Type cast with string name

I have a hashtable full of Objects. I also have there type represented by a String. How can I typecast these Objects back to there type. i.e.
String str = "helpme";
str = (Object)str;
String type = "String";
can I use the var type to cast str back to a String;

I've never used reflection before so my answer maybe way off from what you're looking for.... but to solve your problem on casting an Object to a type specified by a String variable you could use a case or if statement if you know what types are available ahead of time and call the appropriate methods to return your Object type.
For example... You could create a method for each type you expect to return.
public String getStringValue( Object obj ) {
     return (String)obj;
public Integer getIntegerValue( Object obj ) {
     return (Integer)obj;
public Byte getByteValue( Object obj ) {
     return (Byte)obj;
}Then... depending on what the value of your String type variable is you can call the appropriate method that will return the Object type you're wanting.
String type = "String";
if( type.equals("String") )
     String yourStr = getStringValue(yourObject);
else if( type.equals("Integer") )
     Integer yourInt = getIntegerValue(yourObject);
else if( type.equals("Byte") )
     Byte yourByte = getByteValue(yourObject);This maybe not be the most efficient way especially since there can be potential errors but it can work assuming the String type is really representing the type of Object yourObject is.
I don't know.. just a possible solution that popped in my head.
.kim

Similar Messages

Type cast with String representation

I have a hashtable full of Objects along with a String representation of their type. Is it possible to cast an Object back using a String representation of its type. ie
String str = "helpme";
String type = "String";
str = (Object)str;
now I want to get str back to String type but with using the variable type.

Do not crosspost: http://forum.java.sun.com/thread.jsp?thread=355714&forum=4&message=1482427

Splitting and type casting huge string into arrays

Hello,
I'm developing an application which is supposed to read measurement files. Files contain I16 and SGL data which is type casted into string. I16 data is data from analog input and SGL is from CAN-bus data in channel form. CAN and analog data is recorded using same scan rate.
For example, if we have 6 analog channels and 2 CAN channels string will be (A represents analog and C represents CAN):
A1 A2 A3 A4 A5 A6 C1 C2 A1 A2 A3 A4 A5 A6 C1 C2 A1 A2 .... and so on
Anyway, I have problems reading this data fast enough into arrays. Most obvious solution to me was to use shift registers and split string in for loop. I created a for loop with two inner for loops. Number of scans to read from string is wired to N terminal of the outermost loop. Shift register is initialized with string read from file.
First of the inner loops reads analog input data. Number of analog channels is wired to its N terminal. It's using split string to read 2 bytes at a time and then type casts data to I16. Rest of the string is wired to shift register. When every I16 channel from scan is read, rest of the string is passed to shift register of the second for loop.
Second loop is for reading CAN channels. It's similar to first loop except data is read 4 bytes at a time and type casted to SGL. When every CAN channel from scan is read, rest of the string is passed to shift register of the outermost loop. Outputs of type cast functions are tunneled out of loops to produce 2D arrays.
This way reading about 500 KB of data can take for example tens of seconds depending on PC and number of channels. That's way too long as we want to read several megabytes at a time.
I created also an example with one inner loop and all data is type casted to I16. That is extremely fast when compared to two inner loops!
Then I also made a test with two inner loops where I replaced shift register and split string with string subset. That's also faster than two inner loops + shift register, but still not fast enough. Any improvement ideas are highly appreciated. Shift register example attached (LV 7.1)
Thanks in advance,
Jakke Palonen
Attachments:
String to I16 and SGL arrays.vi ‏39 KB

