| instanceOf operator new bie question |
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- 1
- JTabel and JScrollPane doens't scrollHello,
I have a problem with a larger table.
I have a JTable whiches model contains 38 columns.
I put this Table in a JScrollPane. But on the screen there is no
scrollbar but a table with 38 very small columns.
I thought there must be a scroll bar for horizontal scrolling instead.
Are there any traps in this?
kind regards
Falko
- 1
- Clipboard doesn't see changes to the system-clipboard...I have an signed Applet with a JTable, where I have implemented
"cut & paste" to/from the system clipboard.
(The applet is signed to get access to the system clipboard).
Everything works as expected; Copying a row from ie. Excel,
and pasting it into a JTable row, or the other way around.
But... After I do a "local" copy/paste, that is, copy a row from
my JTable, and pasting it into another row, the Applet doesn't see
changes to the system-clipboard anymore. If I after this copy a new
row out of Excel, and try to paste it into my Applet table, what I get
is the old data from my last "local" copy-paste operation.
Anyone seen this behaviour before?
Any hints?
TIA...
- 4
- short circuit operatorsOn Feb 25, 5:19 pm, Patricia Shanahan <email***@***.com> wrote:
> k-e-n wrote:
>
> ...
>
> > Also as I mention in the list below it is simply not good practice to
> > mix Bitwise and Boolean operators in the same expression, just because
> > you can, does not mean you should.
> ...
> > 3. And I think most important of all: Do Not Mix Boolean Operators and
> > Bitwise Operators in the Same Expression.
>
> Note that "|" and "&" with boolean operands, such as true and false, are
> not bitwise operations. They are boolean operations without
> short-circuiting, so that the right hand side is evaluated regardless of
> the left hand side value. They are only bitwise operators if applied to
> integer operands.
>
> What is wrong with mixing bitwise and boolean operators in the same
> expression? Suppose I want to do something if a particular bit is on in
> either of two ints:
>
> if( (intA & mask) || (intB & mask) )
>
> seems reasonable to me, but it definitely mixes bitwise and boolean
> operations. How would you do it?
>
> Patricia
I would do it as you have done and as Joshua Cranmer suggests, use
parenthesis to make the precedence and more specifically your intent
clear.
To a programmer the parenthesis are sufficient advice, to someone who
seems not to understand precedence or perhaps more specifically wants
to know why the rule(s)
exists and what is the meta-rule behind that, I felt something
stronger was required.
Did you have any problem with any other parts of my comment? I have no
wish to cause offense or create any controversy.
- 6
- What Collection to use?Dear all,
My app can load files using a FileChooser. I would like to store the
last 4 loaded file pathes so I can use them later (ie fast access to
last used files). I'm looking for the perfect Collection to store these
4 File objects.
I think it should have the following properties
1. no duplicate objects
2. knowing the insert order (so you know which was last entered)
3. limited size (4 objects) and throwing out the oldest entry when
inserting a new one (like a ring buffer maybe)
Is there such a Collection already or do I have to homecook one?
Thanks for your answers
Phil
PS: Is there a summary table on the web with all properties of the
standard subclasses of Collection and Map?
- 6
- StreamCorruptedExceptionHi
sorry my english is not very good [:())
i have something like that:
Socket------------------------------------------------class1------ObjectOutp
utStream
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inner class in class1-thread-ObjectInputSt.
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-----------------class2
| |
| inner class in class2 thread ObjectInputStream,
ObjectOutputStream
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--------class3- and here when i create ObjectOutputStream in inner class in
class1 in thread
jumps out exception StreamCorruptedException
why?
please help
i don't know what i have should do?
Czeski
- 6
- Java In A Nutshell, 5th Edition moreWith more than 700,000 copies sold to date, Java in a Nutshell from
O'Reilly is clearly the favorite resource amongst the legion of
developers and programmers using Java technology. And now, with the
release of the 5.0 version of Java, O'Reilly has given the book that
defined the "in a Nutshell" category another impressive tune-up.
