a List<String> which is displayed inside a column in an editable HtmlDataTable. Each row in the data table has a UICommandLink that can perform an update to the value in the first column. Hence, the table only has two columns: one input field and one command link.
My problem is this: When I try to execute HtmlDataTable#getRowData() when the command link is pressed, the updated values are not retrieved, but instead the values that have been in the input field before any changes were made. However, if I instead wrap my List objects inside a StringWrapper class (with a String property and appropriate getters and setters) such that I have a List<StringWrapper>, the problem does not occur. Why is this and is there any way to avoid it?
I typed out some code to illustrate my scenario. Example 1 is where the table displays a list of String objects and Example 2 is where the table displays a list of StringWrapper objects.
Example 1: [http://pastebin.com/m2ec5d122|http://pastebin.com/m2ec5d122]
Example 2: [http://pastebin.com/d4e8c3fa3|http://pastebin.com/d4e8c3fa3]
I'll appreciate any feedback, many thanks!

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

why jvm maintains string pool only for string objects why not for other objects? why there is no pool for other objects? what is the specialty of string?

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.
Please refer these links
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

String object vs String literal

Hi ,
I understand how the string objects are created using new operator and using literal.I also understand how they are stored in memory.All I want to know is that when and why should I create a String object using new and when I should create an object using literal.Is there any specific reason for creating an object using new operator when objects created by both the ways are immutable.
Thanks for the help in advance.
Thanks
Mouli

If you look at the String source code (particularly the constructors) youll learn a lot.
String objects contain a char[] array - and this is the most important part --> a start and length value.
I believe they were attempting to optimize, but this has important implications for developers.
String objects dont necessarily store just the text you see, it may just reference a much bigger char array.
For example, say an API passes you a string that is (lets pretend) a file path (C:\files\java\...\file.txt) that is 1,000,000 characters long.
Now say that you call getFileName() and want to save the filename in a list.
String filename = API.getFile("...").getFileName();
List.add(filename);
Say you do this about 250,000 times.
You estimate that the average file name is 10 chars and ensure there is that much RAM.
You run out of memory. Why?
Well, this example actually happened to me in a real program I was writing to archive drive files.
File.getFilename() returns a substring() of the entire File path.
However, substring is implemented to return a String that just references the original char[] array!
So the really long file path never gets garbage collected!
I was able to fix the program by coding it:
String filename = new String(API.getFile("...").getFileName()); // Copies only the needed chars!
List.add(filename);
So thats really all you need to watch out for. If memory is a concern in your program you want to
make sure you arent referencing large char[] arrays unnecessarily.
But like all things, this is rarely anything to give much thought to.
Only something to remember if you run into problems after coding sensibly and profiling
(or in my case, crashing with OOM exceptions, lol).

Problem in showing value of a string object of jsp to on page

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