|
|
You're in the
vj#
group:Serialization for Double in J#
vj#:
Hi
While trying to execute a code which does serialization of object i am getting following erro "There was an error generating the XML document. and the InnerException after debugging show {"java.lang.Double cannot be serialized because it does not have a default public constructor." Can anyone suggest me how to solve i Thank Vina
Works for me. I don't know what could be wrong, you don't post your code.
public class serializeme implements java.io.Serializable { public java.lang.Double value; } /** * Summary description for Class1. */ public class Class1 { public Class1() { try { // ______------ Object ------______ // Wrire serializeme one = new serializeme(); one.value = new java.lang.Double(4.5); java.io.FileOutputStream file = new java.io.FileOutputStream( "fileout" ); java.io.ObjectOutputStream output = new java.io.ObjectOutputStream( file ); output.writeObject( one ); output.flush(); output.close(); file.close(); System.out.println( "(Written) Serialized :"+one.value ); // Read serializeme two; java.io.File file2 = new java.io.File( "fileout" ); java.io.FileInputStream fileinstream = new java.io.FileInputStream( file2 ); java.io.ObjectInputStream objstream = new java.io.ObjectInputStream( fileinstream ); two = (serializeme)objstream.readObject(); System.out.println( "(Read) Serialized :"+two.value ); objstream.close(); fileinstream.close(); // ______------ Double ------______ // Write java.lang.Double doub = new java.lang.Double( 6.6 ); java.io.FileOutputStream file3 = new java.io.FileOutputStream( "fileout2" ); java.io.ObjectOutputStream output3 = new java.io.ObjectOutputStream( file3 ); output3.writeDouble( doub.doubleValue() ); output3.flush(); output3.close(); file3.close(); System.out.println( "(Written) Serialized :"+doub ); // Read java.lang.Double doub2; java.io.File file4 = new java.io.File( "fileout2" ); java.io.FileInputStream fileinstream4 = new java.io.FileInputStream( file4 ); java.io.ObjectInputStream objstream4 = new java.io.ObjectInputStream( fileinstream4 ); doub2 = new java.lang.Double( (double)objstream4.readDouble() ); System.out.println( "(Read) Serialized :"+doub2 ); objstream4.close(); fileinstream4.close(); // ______------ double ------______ // Write double doub5 = 2.9; java.io.FileOutputStream file5 = new java.io.FileOutputStream( "fileout5" ); java.io.ObjectOutputStream output5 = new java.io.ObjectOutputStream( file5 ); output5.writeDouble( doub5 ); output5.flush(); output5.close(); file5.close(); System.out.println( "(Written) Serialized :"+doub5 ); // Read double doub6; java.io.File file6 = new java.io.File( "fileout5" ); java.io.FileInputStream fileinstream6 = new java.io.FileInputStream( file6 ); java.io.ObjectInputStream objstream6 = new java.io.ObjectInputStream( fileinstream6 ); doub6 = objstream6.readDouble(); System.out.println( "(Read) Serialized :"+doub6 ); objstream6.close(); fileinstream6.close(); } catch ( java.io.IOException ioexception ) { ioexception.printStackTrace(); } catch ( java.lang.ClassNotFoundException notfound ) { notfound.printStackTrace(); } } /** @attribute System.STAThread() */ public static void main(String[] args) { new Class1(); } } Regards, Lars-Inge Tønnessen www.larsinge.com
In your code you're checking yourself that the object you serialize is
java.lang.Double and convert it to "double" (a primitive type, not a descendent of java.lang.Object if I do remember well) yourself manually using readDouble/writeDouble (which writes "double" values, not "java.lang.Double" object instances btw.). Suppose user wants to call readObject/writeObject (or however it's called and pass to it a java.lang.Double instance reference), that's the case reported the problem seems to be the java.lang.Double class doesn't have a default public constructor (with empty parameter list that is). In Sun's Java too, the Double doesn't have such a constructor, that is you can't do "Double x = new Double();" (say imply the 0 value), you have to do "Double x = new Double(0);" or "Double x = new Double(0d);" for example. class Double extends java.lang.Number implements java.lang.Comparable but java.lang.Number is "abstract" class so it has no constructor either (java.lang.Number extends java.lang.Object [it's implied - in the Number class implementation it doesn't declare explicitly that it extends Object]) the question is, should Double be Serializable? What happens in Sun Java? I think there too it can't serialize (which is bad of course). Maybe should check Java1.5 too plus the BugParade website at java.sun.com to see if people have been asking for this to be fixed at Sun Java (plus how many votes it has) and if it's scheduled to be fixed or the Sun engineers replied that's by design and won't be fixed. The problem is either at the Serialization logic, in that it should have special hardcoded handling maybe for the primitive-type wrapper classes of java.lang.