In this latest revision, readers will find Java in a Nutshell, 5th
Edition does more than just cover the extensive changes implicit in
5.0, the newest version of Java. It's undergone a complete makeover--in
scope, size, and type of coverage--in order to more closely meet the
needs of the modern Java programmer.
more http://www.cdbook.cn/book.asp?id=676
- 10
- JSP codeHi,
I have the following code
<html>
<head>
<title>
Authentication
</title>
</head>
<body>
<%!
private String username = null;
private String password = null;
private boolean completeLoginInformation=true;
%>
<%
username = request.getParameter("username");
password = request.getParameter("password");
%>
<H2><p>Checking authentication...</p></H2>
<%
if (username == null)
{ completeLoginInformation = false;
%><p><H3>Username has been left empty...</H3></p>
<% } %>
<%
if (password == null)
{ completeLoginInformation = false;
%><p><H3>Password has been left empty...</H3></p>
<% } %>
<% if (completeLoginInformation == false) { %>
<p><a href="http://localhost:8080/jsp-examples/cal/Front.jsp">Return
back to Front Page</a></p>
<p><a href="http://localhost:8080/jsp-examples/cal/AdminLog.jsp">Return
back to Administration Authentication</a></p>
<% } else { %>
<p>Need to search in database</p>
<p>All data has been entered</p>
<% } %>
</body>
</html>
Now when username and password arguments are given as empty, the flag
is supposed to be set free and in the web browser shows me the 2 links
given. Instead, the else part is being given.
Can someone help me out
Thanks in Advance
- 12
- Job for the Position of Project Lead in a MNC at BangaloreCompany Profile :
The company is an ISO 9001:2000 Quality certified company, is in the
business of providing world-class software solutions and support
services to its clients. Located in Bangalore. They provide IT
services across various domains such as Insurance, Financial Services,
Travel, Retail, and Logistics etc. They have been building customized
applications that have robust layers of application architecture.
Job Profile :
Incumbent should have hands on in Core Java, MVC Architecture, Design
Patterns,J2EE, Struts,EJB, MySQL
Must have knowledge of APEX.
Should have min 6 yrs of exp
Should have good oral and written communication and good analytical
skills
Job location: Bangalore
Salary wont be a constraint for the right candidate.
If you are interested..send me your updated resume as soon as
possible email***@***.com
- 12
- Problems in printing an IntegerHamvil ha scritto:
> 1) why I get the blank page instead of the usual exception in the jsp
> page?
Ok, I've fixed this (it was a problem with the configuration of the
logger
> 2) why the variable cannot be printed?
In the logger i get the following message:
javax.servlet.jsp.JspException: Cannot find message resources under key
org.apache.struts.action.MESSAGE
What I do not understand is why struts looks for a key in the resources
file. It should just print the integer. Am I missing somethink?
BTW if I add the following in the struts-config the problem look fixed.
Is this the right approach?
<message-resources
parameter="MyWebAppResources"
null="false" />
Thanks
- 12
- JDK1.5 with JbossGreetings,
I want to try and work with some EJB3 stuff for a small website hosted on a
FreeBSD 5.4 server and was wondering at the state of JDK1.5 port and if it
is ok to use it with Jboss under FreeBSD.
Thanks
John
- 14
- Many to Many CMR with an attributeHi,
I have a db scheme where i have a Many to Many relation but i have to
store an attribute in the mapping table. Then, i thought i could
transform my N-N relation in two 1-N relation, explicitely creating the
mapping table with my own attribute but this table has no primary key
(actually it should be the composition of the two foreign keys). Is it
possible to create an Entity where primary keys is the composition of 2
CMR fields or is there another way to do something like that ?
The db :
Supplier(id, name, ...) <-*--(quantity)--*-> Item(id, name, ..)
which is actually
Supplier(id, name, ...) <-1--*-> Supplier_Item(sup_id, item_id,
quantity) <-*--1-> Item(id, name, ...)
Thanks.
- 14
- create a new windows (xp) service that runs a jar fileHello guys,
Does anyone has experience/know how to create a new windows (xp)
service that runs a jar file? This issue rises as i need to hide the
most of the java implementation in this project before it goes live.
So the idea is, to have control on the exceution of the jar from
windows windows service console (which the users can define the startup
type i.e. manual, automatic, disabled and the running life cycle i.e.
start, stop, pause, resume, restart...).
so any leads to solving this will be appreciated.
Thanks in advance. Have a nice day!
- 14
- copying Image to system clipboardHi
As far as I can tell this is not possible to copy an Image to the
system clipboard with java at the moment. However I need it for a
project I'm working on. Has anyone found any hacks to make this
possible? Also, are there any chances that this feature will be
incorporated into the JDK at some point in the future? Are plans in the
offing?
Thanks for any advice.