OK, there is clearly room for improvement. I did some timing and my two above suggestions are already about 100x faster than yours. A few teeaks led to a version that is now over 500x faster than the original code.
A few timings on my rather slow computer (1GHz PIII Laptop) are shown on the front panel. For example with 10000 scans (~160kB data as 6+2) my new fastest version (Reshape II) takes 14 ms versus the original 7200ms! It can do 100000 scans (1.6MB data) in under 200 ms and 1000000 scans (15MB data) in under 2 seconds.
I am sure the code could be further improved. I recommend the Reshape II algoritm. It is fastest and can deal with variable channel counts. Modify as needed.
Attached is a LabVIEW 7.1 version of the benchmarking code, containing all algorithms. I have verified that all algorithms produce the same result (with the limitation that the cluster version only works for 6*I16+2*SGL data, of course). Remember that the reshape function is extremely efficient, because it does not move the data in memory. I have some ideas for further improvements, but this should get you going.
Message Edited by altenbach on 08-05-2005 03:06 PM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
StringI16SGLCastingTimer.png ‏48 KB
StringtoI16andSGLArraysMODTimer.vi ‏120 KB

How to use type cast change string to number(dbl)?can it work?

how to use type cast change string to number(dbl)?can it work?

Do you want to Type Cast (function in the Advanced >> Data Manipulation palette) or Convert (functions in the String >> String/Number Conversion palette)?
2 simple examples:
"1" cast as I8 = 49 or 31 hex.
"1" converted to decimal = 1.
"20" cast as I16 = 12848 or 3230 hex.
"20" converted to decimal = 20.
Note that type casting a string to an integer results in a byte by byte conversion to the ASCII values.
32 hex is an ASCII "2" and 30 hex is an ASCII "0" so "20" cast as I16 becomes 3230 hex.
When type casting a string to a double, the string must conform the the IEEE 32 bit floating point representation, which is typically not easy to enter from the keyboard.
See tha attached LabView 6.1 example.
Attachments:
TypeCastAndConvert.vi ‏34 KB

DatabaseProcedure with return type prefixed with schema name

Hi (Paco)
I have a question about the DatabaseProcedure class. We are using Oracle proxy users for our database connections.
Everything is accessed via a database role that are granted to the logged on user. All our database objects, tables etc are protected with this database role.
When I want to call a database function/procedure I need to add the schema name as a prefix to the custom database object that we uses for parameters/return types.
So far so good. I can also define a parameter prefixed with schema name via the DatabaseProcedure.registerArrayType ...
But when I try to define a function call that uses this parameter I get an error saying "Declaration is not valid".
The problem is located to the PROCEDURE_DEFINITION regular pattern:
private static final Pattern PROCEDURE_DEFINITION = Pattern.compile("\\s* (FUNCTION|PROCEDURE) \\s+ ([\\w.$]+) \\s* (?:\$(.*?)\$)? \\s* (?:RETURN\\s+(\\w+))? \\s* ;? \\s*", CASE_INSENSITIVE | COMMENTS | DOTALL); The return type cannot be prefixed with the schema name.
Any good suggestions or workarounds?!
I actually did change the pattern runtime via reflection to make it work - but I really don't like this solution in the long run!
/Torben
Edited by: Zonic on 2013-05-07 10:52

Hi Torben,
I think I have a workaround for the issue that might work for you. If you look at the source of DatabaseProcedure.registerArrayType you find that it actually calls DatabaseProcedure.registerCustomParamType.
public static void registerArrayType(String name)
registerCustomParamType(name, Types.ARRAY, Array.getORADataFactory(), name);
}As a workaround you could replace your calls to DatabaseProcedure.registerArrayType with calls to DatabaseProcedure.registerCustomParamType as follows.
// Instead of DatabaseProcedure.registerArrayType("NAME.WITH.DOTS") call:
DatabaseProcedure.registerCustomParamType("anyNameWithoutDots", Types.ARRAY, Array.getORADataFactory(), "NAME.WITH.DOTS"); // Don't forget to use uppercase here.
DatabaseProcedure dp = DatabaseProcedure.define("procedure my.procedure(param1 in out anyNameWithoutDots)");
DatabaseProcedure.ParamType type = dp.getParamDef(0).getType();
System.out.println(type.getName() + " is " + type.getTypeName()); // ANYNAMEWITHOUTDOTS is NAME.WITH.DOTSThis way you don't have to use the "illegal" name in the DatabaseProcedure definition.
Regards,
Paco van der Linden

Type cast with operator +=

Hi,
can somebody explain me, why the java compiler complains about a missing type cast (which is good) in
int a = 0;
double b = 1.3;
a = a + b; // compiler error (missing type cast)but does not complain when using the += shorthand form?
int a = 0;
double b = 1.3;
a += b; // works (!)Thanks,
Michael

Because the compound assignment operator has an implied cast.
A compound assignment expression of the form E1 op= E2 is equivalent to E1 = (T)((E1) op (E2)), where T is the type of E1, except that E1 is evaluated only once.