* (meaning Double, Integer etc. classes), or at the Double class in that it could have an empty constructor that says: public Double() { this(0); } that is it sets the value 0 by calling the Double(double x) constructor of the same class cheers, George ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ George Birbilis <birbilis@kagi.com> [MVP J#] [9880] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + QuickTime VCL and ActiveX controls (for PowerPoint/VB/Delphi etc.) + Plugs VCL and ActiveX controls (InterProcess/Internet communication) + TransFormations, VB6 forms to ASP.net WebForms convertion http://www.kagi.com/birbilis + Robotics http://www.mech.upatras.gr/~robgroup ......................................................................... [quoted text, click to view] > Works for me. I don't know what could be wrong, you don't post your code. > > public class serializeme implements java.io.Serializable > { > public java.lang.Double value; > } > > /** > * Summary description for Class1. > */ > public class Class1 > { > public Class1() > { > try > { > // ______------ Object ------______ > > // Wrire > serializeme one = new serializeme(); > one.value = new java.lang.Double(4.5); > java.io.FileOutputStream file = new java.io.FileOutputStream( > "fileout" ); > java.io.ObjectOutputStream output = new > java.io.ObjectOutputStream( file ); > output.writeObject( one ); > output.flush(); > output.close(); > file.close(); > System.out.println( "(Written) Serialized :"+one.value ); > > // Read > serializeme two; > java.io.File file2 = new java.io.File( "fileout" ); > java.io.FileInputStream fileinstream = new > java.io.FileInputStream( file2 ); > java.io.ObjectInputStream objstream = new > java.io.ObjectInputStream( fileinstream ); > two = (serializeme)objstream.readObject(); > System.out.println( "(Read) Serialized :"+two.value ); > objstream.close(); > fileinstream.close(); > > // ______------ Double ------______ > // Write > java.lang.Double doub = new java.lang.Double( 6.6 ); > java.io.FileOutputStream file3 = new java.io.FileOutputStream( > "fileout2" ); > java.io.ObjectOutputStream output3 = new > java.io.ObjectOutputStream( file3 ); > output3.writeDouble( doub.doubleValue() ); > output3.flush(); > output3.close(); > file3.close(); > System.out.println( "(Written) Serialized :"+doub ); > > // Read > java.lang.Double doub2; > java.io.File file4 = new java.io.File( "fileout2" ); > java.io.FileInputStream fileinstream4 = new > java.io.FileInputStream( file4 ); > java.io.ObjectInputStream objstream4 = new > java.io.ObjectInputStream( fileinstream4 ); > doub2 = new java.lang.Double( (double)objstream4.readDouble() ); > System.out.println( "(Read) Serialized :"+doub2 ); > objstream4.close(); > fileinstream4.close(); > > // ______------ double ------______ > // Write > double doub5 = 2.9; > java.io.FileOutputStream file5 = new java.io.FileOutputStream( > "fileout5" ); > java.io.ObjectOutputStream output5 = new > java.io.ObjectOutputStream( file5 ); > output5.writeDouble( doub5 ); > output5.flush(); > output5.close(); > file5.close(); > System.out.println( "(Written) Serialized :"+doub5 ); > > // Read > double doub6; > java.io.File file6 = new java.io.File( "fileout5" ); > java.io.FileInputStream fileinstream6 = new > java.io.FileInputStream( file6 ); > java.io.ObjectInputStream objstream6 = new > java.io.ObjectInputStream( fileinstream6 ); > doub6 = objstream6.readDouble(); > System.out.println( "(Read) Serialized :"+doub6 ); > objstream6.close(); > fileinstream6.close(); > } > catch ( java.io.IOException ioexception ) > { > ioexception.printStackTrace(); > } > catch ( java.lang.ClassNotFoundException notfound ) > { > notfound.printStackTrace(); > } > } > > /** @attribute System.STAThread() */ > public static void main(String[] args) > { > new Class1(); > } > } > > > > Regards, > Lars-Inge Tønnessen > www.larsinge.com > >
Don't see what you're looking for? Try a search.
|
October 2003
November 2003
December 2003
January 2004
February 2004
March 2004
April 2004
May 2004
June 2004
July 2004
August 2004
September 2004
October 2004
November 2004
December 2004
January 2005
February 2005
March 2005
April 2005
May 2005
June 2005
July 2005
August 2005
September 2005
October 2005
November 2005
December 2005
February 2006
March 2006
April 2006
May 2006
June 2006
July 2006
August 2006
September 2006
October 2006
December 2006
January 2007
February 2007
April 2007
July 2007
August 2007
| home · blog · groups | Questions? Comments? Contact the dn |