Michael
- 15
- do XML/XSD validation with Ant 1.5.4 and JDK 1.4.2. How?Buried somewhere in the documentation for the 1.4 JDK is a statement that
the included XML parser class cannot do schema validation (DTD validation:
yes, Schema validation: no). However, I believe that Ant uses the XML
parser in its ANT_HOME/lib directory. You probably have an older xerxes.jar
and the your best bet is to delete that and download the latest xerces.jar
and drop it into the ANT_HOME/lib directory.
<email***@***.com> wrote in message
news:email***@***.com...
> I really need to be able to validate XML against an XSD, using Ant
> 1.5.4 and JDK 1.4.2. It appears this is straightforward to do with the
> latest Ant release and/or the latest JDK, but not with the releases
> that I'm limited to.
>
> I noticed the "iso-relax" sourceforge project, which includes the JARV
> library (which contains the Ant task). This was promising, but it
> causes an NPE to be thrown in Xerces' XMLSchemaValidator class, and I
> have no idea why.
>
> I'm querying the ant-user mlist about this, but I figured this would be
> another good place to try.
>
- 15
- I really need help with this so if anyone can help me out that would be really great of you.On Feb 6, 9:12 pm, Lew <email***@***.com> wrote:
> email***@***.com wrote:
> >> Part II
>
> >> To make a profit a local store marks up the prices of its items by
> >> 25%. Write a Java program that declares the following variables:
> >> 1. a double variable named percent_markedup
> >> 2. a double variable named original_price
> >> 3. a double variable named sales_tax_rate
>
> >> In your program be sure to assign a value to each of the variables 1-3
> >> above. Use initialization for 1 and 2 and for 3.
>
> >> Using the information from above, the program should then output:
> >> 1. the original price of the item
> >> 2. the marked-up percentage of the item (original price times percent
> >> of markup)
> >> 3. the store's selling price of the item
> >> 4. the sales tax rate
> >> 5. the sales tax
> >> 6. the final price of the item (the final price of the item is the
> >> selling price plus the sales tax)
>
> >> can u send me an email or using this to communicate.
>
> Please do not use textspeak in Usenet posts.
>
> A couple of points about your assignment that you will need to know if you
> ever use Java outside of school:
>
> - by long-standing and nearly rigid convention, Java variables are spelled
> without underscores and with mixed case, capitalizing each word part except
> the first, hence "percentMarkedUp".
>
> - doubles work fine as currency values for academic work, but not so much in
> the real world. The issues are somewhat complex, so we stick with doubles
> until we've learned some more of the basics.
>
> Let's review your assignment piece by piece:
>
> >> Write a Java program
>
> I'll give you this part. A "Java program" is a class with a properly-defined
> main() method.
>
> package programming.oneohone;
> public class RetailModel
> {
> public void main( String [] args )
> {
> }
>
> }
> >> that declares the following variables
>
> There are two places you could declare variables so far, within the class
> itself as instance or class variables, or within the main() method. The
> main() method is simpler, so start there.
>
> >> 1. a double variable named percent_markedup
> >> 2. a double variable named original_price
> >> 3. a double variable named sales_tax_rate
>
> Do you know how to declare variables? I'll give you one, focusing in on just
> the main() method and not the rest of the class.
>
> public void main( String [] args )
> {
> double percent_markedup;
> }
>
> It's the same for the others.
>
> >> In your program be sure to assign a value to each of the variables 1-3
> >> above. Use initialization for 1 and 2 and for 3.
>
> Well, the declaration of 1. that I showed you doesn't assign a value, because
> it doesn't have an initialization clause.
>
> Yet.
>
> The tutorial gives a hint near the top of the page about initialization, in
> case you forget the course information:
> <http://java.sun.com/docs/books/tutorial/java/nutsandbolts/variables.html>
>
> So go ahead and modify the declarations you just wrote and add the
> initializations.
>
> Solve one itty-bitty problem at a time, and make sure your program is correct
> at each stage. Only then add in the next piece of the puzzle, one itty-bitty
> problem at a time.
>
> This is beginning to sound a lot like Patricia Shanahan's advice, isn't it?
> You should go back to her link and read it again, very carefully.
>
> Quiz: Where (in what file) do you store the source code for your RetailModel
> program?
>
> General advice: Read the rest of the tutorial, not just the one page I linked
> you to.
>
> --
> Lew
hey Lew thank you soo soo much that instruction by instruction really
helped me a lot and thank you so much again.
