Hi Claus,

You can make the enum compute the boolean based on its name. Or is
your On|Off enum just some sample enum and not your real enum?

It's just a sample Enum to describe the general problem.

Camel 2.x is EOL and we wont do changes there.
Only CVEs and production bug fixes.

Do you think it's a design problem? And is it the same in Camel 3.x?

-Ralf

On 2/28/20 7:43 AM, Claus Ibsen wrote:
Hi

You can make the enum compute the boolean based on its name. Or is
your On|Off enum just some sample enum and not your real enum?

Camel 2.x is EOL and we wont do changes there.
Only CVEs and production bug fixes.




On Wed, Feb 26, 2020 at 2:54 PM Ralf Claussnitzer
<[email protected]> wrote:
Dear list,

I noticed a problem in Camel 2.x with type conversion of Enums. It
cannot be used with constructor type Enums. The conversion of Strings to
Enum types is hard coded to fail with an Exception if the EnumConverter
cannot instantiate an Enum value.

Given the Enum:

     enum Toggle {
              On(true), Off(false);

              private final boolean b;

              Toggle(boolean b) {
                  this.b = b;
              }

              @Override
              public String toString() {
                  return String.format("%s(%b)", name(), b);
              }
     }

A call to convertTo() can only find the appropriate Enum object by name:

     CamelContext context = new DefaultCamelContext();
     Toggle toggle = context.getTypeConverter().convertTo(Toggle.class,
     "On");
     System.out.println(toggle); // ...On(true)

However, I cannot introduce a custom TypeConverter for converting the
String "On(true)" into an instance of Toggle. The reason is that
org.apache.camel.impl.converter.EnumTypeConverter tries to call the
built-in valueOf(String) method which will end the program with a
RuntimeException:

     Exception in thread "main" org.apache.camel.TypeConversionException:
     Error during type conversion from type: java.lang.String to the
     required type: EnumConversionExperiment.Toggle with value On(true)
     due java.lang.IllegalAccessException: Class
     org.apache.camel.util.ObjectHelper can not access a member of class
     EnumConversionExperiment$Toggle with modifiers "public static"
          at
     
org.apache.camel.impl.converter.BaseTypeConverterRegistry.createTypeConversionException(BaseTypeConverterRegistry.java:667)
          at
     
org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:158)
          at
     
org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:129)
          at EnumConversionExperiment.main(EnumConversionExperiment.java:8)
     Caused by: org.apache.camel.RuntimeCamelException:
     java.lang.IllegalAccessException: Class
     org.apache.camel.util.ObjectHelper can not access a member of class
     EnumConversionExperiment$Toggle with modifiers "public static"
          at
     org.apache.camel.util.ObjectHelper.invokeMethod(ObjectHelper.java:1407)
          at
     
org.apache.camel.impl.converter.EnumTypeConverter.convertTo(EnumTypeConverter.java:51)
          at
     
org.apache.camel.impl.converter.OptimisedTypeConverter.convertTo(OptimisedTypeConverter.java:71)
          at
     
org.apache.camel.impl.converter.BaseTypeConverterRegistry.doConvertTo(BaseTypeConverterRegistry.java:300)
          at
     
org.apache.camel.impl.converter.BaseTypeConverterRegistry.convertTo(BaseTypeConverterRegistry.java:141)
          ... 2 more
     Caused by: java.lang.IllegalAccessException: Class
     org.apache.camel.util.ObjectHelper can not access a member of class
     EnumConversionExperiment$Toggle with modifiers "public static"
          at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102)
          at
     
java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:296)
          at
     java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:288)
          at java.lang.reflect.Method.invoke(Method.java:491)
          at
     org.apache.camel.util.ObjectHelper.invokeMethod(ObjectHelper.java:1405)
          ... 6 more

The type conversion process stops here instead of looking for custom
type converters. Line 53: return null; of EnumTypeConverter is never
reached. Would EnumTypeConverter indeed return null, the process would
continue and a custom converter would finally be called.

I'm pretty sure this is an issue. What do you think?

Regards,
Ralf


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