Must I Use Reflection?

Hi, i posted here this question, �cause it�s about DB and JDBC.
I`m coding a simple visual program, to connect with JDBC.
i have a field, who capture the path of the DB, and i need to get form there, the string:
"sun.jdbc.odbc.JdbcOdbcDriver"
must i use reflection to get it?
Or there�s another way to do this?
Thanks a lot.

Your question makes no sense.
The value you posted represents the name of a particular JDBC driver.
The string itself is a string. Nothing more. Nothing less. You can get it anywhere you can get a string from. Like a text file, a properties file, a command line option, hard coded etc. Just like you can do the same with other string values.
You certainly can't get that string from a jar file, just by itself.
No perhaps you mean the driver itself and not the string?
Then the answer is no - you can't get it from a "jar". That particular driver is a proprietary driver that only comes with the Sun VM (how it lives in the VM is irrelevant to the question.) And that is the only way you can use it. If you run your app in a Sun VM then it is always there. If it isn't a Sun VM then it isn't there.

Similar Messages

I have a annual plan, it supposed must be used in two terminals, but i haven´t been able to install any app in a second computer, it always says that the app is only available as a trial download. What can I do to solve this issue, and be able to use my p

I have a annual plan, it supposed must be used in two terminals, but i haven´t been able to install any app in a second computer, it always says that the app is only available as a trial download. What can I do to solve this issue, and be able to use my paid plan in two computers?

Hi Susan,
Please refer to the help document to fix this issue:
Creative Cloud applications unexpectedly revert to trial mode | CS6, CCM
You may also refer to the thread as below:
creative cloud software says my free trial has expired, but I have a paid subscription
Regards,
Sheena

How can i get all java class names from a package using reflection?

hi,
can i get all classes name from a package using reflection or any other way?
If possible plz give the code with example.

You can't, because the package doesn't have to be on the local machine. It could be ANYWHERE.
For example, via a URLClassLoader (ie from the internet) I could load a class called:
com.paperstack.NobodyExpectsTheSpanishInquisitionI haven't written it yet. But I might tomorrow. How are you going to determine if that class is in the package?
This subject comes up a lot. If you want to do something a bit like what you're asking for (but not quite) there are plenty of threads on the subject. Use google and/or the forum search facility to find them.
But the answer to your question, as you asked it, is "you can't do that".

I have developed a fillable form using Adobe Acrobat Pro. The form has several fields and some of the information is captured in a bar code. What programs must be used to open the form to properly fill the form out? Adobe Reader, Adobe Xi, Ibook, etc.. I

I have created a fillable form using Adobe Acrobat Pro that contains several data fields with some feeding data to a barcode in the document. I have a "button" set up to save and send the completed form one it is completed. Some of the user are having troubles filling out the form as they are using various programs to do such as iBook, Adobe Reader, etc.... Sometimes the information is not transferred to the barcode and sometimes the "submittal button" doesn't function properly.
Please provide a solution or give me a list of the programs that must be used to properly open and fill out the form.
Greatly appreciated.

Best option is to use Adobe Reader (or Acrobat, of course) on a desktop computer (ie, not on a mobile device). Any other configuration is likely to be problematic.

Calling a pkg from managed code and then using reflection to call a method from a script task

Hi we run 2012 std. I have some pretty good evidence that when I call my pkg from a .net service, a script component in that pkg fails when trying 2 use reflection to load and invoke our .net message history method. The exception is either on
the invoke or in the message history method. I suspect its in the method but will take additional steps 2 verify.
But when I run the pkg stand alone, it has no problem and the method does what it is supposed 2 do.
There r no vars passed from the service to the pkg. I wonder if its a managed to unmanaged to managed issue that the community is already aware of. If not, my apologies 4 posting this quickly.
I'll post more info here as I collect it.