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Message |
dbaplusplus
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 Posted: 2006-4-28 1:52:00 |
Top |
java-programmer, instanceOf operator new bie question
I am using Java 1.4.2.x
I wrote following code:
NumberFormat df;
df = NumberFormat.getInstance();
if (df instanceof DecimalFormat) {
((DecimalFormat) df).setMinimumIntegerDigits(1);
((DecimalFormat) df).setDecimalSeparatorAlwaysShown(true);
}
What does "df instanceof DecimalFormat" really mean? Does it mean that
NumberFormat can be converted to DecimalFormat? Because my
NumberFormat.getInstance() is returning me a NumberFormat and not
DecimalFormat what else could it mean.
I did read about instanceOf opeartor on google, but it is still
confusing to me.
Thanks a lot.
Prem
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Danno
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| Posted: 2006-4-28 2:19:00 |
Top |
java-programmer >> instanceOf operator new bie question
Well, in class inheritance if one class is on the same family tree or
connected in someway to another Object or Interface, then that one
class is an instance of that relative.
In other words, if I have this class structure.....
Object
^
Fruit
________|___________
^ ^
Apple Citrus implements Squeezable
^
Orange
and lets say that I create an orange object. That means that instance
of will return true for Orange, Citrus, Squeezable, Fruit, and Object
Orange o = new Orange;
System.out.println (o instanceof Orange); //true
System.out.println (o instanceof Citrus); //true
System.out.println (o instanceof Squeezable); //true
System.out.println (o instanceof Fruit); //true
System.out.println (o instanceof Object); //true
This would be false:
System.out.println(o instanceof Apple); //false
Because that's like comparing apples to oranges...pun intended.
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dbaplusplus
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| Posted: 2006-4-28 3:07:00 |
Top |
java-programmer >> instanceOf operator new bie question
Thanks. But, it still have question:
If I wrote code like:
Fruit f = new Fruit;
Syetem.out.println(f instanceof Orange); // will that be true.
In case of DecimalFormat, it extends NumberFormat and not the other way
around.
java.text
Class DecimalFormat
java.lang.Object
java.text.Format
java.text.NumberFormat
java.text.DecimalFormat
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Arvind
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| Posted: 2006-4-28 3:19:00 |
Top |
java-programmer >> instanceOf operator new bie question
email***@***.com wrote:
> Thanks. But, it still have question:
> If I wrote code like:
> Fruit f = new Fruit;
> Syetem.out.println(f instanceof Orange); // will that be true.
Does not take long to write the snippet of code would it ? - but with
your next question the answer to this one is significant....the answer
will be false.
>
> In case of DecimalFormat, it extends NumberFormat and not the other way
> around.
>
> java.text
> Class DecimalFormat
> java.lang.Object
> java.text.Format
> java.text.NumberFormat
> java.text.DecimalFormat
Yes, DecimalForm is a concrete subclass of NumberFormat
(http://java.sun.com/j2se/1.4.2/docs/api/java/text/DecimalFormat.html)
If you read the description carefull, the getInstance() factory method
can return *any* subclass of NumberFormat - which means, when u call
the getInstance method, you can be returned a DecimalFormat, or any
other subclass.....hence the need to check whether you are really
dealing with a DecimalFormat class...
to explain it with analogy given above...
let us say, i told you, you can eat a fruit, smell a fruit, squeeze a
fruit...for all these operations on the fruit, you would not need to
know, what fruit it is - unless ofcourse, you end up trying to squeeze
a jack fruit hurting your hands ;)
But, operation like peel the fruit - would not be applicable for
strawberry, apples - but applicable for oranges - in which case, you
would need to know, whether the fruit at hand, is really an apple or an
orange before you can 'peel' it.....
hence, the use of instanceOf....
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Danno
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| Posted: 2006-4-28 3:49:00 |
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java-programmer >> instanceOf operator new bie question
Just to add, you can use
DecimalFormat df = new DecimalFormat();
or
DecimalFormat df = new DecimalFormat(pattern);
If you know you want DecimalFormat straight up.
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dbaplusplus
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| Posted: 2006-4-28 4:05:00 |
Top |
java-programmer >> instanceOf operator new bie question
I know I can use that, but some Java Documentation says. you should
not create an instance of DecimalFormat directly.
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Danno
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| Posted: 2006-4-28 4:22:00 |
Top |
java-programmer >> instanceOf operator new bie question
Yeah, it is a weird sentence too. I never quite understood the meaning
of it....
"In general, do not call the DecimalFormat constructors directly, since
the NumberFormat factory methods may return subclasses other than
DecimalFormat. "
I think they need some better documentation on this because calling
NumberFormat factory methods has nothing to do with calling
DecimalFormat constructors directly.