Generating target-type xsd with element names in camelCase

Env: ODSI 10gR3, Workshop 10gR3, Oracle DB 10gR3
We are developing logical data services following a bottom up approach. The source physical data services that we use to build the logical ds have xsd definitions in which element names are in CAPS_CAPS naming convention (following the same names as the database tables). For example, FIRST_NAME, LAST_NAME, etc.
When we use Query Map to generate xsd for the target types of the logical ds, it generates element names that are also in the CAPS_CAPS convention. Is there a way to generate the target type xsd in which CAPS_CAPS names are converted to camelCase, e.g. FIRST_NAME becomes firstName.
Thank you in advance.

mixed-case with underscores removed vs. upper case is only one variation. Someone might like to rename SSN to SocialSecurityNumber, someone might like to rename LAST_NAME to Surname or FamilyName etc.
You can do any renaming etc. with a Logical Data Service. See the "Best Practices" which is posted as an Announcement in this forum.
Typically customers put their Physical (i.e. generated) data services in a Physical folder, and then create a parallel Logical folder (including the schemas folder). Then you would create new schemas in Logical/schemas with the new names, create new Logical data services to match the physical ones, then create a 'read' function that uses the physical read function and map the elements of the physical read function to the logical schema (with the new names). Then you can generate the create/delete/update procedures in the Logical data services.
Getting back to your original question - the answer is No. There is no feature with in ODSI to automatically transform element names to something else.
- Mike

Creating Objects with String name

How can i create an object, but just having the name as String?
Like, instead of creating like JInternalFrame obj = new MyInternalFrame(), do it like JInternalFrame obj = createObject("MyInternalFrame") ( i just gave createObject as example, ignore it)...
Does anyone knows how to do it? Because i have several windows, and by clicking, i dont want to be with a lot of if clauses checking each one to se wich one is the ritgh class to call...
Tks,
Bruno

You need the Class class in package java.lang, specifically class (static) method forName() and instance method newInstance():
JInternalFrame obj =
(JInternalFrame) Class.forName("MyInternalFrame").newInstance();

TYPE casting with SQL Server 2005

Hi,
I recently migrated to SQL Server 2005 database from Oracle 10g. I used the %TYPE operator in Oracle to cast to the appropriate column data type.
PROCEDURE INS_USER
i_USERNAME IN USERS.USERNAME%TYPE,
i_PASSWORD IN USERS.PASSWORD%TYPE,
IS BEGIN
How can I do this in SQL Server 2005? Is there any similar operator to %TYPE in SQL Server??

i don't know !
you can try a SQL server forum.

Type casting with dblink?

Hi!
I want to use an functions result for both a call to local procedure and an remote procedure.
When I want to call an remote procedure, I must declare the (return)variable and return-signature
as "remote type", e.g. using @dblinkname
the function i write is of general purpose so I want to deploy it on local and remote site. I could deploy it locally using ...@dblinkname and remote without.
But I would like to use on version of the same code and not two, so I tried this:
codelines dbms_sql.varchar2s@DL_PROD.WORLD;
codelinesl dbms_sql.varchar2s;
codelinesl := f();
codelines := cast (codelines as dbms_sql.varchar2s@DL_PROD.WORLD);
and got pls-00220

the function i write is of general purpose so I want
to deploy it on local and remote site. I could deploy
it locally using ...@dblinkname and remote without.
But I would like to use on version of the same code
and not two,Why would the use of the function in the above example result into two versions?