we have 2 theories after showing the exception trace to folks who r more adept at managed code.
the first is related to the fact that our 3rd party dlls (I think entity framework is included in these) r older versions. I don't want to discount this theory but we have some evidence already that this might not be true.
I hope I can do justice to the 2nd theory but will make it clearer and clearer as I get a better understanding. I believe this is what Arthur was saying and I applaud his instincts. They explained that .net is so "smart" that it detected
a change in namespace (ie context as Arthur said) and purposely threw an exception 2 save us from ourselves. The workarounds discussed were a bit over my head but I will continue trying to better understand it. The fact that many of the methods
we call after reflection r now merged into one assembly seemed relevant to the discussion and possible workarounds.
this link came up in their discussion and I believe the bottom line here is that by qualifying assembly names further (in config?)r, a workaround is possible.
http://msdn.microsoft.com/en-us/library/system.type.assemblyqualifiedname(v=vs.110).aspx .
This link came up as well and has something to do with ILMerge and workarounds to ILMerge.
http://elegantcode.com/2011/04/02/dynamically-load-embedded-assemblies-because-ilmerge-appeared-to-be-out/ .
Finally, this link came up and seems to have something to do with embedding your dlls in one assembly without them losing their identity.
http://blogs.msdn.com/b/microsoft_press/archive/2010/02/03/jeffrey-richter-excerpt-2-from-clr-via-c-third-edition.aspx
I'll post more here as we muddle thru this.

XML document creation using reflection

Hi all,
I'm tyring to write a class which creates an XML document from objects passed in. For example, you call the add(Object) method and it takes your object, uses reflection, then outputs XML like this...
<fieldName>fieldValue<fieldName>
The only problem is that after looking through this forum I am a little concerned about the performance of my proposed solution (using reflection).
The class will be used in a batch process which processes millions of objects (to generate a whopping XML file that'll be sent on for further processing by a third party).
Is there a better way to do this than by using reflection?
This class is going to be used by multiple batch processes hence there will be lots of different object types passed (they'll also be new ones in the future that we don't even know about yet) hence my reflection choice.
Thanks,
Chris

The only problem is that after looking through this
forum I am a little concerned about the performance of
my proposed solution (using reflection).The only way that you'll know for sure is if you try it out. Write the code, test it, then run it in a profiler to find out where the performance problems (if any) are.
Is there a better way to do this than by using
reflection?Probably not, if you want to pass any arbitrary object to it.
One possible alternative is to have "XML aware" objects: define an interface WritesXML, that defines a method toXML(). You then check to see whether the given object implements this interface, and if it does you simply call the method, otherwise you use reflection.
Another alternative, assuming that your objects follow the Bean pattern, is to create "XML-ifiers" on the fly, similar to the way an app-server handles JSPs. First time you see an object you create a class that will write it to XML, then compile this class and invoke it for all subsequent objects. This will require that you have a JDK installed on the runtime machine, that the objects follow the Bean pattern, and that the number of instances of a given class are very high.
This class is going to be used by multiple batch
processes hence there will be lots of different object
types passed (they'll also be new ones in the future
that we don't even know about yet) hence my reflection
choice.Sounds like a good reason to use reflection.

Using reflection...

Hi,
I have one class. to run that, I am calling like the following...
java -classpath ;.;\comdotebo; com.pack1.MyClass
now I want to take the reference of this class(dynamically) using reflection pakcage like the following...
Class cla = Class.forName("com.pack1.MyClass");
but to take the class reference I need to set the classpath;
so how can i set the classpath dynamically.
please give proper solution
thanks
Raja Ramesh Kumar M

here the case is we know both the class and the class path at run time only
for ex: see the following.....
I have two files .....
1) c:\dir1\com\pack1\MyClass1.class
2) c:\dir2\com\pack2\MyClass2.class
now I want to access both the classes using reflection from ...
c:\dir3\com\pack3\MainClass.class
using reflection, we can write the following...
Class clas1 = Class.forName("com.pack1.MyClass1");
if I am taking like this, then I am getting ClassNotFoundException.
becoz, for that we have to give the proper classpath before running the program.
like.
set classpath=%classpath%;.;c:\dir1;
but my problem is here I know the the class name (for ex: com.pack1.MyClass1) and the classpath (ex: c:\dir1)
at runtime only.
so please tell me how to solve this problem
regards
Raja Ramesh Kumar

How to create an array using reflection.