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Oliver Wong
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| Posted: 2006-4-29 1:04:00 |
Top |
java-programmer >> instanceOf operator new bie question
"Danno" <email***@***.com> wrote in message
news:email***@***.com...
> Yeah, it is a weird sentence too. I never quite understood the meaning
> of it....
>
> "In general, do not call the DecimalFormat constructors directly, since
> the NumberFormat factory methods may return subclasses other than
> DecimalFormat. "
>
> I think they need some better documentation on this because calling
> NumberFormat factory methods has nothing to do with calling
> DecimalFormat constructors directly.
>
What this is saying is that the "DecimalFormat" class may itself have
secret subclasses that you don't know about. E.g:
DecimalFormatSecretSubclassThatSpecializesInValuesBetweenZeroAndOne, or
DecimalFormatSecretSubclassThatSpecializesInValuesBeyond4294967296. [*]
So don't use the DecimalFormat constructor directly. Instead, use the
factory methods of NumberFormat, which will decide the best subclass to use
for the given situation and use that one.
[*] As of Java 1.5.0_06, DecimalFormat does not have any secret subclasses,
but Sun may change that in the future.
- Oliver
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Mike Schilling
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| Posted: 2006-4-29 5:02:00 |
Top |
java-programmer >> instanceOf operator new bie question
"Oliver Wong" <email***@***.com> wrote in message
news:GVr4g.196$zn1.164@edtnps90...
>
> [*] As of Java 1.5.0_06, DecimalFormat does not have any secret
> subclasses,
or if it does, they're really, really secret.
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Oliver Wong
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| Posted: 2006-5-1 23:06:00 |
Top |
java-programmer >> instanceOf operator new bie question
"Mike Schilling" <email***@***.com> wrote in message
news:5pv4g.63594$email***@***.com...
>
> "Oliver Wong" <email***@***.com> wrote in message
> news:GVr4g.196$zn1.164@edtnps90...
>>
>> [*] As of Java 1.5.0_06, DecimalFormat does not have any secret
>> subclasses,
>
> or if it does, they're really, really secret.
Right ;) I was basing my claim above by opening the JARs that Sun
bundles with the JRE, and using Eclipse to build the class hierarchy
diagram, and Eclipse says DecimalFormat has no subclasses. I also took a
peek at the getInstance() source code, and it seems to always return
DecimalFormat for now.
- Oliver
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Timo Stamm
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| Posted: 2006-5-1 23:33:00 |
Top |
java-programmer >> instanceOf operator new bie question
Oliver Wong schrieb:
>
> "Mike Schilling" <email***@***.com> wrote in message
> news:5pv4g.63594$email***@***.com...
>>
>> "Oliver Wong" <email***@***.com> wrote in message
>> news:GVr4g.196$zn1.164@edtnps90...
>>>
>>> [*] As of Java 1.5.0_06, DecimalFormat does not have any secret
>>> subclasses,
>>
>> or if it does, they're really, really secret.
>
> Right ;) I was basing my claim above by opening the JARs that Sun
> bundles with the JRE, and using Eclipse to build the class hierarchy
> diagram, and Eclipse says DecimalFormat has no subclasses. I also took a
> peek at the getInstance() source code, and it seems to always return
> DecimalFormat for now.
You can find subclasses using the java docs. Just click on "Use" to find
all dependencies, including subsclasses. Example:
http://java.sun.com/j2se/1.5.0/docs/api/java/text/class-use/NumberFormat.html
Timo
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Oliver Wong
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| Posted: 2006-5-2 0:13:00 |
Top |
java-programmer >> instanceOf operator new bie question
"Timo Stamm" <email***@***.com> wrote in message
news:44562a44$0$4499$email***@***.com...
> Oliver Wong schrieb:
>>
>> "Mike Schilling" <email***@***.com> wrote in message
>> news:5pv4g.63594$email***@***.com...
>>>
>>> "Oliver Wong" <email***@***.com> wrote in message
>>> news:GVr4g.196$zn1.164@edtnps90...
>>>>
>>>> [*] As of Java 1.5.0_06, DecimalFormat does not have any secret
>>>> subclasses,
>>>
>>> or if it does, they're really, really secret.
>>
>> Right ;) I was basing my claim above by opening the JARs that Sun
>> bundles with the JRE, and using Eclipse to build the class hierarchy
>> diagram, and Eclipse says DecimalFormat has no subclasses. I also took a
>> peek at the getInstance() source code, and it seems to always return
>> DecimalFormat for now.
