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  1. JDK
  2. JDK-5015403

LTP: XMLEncoder does not encode enumerations correctly

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    • Subcomponent:
    • Resolved In Build:
      b84
    • CPU:
      x86
    • OS:
      linux, windows_xp

      Description

      Name: rmT116609 Date: 03/17/2004


      FULL PRODUCT VERSION :

      [cheiny@venom encoderbug]$ java -version
      java version "1.5.0-beta"
      Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0-beta-b32c)
      Java HotSpot(TM) Client VM (build 1.5.0-beta-b32c, mixed mode)
      [cheiny@venom encoderbug]$

      ADDITIONAL OS VERSION INFORMATION :

      [cheiny@venom encoderbug]$ uname -a
      Linux venom 2.4.20-8 #1 Thu Mar 13 17:18:24 EST 2003 i686 athlon i386 GNU/Linux
      [cheiny@venom encoderbug]$

      A DESCRIPTION OF THE PROBLEM :
      XMLEncoder is not serializing an enumeration correctly. Instead it is allowing the field/property to default. This is not good - the serialized information cannot be read back. Result data is lost.

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      1) Save the source code in the attached examples as BugBean.java and BugMain.java

      2) compile with "javac -source 1.5 BugBean.java BugMain.java"

      3) run with "java -cp . BugMain"

      4) Look in the file "bb.out" to see the serialized bean.

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      5 - expected) property plaf should be equal to Metal (or something like that)
      ACTUAL -
      5 - actual) the plaf property is defaulted.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      /*
       * BugBean.java
       *
       * Created on March 17, 2004, 12:24 PM
       */

      import java.beans.*;
      import java.io.Serializable;

      /**
       * @author cheiny
       */
      public class BugBean extends Object implements Serializable {
          
          public enum Plaf {metal, windows, gtk, unknown}
          
          private PropertyChangeSupport propertySupport;
          
          /**
           * Holds value of property plaf.
           */
          private Plaf plaf = Plaf.unknown;
          
          public BugBean() {
              propertySupport = new PropertyChangeSupport(this);
          }
          
          
          public void addPropertyChangeListener(PropertyChangeListener listener) {
              propertySupport.addPropertyChangeListener(listener);
          }
          
          public void removePropertyChangeListener(PropertyChangeListener listener) {
              propertySupport.removePropertyChangeListener(listener);
          }
          
          /**
           * Getter for property plaf.
           * @return Value of property plaf.
           */
          public Plaf getPlaf() {
              return this.plaf;
          }
          
          /**
           * Setter for property plaf.
           * @param plaf New value of property plaf.
           */
          public void setPlaf(Plaf plaf) {
              Plaf oldPlaf = this.plaf;
              this.plaf = plaf;
              propertySupport.firePropertyChange("plaf", oldPlaf, plaf);
          }
          
      }




      /*
       * BugMain.java
       *
       * Created on March 17, 2004, 12:29 PM
       */

      import java.io.*;
      import java.beans.*;

      /**
       *
       * @author cheiny
       */
      public class BugMain {
          
          /** Creates a new instance of BugMain */
          public BugMain() {
          }
          
          /**
           * @param args the command line arguments
           */
          public static void main(String[] args) {
              BugBean bb = new BugBean();
          
              File f = new java.io.File("bb.out");
              
              bb.setPlaf(BugBean.Plaf.metal);
              try {
                  XMLEncoder e = new XMLEncoder(
                      new BufferedOutputStream(
                          new FileOutputStream(f)));
                  System.out.println("Saving to " + f.getAbsoluteFile() + ". Plaf = " + bb.getPlaf());
                  e.writeObject(bb);
                  e.flush();
                  e.close();
              System.out.println(" done, plaf = " + bb.getPlaf());
              } catch ( Exception x ) {
                  System.err.println("Failed to save preferences: " + x.getMessage());
              }
          }
          
      }

      ---------- END SOURCE ----------
      (Incident Review ID: 243958)
      ======================================================================

      CUSTOMER SUBMITTED WORKAROUND :
      Install a delegate. The same delegate will work for all enum types.

      import java.util.*;
      import java.beans.*;

      class EnumDelegate extends DefaultPersistenceDelegate
      {
         protected Expression instantiate(Object oldInstance, Encoder out)
         {
            return new Expression(Enum.class,
               "valueOf",
               new Object[] { oldInstance.getClass(), ((Enum) oldInstance).name() });
         }
         protected boolean mutatesTo(Object oldInstance, Object newInstance)
         {
            return oldInstance == newInstance;
         }
      }

      With this workaround, this test case
      <test case>
      enum Mood { SAD, HAPPY };

      public class Test2
      {
         public static void main(String[] args)
         {
            XMLEncoder out = new XMLEncoder(System.out);
            out.setPersistenceDelegate(Mood.class, new EnumDelegate());
            out.writeObject(Mood.SAD);
            out.close();
         }
      }
      </test case>


      should write an expression that encodes Mood.SAD such as

      <object class="java.lang.Enum" method="valueOf">
        <class>Mood</class>
        <string>SAD</string>
       </object>

      ###@###.### 2004-09-02

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              Assignee:
              malenkov Sergey Malenkov (Inactive)
              Reporter:
              rmandalasunw Ranjith Mandala (Inactive)
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