How to create an array using reflection.
I want to achive something like this,Object o;
o = (Object)(new TestClass[10]);but by use of reflection.
To create a single object is simple:Object o;
o = Class.forName("TestClass").newInstance();But how do I create an array of objects, when the class of objects is known only by name? (Can't use Object[] because even though an Object[] array can be filled with "TestClass" elements only, it Cannot be casted to a TestClass[] array)
Anybody knows?":-)
Ragnvald Barth
Software enigneer

Found it!
the java.lang.reflect.Array class solves it!
Yes !!!

How To: Use reflection to create instance of generic type?

I would like to be able to use reflection to instantiate an instance of a generic type, but can't seem to avoid getting type safety warnings from the compiler. (I'm using Eclipse 3.1.1) Here is a trivial example: suppose I want to create an instance of a list of strings using reflection.
My first guess was to write the following:
Class cls = Class.forName("java.util.ArrayList<String>");
List<String> myList = cls.newInstance();The call to Class.forName throws a ClassNotFoundException. OK, fine, so I tried this:
Class cls = Class.forName("java.util.ArrayList");
List<String> myList = cls.newInstance();Now the second line generates the warning "Type safety: The expression of type List needs unchecked conversion to conform to List<String>".
If I change the second line to
List<String> myList = (List<String>)cls.newInstance();then I get the compiler warning "Type safety: The cast from Object to List<String> is actually checking against the erased type List".
This is a trivial example that illustrates my problem. What I am trying to do is to persist type-safe lists to an XML file, and then read them back in from XML into type-safe lists. When reading them back in, I don't know the type of the elements in the list until run time, so I need to use reflection to create an instance of a type-safe list.
Is this erasure business prohibiting me from doing this? Or does the reflection API provide a way for me to specify at run time the type of the elements in the list? If so, I don't see it. Is my only recourse to simply ignore the type safety warnings?

Harald,
I appreciate all your help on this topic. I think we are close to putting this thing to rest, but I'd like to run one more thing by you.
I tried something similar to your suggestion:public static <T> List<T> loadFromStorage(Class<T> clazz) {
    List<T> list = new ArrayList<T>();
    for ( ...whatever ...) {
       T obj = clazz.newInstance();
       // code to load from storage ...
       list.add(obj);
    return list;
}And everything is fine except for one small gotcha. The argument to this method is a Class<T>, and what I read from my XML storage is the fully qualified name of my class(es). As you pointed out earlier, the Class.forName("Foo") method will return a Class<?> rather than a Class<Foo>. Therefore, I am still getting a compiler warning when attempting to produce the argument to pass to the loadFromStorage method.
I was able to get around this problem and eliminate the compiler warning, but I'm not sure I like the way I did it. All of my persistent classes extend a common base class. So, I added a static Map to my base class:class Base
   private static Map<String, Class<? extends Base>> classMap = null;
   static
      Map<String, Class<? extends Base>> map = new TreeMap<String, Class<? extends Base>>();
      classMap = Collections.synchronizedMap(map);
   public static Class<? extends Base> getClass(String name)
      return classMap.get(name);
   protected static void putClass(Class<? extends Base> cls)
      classMap.put(cls.getName(), cls);
}And added a static initializer to each of my persistent classes:class Foo extends Base
   static
      Base.putClass(Foo.class);
}So now my persistence code can replace Class.forName("my.package.Foo") with Base.getClass("my.package.Foo"). Since Foo.class is of type Class<Foo>, this will give me the Class<Foo> I want instead of a Class<?>.
Basically, it works and I have no compiler warnings, but it is unfortunate that I had to come up with my own mechanism to obtain a Class<Foo> object when my starting point was the string "my.package.Foo". I think that the JDK, in order to fully support reflection with generic types, should provide a standard API for doing this. I should not have to invent my own.
Maybe it is there and I'm just not seeing it. Do you know of another way, using reflection, to get from a string "my.package.Foo" to a Class<Foo> object?
Thanks again for your help,
Gary