>
> You can find subclasses using the java docs. Just click on "Use" to find
> all dependencies, including subsclasses. Example:
> http://java.sun.com/j2se/1.5.0/docs/api/java/text/class-use/NumberFormat.html
That would only show the publicly visible subclasses though.
- Oliver
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Mike Schilling
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| Posted: 2006-5-2 0:24:00 |
Top |
java-programmer >> instanceOf operator new bie question
"Oliver Wong" <email***@***.com> wrote in message
news:Bsq5g.2722$zn1.2089@edtnps90...
>
> "Timo Stamm" <email***@***.com> wrote in message
> news:44562a44$0$4499$email***@***.com...
>> Oliver Wong schrieb:
>>>
>>> "Mike Schilling" <email***@***.com> wrote in message
>>> news:5pv4g.63594$email***@***.com...
>>>>
>>>> "Oliver Wong" <email***@***.com> wrote in message
>>>> news:GVr4g.196$zn1.164@edtnps90...
>>>>>
>>>>> [*] As of Java 1.5.0_06, DecimalFormat does not have any secret
>>>>> subclasses,
>>>>
>>>> or if it does, they're really, really secret.
>>>
>>> Right ;) I was basing my claim above by opening the JARs that Sun
>>> bundles with the JRE, and using Eclipse to build the class hierarchy
>>> diagram, and Eclipse says DecimalFormat has no subclasses. I also took a
>>> peek at the getInstance() source code, and it seems to always return
>>> DecimalFormat for now.
>>
>> You can find subclasses using the java docs. Just click on "Use" to find
>> all dependencies, including subsclasses. Example:
>> http://java.sun.com/j2se/1.5.0/docs/api/java/text/class-use/NumberFormat.html
>
> That would only show the publicly visible subclasses though.
In fact, only *documented* publicly visible subclasses, which coulf be a
smaller set still.
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Timo Stamm
|
| Posted: 2006-5-2 0:54:00 |
Top |
java-programmer >> instanceOf operator new bie question
Mike Schilling schrieb:
> "Oliver Wong" <email***@***.com> wrote in message
> news:Bsq5g.2722$zn1.2089@edtnps90...
>> "Timo Stamm" <email***@***.com> wrote in message
>>> You can find subclasses using the java docs. Just click on "Use" to find
>>> all dependencies, including subsclasses. Example:
>>> http://java.sun.com/j2se/1.5.0/docs/api/java/text/class-use/NumberFormat.html
>> That would only show the publicly visible subclasses though.
Sorry, I didn't read the thread and missed the point.
> In fact, only *documented* publicly visible subclasses, which coulf be a
> smaller set still.
Yes, it only works with completely documented APIs like the JSE. Don't
try it on my code :)
Timo
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Chris Uppal
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| Posted: 2006-5-2 18:12:00 |
Top |
java-programmer >> instanceOf operator new bie question
Oliver Wong wrote:
> > > [*] As of Java 1.5.0_06, DecimalFormat does not have any secret
> > > subclasses,
> >
> > or if it does, they're really, really secret.
>
> Right ;) I was basing my claim above by opening the JARs that Sun
> bundles with the JRE,
Not a safe guide in general -- the platform makes use of bytecode generation in
a couple of places already[*], and who knows how far that might go...
-- chris
[*] java.lang.reflect.InvocationHandler and in the implementation of reflective
access, and possibly others I don't know about.
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Index ‹ java-programmer |
- Next
- 1
- Vmx Smalltalk for JavaA Beta version of Vmx Smalltalk for Java is now available for download.
http://vmx-net.com/downloads/downloadjvm.php
Your comments are welcome,
email***@***.com
- 2
- Generics and returning specific subclass from methodI have an abstract class called say Base and two subclasses, say Sub1 and
Sub2. Let me define a method in Super which I want to return a new instance
of the superclass itself but I want to access this without having to cast.
IE,
public class Super {
public <E extends Super> E partialCopy() {
return this; // return this for example
}
}
public class Sub1 extends Super { }
Then I want to do this without the cast.
Sub1 s1 = new Sub1();
Sub2 s2 = s1.partialCopy();
Can I do this with generics ?
- 3
- AbstractTableModel not compatible with SwingWhat happens when AbstractTableModel is no longer compatible with Swing?
I kinda see how to use it, but don't see how XMLEncoder would work in its
place.