Is there a way to type cast an array of strings to numbers and back again?

I'm working on an application where I want to type cast a string like "power supply" into an array of existing numbers. Then sort the existing numbers, and finally convert the casted numbers back into a string so it can be read by the user. In the attachment, you can see my latest attempt with flatten/unflatten data and the 'convert string to byte array'. I can't seem to make this work. Any ideas?
Thanks - Paul
Attachments:
Paul's Temp scan for components.vi ‏56 KB

OK, here's a quickie (LabVIEW 7.0).
Simply get the sort key from the 1D array, then build the table.
Message Edited by altenbach on 10-27-2006 01:34 PM
LabVIEW Champion . Do more with less code and in less time .
Attachments:
SortedTable.png ‏4 KB
SortedTable.vi ‏37 KB

J2SE 6 warning message when using type casting

With Java SE 5 and 6 version, there's always an annoying warning message when I write the following code:
LinkedList<MyBean> cart0 = (LinkedList<MyBean>) session.getAttribute("cart");The warning message is because I use the type casting with the getAttribute method and thus this is not type-safe. So how do I get around the warning message and write standard code that sticks to the J2SE 6 standards? Thank you.

Add a @SuppressWarnings annotation to the method. A bit intelligent IDE will provide you a quickfix option for it.
Keep in mind: it's a warning, not an error. The sessionMap is cannot be specifically parameterized and will never be, it should be able to store any object to your taste. Further on this has not much to do with JSF at itself.

SSMS 2012:XQuery-doing "Retriving Job Candidates with the query Method" in AdventuresWorks 2012. Unclosed quotation mark after string '//*:Name.First?

Hi all,
From Page 354 of the the Book "Pro T-SQL 2008 Programmer's Guide" written by Michael Coles (published by apress), I copied the following code (Listing 12-9 Retrieving Job Candidates with the query Method):
--Coles12_9.sql // saved in C:/Documemnts/SQL Server Management Studio
-- Coles Listing 12-9 Retrieving Job Candidates with the query Method
-- Doing XQuery and the xml Data Type in AdvantureWorks
-- 17 March 2015 1105 AM
USE AdventureWorks;
GO
SELECT Resume.query
N'//*:Name.First,
//*:Name.Middle,
//*:Name.Last,
//*:Edu.Level
FROM HumanResources.JobCandidate;
I executed this set of Listing 12-9 code in my SQL Server 2012 Management Studio and I got the following error messages:
Msg 105, Level 15, State 1, Line 4
Unclosed quotation mark after the character string '//*:Name.First,
//*:Name.Middle,
//*:Name.Last,
//*:Edu.Level
FROM HumanResources.JobCandidate;
Msg 102, Level 15, State 1, Line 4
Incorrect syntax near '//*:Name.First,
//*:Name.Middle,
//*:Name.Last,
//*:Edu.Level
FROM HumanResources.JobCandidate;
I am not able to figure out why I got the error messages. Please kindly help and advise me how to correct this set of sql codes.
Thanks in advance,
Scott Chang

Hi Scott,
I don't have that book at hand, but your problem is the "Unclosed quotationmark after the character string",as the error message shows. You have to enclose the 'XQUERY' string quotation in the
query().
SELECT jobcandidateid, Resume.query
N'//*:resume,
//*:Name.Middle,
//*:Name.Last,
//*:Edu.Level' --enclose the quotation here
FROM HumanResources.JobCandidate;
For XQUERY learning, here is a good
link.
If you have any question, feel free to let me know.
Eric Zhang
TechNet Community Support

Two methods with same name but different return type?