PL/SQL TABLE declarations must currently use binary_integer indexes

Hi,
I am having procedure written in form6i, this procedure is having pl/sql table datatyep "v_suppmesg orcl.err_message.error_tabtype;" this pl/sql datatype is defined in database and the procedure in database is not having any error in it.
But when i am compling my form its giving me error
PL/SQL TABLE declarations must currently use binary_integer indexes
and error point is *"i_rowindex"* in the sentance given below.
*"SET_GROUP_CHAR_CELL (g_suppress_error_colid, v_rowindex, v_suppmesg(i_rowindex));"*
PROCEDURE PRC_A IS
v_rowindex NUMBER (5,0) := 1;
v_suppmesg orcl.err_message.error_tabtype;
BEGIN
g_suppress_error_rgid := FIND_GROUP (g_suppress_error_rgname);
IF ID_NULL (g_suppress_error_rgid)
THEN
g_suppress_error_rgid := CREATE_GROUP (g_suppress_error_rgname, GLOBAL_SCOPE);
g_suppress_error_colid := ADD_GROUP_COLUMN ( g_suppress_error_rgid
, g_suppress_error_colname
, CHAR_COLUMN
, 15);
orcl.err_message.get_messages (v_suppmesg);
FOR i_rowindex IN 1..v_suppmesg.count
LOOP
ADD_GROUP_ROW (g_suppress_error_rgid, END_OF_GROUP);
SET_GROUP_CHAR_CELL (g_suppress_error_colid, v_rowindex, v_suppmesg(i_rowindex));
v_rowindex := v_rowindex + 1;
END LOOP;
ELSE
g_suppress_error_colid := FIND_COLUMN (g_suppress_error_rgname||'.'||g_suppress_error_colname);
END IF;
END Init_Suppress_Message;
can anyone tell me what's wrong in this.

I have the folowing compiling and executing fine (Forms 10.1.2):
DECLARE
type t1 is table of VARCHAR2(100) index by BINARY_INTEGER ;
tab t1;
rg_id RecordGroup;
gc_id GroupColumn;
BEGIN
     tab(1) := 'One' ;
     tab(2) := 'Two' ;
     tab(3) := 'Three' ;
     rg_id := FIND_GROUP ('RG10');
     IF ID_NULL (rg_id)
     THEN
          rg_id := CREATE_GROUP ('RG10', GLOBAL_SCOPE);
          gc_id := ADD_GROUP_COLUMN ( 'RG10'
          , 'COL1'
          , CHAR_COLUMN
          , 15);
          --orcl.err_message.get_messages (v_suppmesg);
          FOR i IN 1..tab.count
          LOOP
          ADD_GROUP_ROW ('RG10', END_OF_GROUP);
          SET_GROUP_CHAR_CELL ('RG10.COL1', i, tab(i));
          END LOOP;
     END IF;
END;Francois

Working around unchecked conversions when using reflection

I think I've convinced myself that there's no way around this issue when using reflection and Generics, but here's the issue:
Suppose I've got a method that uses reflection to compare an arbitrary property in
an arbitrary pair of beans (of the same class).
public static <T> int compare(T bean0, T bean1, String prop) throws Exception {
     Method m = bean0.getClass().getMethod(
               "get" + prop.substring(0,1).toUpperCase() +
               prop.substring(1));
     Object o0 = m.invoke(bean0);
     Object o1 = m.invoke(bean1);
     if (o0 instanceof Comparable &&
         o1 instanceof Comparable &&
         (o1.getClass().isAssignableFrom(o0.getClass()) ||
          o0.getClass().isAssignableFrom(o1.getClass()))) {
          return ((Comparable)o0).compareTo(o1); // compiler warning
     } else {
          return o0.toString().compareTo(o1.toString());
}There's no way that, in general, when using reflection to invoke methods, that you can coerce the types to avoid compile-time type safety warnings. I think the above code is guarranteed not to throw a runtime ClassCastException, but there's no way to write the code so that the compiler can guarrantee it. At least that's what I think. Am I wrong?