"Warning: Serialized objects of this class will not be compatible with
future Swing releases. The current serialization support is appropriate
for short term storage or RMI between applications running the same
version of Swing. As of 1.4, support for long term storage of all
JavaBeansTM has been added to the java.beans package. Please see
XMLEncoder. "
http://java.sun.com/javase/6/docs/api/javax/swing/table/
AbstractTableModel.html
thanks,
Thufir
- 4
- jboss 4.0.3 jboss portal 2.2.1hi
i am a one week newbie to j2ee world ( no java exp )
however i am to deploy application ( that is compiere ) onto existing
platform ( pentaho that is )
as per this date my assumptions are :
= point of integration would be in portal
= compiere application itself, war, would be deployed on jboss /deploy
= jsp be made to enable access from portal to war
could somebody help me on what is the definable steps to do the
integration?
- 5
- [J2ME] UI /freezes/ after IOExceptionHi,
I have a MiDlet that starts a Thread through a Runnable, in which
there is IO activity:
Runnable runner = new Runnable() { // some IO stuff there };
Thread thd = new Thread(runner);
thd.start();
The application runs well, until I need to close the IO channels that
are opened in that separate Thread.
Of course, I catch the IOException in my Thread, and the Thread
completes properly (and dies...).
But after this catch, the UI is not responding: if I press a button the
menu will not show, and if I do some programmaticaly changes in the UI
it does not display and the call blocks (i.e. if I add an item in the
current screen, nothing happens and the next line --System.out.println--
doesn't execute).
I know the application didn't die, cause I have another Thread running a
'while' loop and printing "I am alive!" even when the UI freezes.
And also if I don't perform UI changes I can print stuff in the main Thread.
Any idea to help me ? Thank you.
--
JScoobyCed
What about a JScooby snack Shaggy ? ... Shaggy ?!
- 6
- Exec() Help!Hi,
I'm trying to start an external applet from an applet I'm writing. I know
Exec() Is the key, but I don't know how to use it. I know how to execute
external native programs (I.e. programs I have written in BASIC and
compiled). But starting an applet from an applet totally throws me. I have
tried searching the net, and that has a lot to say about executing shell
scripts, and natives - which I know how to do.
What classes do I need to import? what line of code invokes an external
applet? I don't need to grab output from the applet I want to execute, or
send input. I just want it to run.
Pleeeeeeez can anyone help, my project has to be handed in soon :-(
Thanks,
Dafydd.
- 7
- set guarded blockHow I can define, modify, delete a guarded block in NetBeans?
The gaurded block is writen by me (not by IDE).
Where is documentation about writing guarded block?
--
WOJSAL
http://www.wojsal.prv.pl
- 8
- Sun Wireless Toolkit gives SecurityException - please help.I have a midlet (not written by me), and I would like to analyze how it
works. Unfortunately I am not able to run this midlet. Everything compiles
fine but I receive an runtime exception during running sun WTK emulator.
Incorrect domain name, switching to 'untrusted'
java.lang.SecurityException: untrusted domain is not configured
at com.sun.midp.security.Permissions.forDomain(+98)
at com.sun.midp.dev.DevMIDletSuitImpl.create(+39)
at com.sun.midp.dev.DevMIDletSuitImpl.create(+62)
at com.sun.midp.main.Main.runLocalClass(+20)
at com.sun.midp.main.Main.main(+116)
Exception completed.
14945 bytecodes executed
0 thread switches
738 classes in the system (including system classes)
229 dynamic objects allocated (14588 bytes)
1 garbage collections (0 bytes coolected)
I am not able to fing any solution via google. I hav e found only some not
clear instruction to delete MIDP_HOME environment variable. But I have not
any MIDP_HOME on my system.
I have also found some advices to change something in
java.security and java.policy files.
Unforunately I don't know what to change. Anyone has any idea how to fix my
problem ??
I will be appreciate for any advice. Thanks in advance.
--
RaW
Please fill free to correct my English.
- 9
- 10
- Toward a generic Disk Sort for JavaI was thinking how you might go about writing a sort that could handle
more data than could fit in RAM. It handled the problem is Abundance
by checkpointing the app to disk to free up maximum RAM, then spawning
a copy of Opt-Tech sort. My records were roughly like DataOutputStream
would produce, so I could automatically generate the command script
sort the fields in any way I wanted.
I thought you might pull it off in Java this way.
1. You write a comparator as if you were going to sort Objects in an
ArrayList.
2. the external sort has an add method that also takes collections.
It accepts a "chunk" of records, and sorts them using Sun's sort.