Can I have two methods with same name but different return type in Java? I used to do this in C++ (method overloading or function overloading)
Here is my code:
import java.io.*;
public class Test{
public static void main(String ar[]){
try{
//I give an invalid file name to throw IO error.
File file = new File("c:/invalid file name becasue of spaces");
FileWriter writer = new FileWriter(file ,true);
writer.write("Test");
writer.close();
} catch (IOException IOe){
     System.out.println("Failure");
//call first method - displays stack trace on screen
     showerr(NPe);
//call second method - returns stack trace as string
        String msg = showerr(NPe);
        System.out.println(msg);
} // end of main
public static void showerr(Exception e){
     StringWriter sw = new StringWriter();
     PrintWriter pw = new PrintWriter(sw);
     e.printStackTrace(pw);
     try{
     pw.close();
     sw.close();
     catch (IOException IOe){
     IOe.printStackTrace();
     String stackTrace = sw.toString();
     System.out.println("Null Ptr\n" + stackTrace );
}//end of first showerr
public static String showerr(Exception e){
     StringWriter sw = new StringWriter();
     PrintWriter pw = new PrintWriter(sw);
     e.printStackTrace(pw);
     try{
     pw.close();
     sw.close();
     catch (IOException IOe){
     IOe.printStackTrace();
     return sw.toString();
}//end of second showerr
} // end of class
[\code]

Overloading is when you have multiple methods that have the same name and the same return type but take different parameters. See example
public class Overloader {
     public String buildError(Exception e){
          java.util.Date now = new java.util.Date() ;
          java.text.DateFormat format = java.text.DateFormat.getInstance() ;
          StringBuffer buffer = new StringBuffer() ;
          buffer.append(format.format(now))
               .append( " : " )
               .append( e.getClass().getName() )
               .append( " : " )
               .append( e.getMessage() ) ;
          return buffer.toString() ;
     public String buildError(String msg){
          java.util.Date now = new java.util.Date() ;
          java.text.DateFormat format = java.text.DateFormat.getInstance() ;
          StringBuffer buffer = new StringBuffer() ;
          buffer.append(format.format(now))
               .append( " : " )
               .append( msg ) ;
          return buffer.toString() ;
     public String buildErrors(int errCount){
          java.util.Date now = new java.util.Date() ;
          java.text.DateFormat format = java.text.DateFormat.getInstance() ;
          StringBuffer buffer = new StringBuffer() ;
          buffer.append(format.format(now))
               .append( " : " )
               .append( "There have been " )
               .append( errCount )
               .append( " errors encountered.") ;
          return buffer.toString() ;
}Make sense ???
Regards,