Ok it looks like you're dealing with a classloader issue. when you call that method, it is the equivelant of calling
Class.forName("Box", true, this.getClass().getClassLoader())The exception is thrown when your class's classloader cannot find the class box. try putting 'null' there
Class.forName("Box", true, null)and it will request the bootstrap classloader to load the class. just make sure you have permission :
If the loader is null, and a security manager is present, and the caller's class loader is not null, then this method calls the security manager's checkPermission method with a RuntimePermission("getClassLoader") permission to ensure it's ok to access the bootstrap class loader. (copied from the API)

Creating objects using reflection

Hi,
I need to construct a new instance using reflection and passing parameters. If the parameters are of primitive type ex. int, how can I pass them in the Class[] type of object

Integer.TYPE, etc. are Class objects that represent the types of the primitives.

Get Name of Variable using Reflection

Is there a way to get the variable name? I assume I'd have to use Reflection. Here's an example of what I mean.
Dim tileCount As Integer
' get tileCount variable name here
Debug.Print("tileCount")
Ryan

I need to validate a variable. If the variable isn't valid I want to throw an ArgumentOutOfRangeException.
Variable names are internal to your program. They don't actually exist as part of your executable code, but it is possible with reflection to look back into the source code and find certain information. But it is not possible
to identify a variable by its value. However, you should not be using variable names to identify your objects.
If you create a class for your values then you can build a IsValid test for the value field of the class, and return information about the class instance. For example:
Public Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim thisTile As New Tile With {.Height = 7, .Name = "Fred"}
If Not thisTile.IsValidHeight Then
Throw New ArgumentOutOfRangeException("Instance", thisTile.Name, String.Format("{0} is not a valid tile height.", thisTile.Name))
End If
End Sub
End Class
Public Class Tile
Public Name As String
Public Height As Integer
Public Function IsValidHeight() As Boolean
Dim myArray() As Integer = {3, 4, 6, 7}
If Not myArray.Contains(Me.Height) Then
Return True
Else
Return False
End If
End Function
End Class
Great idea! :)
Still lost in code, just at a little higher level.

Is it a must to use Solution manager for ECC 6.0 upgrade

Is it a must to use Solution Manager for ECC 6.0 (FICO & HR) upgrade? I am told Solution Manager is required only if it has ABAP and JAVA stacks, or involves Enhancement Packages; and could be optional if it is only ECC 6.0 with ABAP stacks.

Hi,
I'm having a difficult time finding some guidance for setting up our R/3 Enterprise system in solman properly, so that I can create the upgrade XML file required to go directly to ERP 6.0 EHP4.
I've set up the R/3 system fine, but when i create a maintenance transaction i cannot for the life of me figure out how to tell it I want to go from r/3 to ERP6 ehp4.
Any docs out there for this?
Thanks!
I figured it out... i had to add the R/3 Enterprise logical components to my system landscape. After that I was able to select R/3 as the initial data in the maintenance transaction and then the system i wanted to upgrade, and then the option to upgrade.
Never mind!
Edited by: Tom Janes on Sep 9, 2009 12:52 AM

Using Reflection can we find out details of inner classes in a class

Hello All,
Thanx in advance.
I intend to figure out the name of the inner class and methods declared inside it. How can this be done using reflection API's.
I need the above information to make an automated java doc creation tool for the project I am working in.
Thanx again...
VIkas

Thanx silkm,
Actually suggestion # 1 I have already tried. I used
getClasses() method which returned me a Class[] of
length = 0. i dunno Why?Because you are not using the reflection API correctly. If you read the javadocs you would know that it is structured so that all getXXX() methods return all XXX things that are public and are either declared by the target class or possibly inherited from superclasses.
As contrasted to that, getDeclaredXXX() methods can return all XXX things (including private) but only declared by the target class (not inherited).
You got an empty result back in your case most likely because all your nested/inner classes were non-public. Use getDeclaredClasses() instead.
As to suggestion # 2, the exercise I am doing is a
step before using the java doc tool. One has to insert
a javadoc comment before the method begins in order to
create a java doc. So thats it.This is independent of the reflection API but you might consider using the doclet API for this.

Must I Use Reflection?

Similar Messages

Maybe you are looking for