Then it writes them out as SERIALISED objects in heavily buffered
stream. There may be some way to do a partial reset after each object
to speed it up.
Then you repeat collecting, sorting and writing another batch to
another file.
When you have created N files, you recycle, appending. (Optimal N to
be determined by experiment). Ideally each file would be on a
different physical drive.
Then when all the records have been added, you start merging chunks
into longer chunks, and writing out the longer chunks. Each N-way
merge cuts the number of chunks by 1/N and increases the length of the
chunks N times.
on the final merge pass does not happen until the user invokes the
Iterator to hand over the resulting records.
Another way it might be done is the records to be sorted must by byte
arrays, chunks effectively produced by DataOutputStream. You specify
offset, length and key type e.g.
int, byte, short, float, double, String.
This would require a detailed knowledge of the bit structure of the
records, the way you did in the olden days of assembler and C.
This would be clumsier to use, but would avoid the overhead of
pickling and reconstituting records on every pass.
Then of course, there is the possibility someone has already solved
this and done it well.
The universe has a sneaky habit. Problems start out small, and it
looks like a purely in RAM solution is perfectly adequate. Then they
bit by bit grow and grow and start pushing the limits of the RAM
solution. Suddenly you are faced with a major redesign.
--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com
- 11
- J2MEHello,
Are there any newsgroups or forums specifically for J2ME? I would like to
make a game for mobile devices but I don't know where to start.
Thanks in advance,
Steve
- 12
- Bug in java.net.Socket close() behavior?According to the API for java.net.Socket close():
"Any thread currently blocked in an I/O operation upon this socket
will throw a SocketException."
http://java.sun.com/j2se/1.5.0/docs/api/java/net/Socket.html#close()
I have observed that java 1.5 on FreeBSD does not follow this while
the Windows and Linux ones I have tested do. On the FreeBSD runtimes
that I have tested, a thread blocked on reading a socket just hangs
forever if the socket is closed.
Attached is a simple program that tests this behavior. It just
connects to a port on one of my servers and has a reader thread
watching input from the socket and closes the socket in a different
thread to see if the reader thread gets an exception.
Java runtimes that I have tested this on:
# java -version
java version "1.5.0"
Java(TM) 2 Runtime Environment, Standard Edition (build diablo-1.5.0-b01)
Java HotSpot(TM) 64-Bit Server VM (build diablo-1.5.0_07-b01, mixed mode)
# java -version
java version "1.5.0-p2"
Java(TM) 2 Runtime Environment, Standard Edition (build
1.5.0-p2-root_07_mar_2006_02_41)
Java HotSpot(TM) 64-Bit Server VM (build
1.5.0-p2-root_07_mar_2006_02_41, mixed mode)
- 13
- JRE installation woesHi All
I have installed the latest version of Sun's JRE on my Windows XP Pro PC.
However, its "performance" is somewhere between abysmally slow and not at
all. If I e.g. open the Java Control Panel module and click on one of the
tabs, it takes over two minutes for that tab to display - this on a 3.4 GHz
dual-processor 4 GB memory PC. Java aplications run no better. It does seem
to "speed up" if I Alt-tab to another program and then Alt-tab back.
CPU load is negligible so clearly, the JRE is waiting for something that
occurs only rarely. But I have no idea where to look.
Any help will be very much appreciated.
Ebbe
- 14
- Formatting a string in JavaHi
I am a newby in Java and am trying to format a string into a fixed
number of positions( in this case 5).
So if I have a "5" in should be "00005", and "23" should be "00023".
I hav tried looking at the classes 'import java.text.NumberFormat' and
'import java.text.Format', but I didn't get far.
Can anyone help me how I can do this in java?
Any help will be appreciated.
Regards
- 15
- Convert from text string "Hello" to floating-point number issueHi there,
My java lecturer has given us an assignment related to casting and
type conversion etc.
One of the conversions he wan't is convert "Hello" to a float.
I suspect this is a trick question on his part as "Hello" is not a
parsible value.
This is the code I have:
//Convert String object "s" to a Float object
//then convert Float object to float value
try { System.out.println("String is "+s+" float is
"+Float.valueOf(s).floatValue());
}
catch (NumberFormatException NFE)
{ System.out.println("NumberFormatException: "+ NFE.getMessage()+
" The input string does not contain a parsable number"); }
I emailed the guy but he says just to use your own judgement.
I looked at the API for the wrapper classes etc and I think a
conversion of this type is almost impossible.
Any ideas welcome.
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