Native method with String return type

Hi
i am implementing a Native method with String Return type.
i am able call the respective C++ method and my C++ method is printing the String (jstring in c++ code ) correctly
i but i am getting nullpointerexcepti while loading the string in to my Java String .
i am sure my java code calling the C++ code beacause my C++ code is printing the value and one more wonder is after the NPE my c++ code able to print the value
the code follows
HelloWorld.java
public class HelloWorld {
 private native String print();
 static {
 System.loadLibrary("HelloWorld");
 public static void main(String[] args) throws InterruptedException,NullPointerException{
 HelloWorld hW= new HelloWorld();
 for(int i=0;;i++){
 String str= new HelloWorld().print();
 System.out.println(str);
 Thread.sleep(10000);
}and HelloWorld.cpp
// HelloWorld.cpp : Defines the entry point for the DLL application.
#include "stdafx.h"
#include "jni.h"
#include <stdio.h>
#include "HelloWorld.h"
#include <windows.h>
#include "tchar.h"
#include "string.h"
#ifdef _MANAGED
#pragma managed(push, off)
#endif
CHAR cpuusage(void);
typedef BOOL ( __stdcall * pfnGetSystemTimes)( LPFILETIME lpIdleTime, LPFILETIME lpKernelTime, LPFILETIME lpUserTime );
static pfnGetSystemTimes s_pfnGetSystemTimes = NULL;
static HMODULE s_hKernel = NULL;
void GetSystemTimesAddress()
 if( s_hKernel == NULL )
 s_hKernel = LoadLibrary(_T("Kernel32.dll"));
 if( s_hKernel != NULL )
 s_pfnGetSystemTimes = (pfnGetSystemTimes)GetProcAddress( s_hKernel, "GetSystemTimes" );
 if( s_pfnGetSystemTimes == NULL )
 FreeLibrary( s_hKernel ); s_hKernel = NULL;
// cpuusage(void)
// ==============
// Return a CHAR value in the range 0 - 100 representing actual CPU usage in percent.
CHAR cpuusage()
 FILETIME ft_sys_idle;
 FILETIME ft_sys_kernel;
 FILETIME ft_sys_user;
 ULARGE_INTEGER ul_sys_idle;
 ULARGE_INTEGER ul_sys_kernel;
 ULARGE_INTEGER ul_sys_user;
 static ULARGE_INTEGER ul_sys_idle_old;
 static ULARGE_INTEGER ul_sys_kernel_old;
 static ULARGE_INTEGER ul_sys_user_old;
 CHAR usage = 0;
 // we cannot directly use GetSystemTimes on C language
 /* add this line :: pfnGetSystemTimes */
 s_pfnGetSystemTimes(&ft_sys_idle, /* System idle time */
 &ft_sys_kernel, /* system kernel time */
 &ft_sys_user); /* System user time */
 CopyMemory(&ul_sys_idle , &ft_sys_idle , sizeof(FILETIME)); // Could been optimized away...
 CopyMemory(&ul_sys_kernel, &ft_sys_kernel, sizeof(FILETIME)); // Could been optimized away...
 CopyMemory(&ul_sys_user , &ft_sys_user , sizeof(FILETIME)); // Could been optimized away...
 usage =
 (ul_sys_kernel.QuadPart - ul_sys_kernel_old.QuadPart)+
 (ul_sys_user.QuadPart - ul_sys_user_old.QuadPart)
 (ul_sys_idle.QuadPart-ul_sys_idle_old.QuadPart)
 (100)
 (ul_sys_kernel.QuadPart - ul_sys_kernel_old.QuadPart)+
 (ul_sys_user.QuadPart - ul_sys_user_old.QuadPart)
 ul_sys_idle_old.QuadPart = ul_sys_idle.QuadPart;
 ul_sys_user_old.QuadPart = ul_sys_user.QuadPart;
 ul_sys_kernel_old.QuadPart = ul_sys_kernel.QuadPart;
 return usage;
BOOL APIENTRY DllMain( HMODULE hModule,
 DWORD ul_reason_for_call,
 LPVOID lpReserved
 return TRUE;
#ifdef _MANAGED
#pragma managed(pop)
#endif
JNIEXPORT jstring JNICALL
Java_HelloWorld_print(JNIEnv *env, jobject obj)
 int n;
 GetSystemTimesAddress();
 jstring s=(jstring)cpuusage();
 printf("CPU Usage from C++: %3d%%\r",s);
 return s;
}actually in the above code below part does that all, in the below code the printf statement printing correctly
JNIEXPORT jstring JNICALL
Java_HelloWorld_print(JNIEnv *env, jobject obj)
 int n;
 GetSystemTimesAddress();
 jstring s=(jstring)cpuusage();
 printf("CPU Usage from C++: %3d%%\r",s);
 return s;
}and the NPE i get is
Exception in thread "main" java.lang.NullPointerException
 at HelloWorld.print(Native Method)
 at HelloWorld.main(HelloWorld.java:10)
CPU Usage from C++: 6%any solution?
Thanks
R
Edited by: LoveOpensource on Apr 28, 2008 12:38 AM

See the function you wrote:
JNIEXPORT jstring JNICALL Java_HelloWorld_print(JNIEnv *env, jobject obj)
 int n;
 GetSystemTimesAddress();
 _jstring s=(jstring)cpuusage();_
 printf("CPU Usage from C++: %3d%%\r",s);
 return s;
}Here you try to cast from char to jstring, this is your problem, jstring Object should be created:
char str[20];
sprintf(str, "%3d", (int)cpuusage());
printf("CPU Usage from C++: %s%%\r",str);
jstring s=env->NewStringUTF(str);
return s;

Type cast with string name

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