Was asked off-line for a zip-archive for convenience, hence I created a zip
archive and put it on
Dropbox. Here the link to get the zip-archive:
<https://www.dropbox.com/s/fti7camrb5hs7we/02-20180123-getPublicField.zip?dl=0>.
Just unzip, go
into the <02-20180123-getPublicField> directory and run (on Windows)
"1_compile.cmd", then either
"5a_module_compile_and_run_TestUse_mtest3_Class03A.cmd" or
"5b_classpath_compile_and_run_TestUse_mtest3_Class03A.cmd". Adapting the
scripts to Unix should be
straight forward.
Being formally an OpenJDK contributor there should be no legal problems.
---rony
On 23.01.2018 18:32, Rony G. Flatscher wrote:
> Oh, forgot the scripts to compile and run (these are under Windows):
>
> Assuming that the sources of "mod_A", "mod_B" and m"od_C" are located in
> "src", the compilation
> result should be placed into "out" here the compile script:
>
> rd out /s /q && md out
>
> @echo compiling module mod_A
> dir src\mod_A\*java /s /b > mod_A_source_files.txt
> type mod_A_source_files.txt
> javac -d out\mod_A @mod_A_source_files.txt
>
> @echo compiling module mod_B
> dir src\mod_B\*java /s /b > mod_B_source_files.txt
> type mod_B_source_files.txt
> javac --module-path out -d out\mod_B @mod_B_source_files.txt
>
> @echo compiling module mod_C
> dir src\mod_C\*java /s /b > mod_C_source_files.txt
> type mod_C_source_files.txt
> javac --module-path out -d out\mod_C @mod_C_source_files.txt
>
> Assuming that "TestUse_mtest3_Class03A.java" is located in the directory that
> contains the "out"
> subdirectory:
>
> del TestUse_mtest3_Class03A.class
> javac -cp "." --module-path out --add-modules mod_A,mod_B,mod_C
> TestUse_mtest3_Class03A.java
>
> java -cp "." --module-path out --add-modules mod_A,mod_B,mod_C
> TestUse_mtest3_Class03A
>
> ---rony
>
>
> On 23.01.2018 15:52, Rony G. Flatscher wrote:
>> Given three modules (sources at the end) where
>>
>> * "mod_A" exports its package "mtest1", to everyone
>> * "mod_B" requires "mod_A" and exports its package "mtest2" to "mod_C"
>> * "mod_C" requires "mod_B" and exports its package "mtest3" to everyone
>>
>> "mod_B"'s class "mtest2.Class02A" defines two public fields, one static
>> ("pubStaticFromClass02A")
>> and one an instance ("pubFromClass02") one.
>>
>> Compiling the modules and then using them in the following Java program (via
>> the CLASSPATH) works,
>> here the source:
>>
>> TestUse_mtest3_Class03A.java
>>
>> public class TestUse_mtest3_Class03A
>> {
>> public static void main (String args[]) {
>> mtest3.Class03A o=new mtest3.Class03A();
>> System.out.println("o.pubStaticFromClass02A :
>> "+o.pubStaticFromClass02A );
>> System.out.println("o.pubFromClass02A :
>> "+o.pubFromClass02A );
>> System.out.println("o: "+o+", o.getMyClassName():
>> "+o.getMyClassName());
>> }
>> }
>>
>> Compiling the above program and running it yields:
>>
>> o.pubStaticFromClass02A : static-mtest2.Class02A
>> o.pubFromClass02A : instance-mtest2.Class02A
>> o: mtest3.Class03A@5afa04c, o.getMyClassName(): via:
>> this=[mtest3.Class03A@5afa04c],
>> getMyClassName()=[class-mtest1.Class01A]
>>
>> Here is a 1:1 transcription from the above Java program to Rexx which uses
>> Java reflection to
>> achieve the same:
>>
>> test.rex
>>
>> o=.bsf~new("mtest3.Class03A") -- create Java object
>> say "o~pubStaticFromClass01A:" o~pubStaticFromClass02A
>> say "o~pubFromClass01A :" o~pubFromClass02A
>> say "o:" o "o~getMyClassName:" o~getMyClassName
>>
>> ::requires BSF.CLS -- direct interpreter to load Java bridge
>>
>> Running the Rexx program yields the following reflection error:
>>
>> // // -> -> RexxReflectJava9.processField(): EXCEPTION in GET-operation:
>> tmpField="pubStaticFromClass02A" exception:
>> "java.lang.IllegalAccessException: class
>> org.rexxla.bsf.engines.rexx.RexxReflectJava9 cannot access class
>> mtest2.Class02A (in module
>> mod_B) because module mod_B does not export mtest2 to unnamed module
>> @51c8530f"
>>
>> The reflection code currently
>>
>> * gets the type from the Java object ("mtest3.Class03A") and tests whether
>> the package "mtest3" is
>> exported (it is),
>> * looks for all declaredFields and finds none, so it gets the superclass
>> "mtest2.Class02A",
>> * looks for all declaredFields and locates the Field named
>> "pubStaticFromClass02A" and invokes the
>> Field's get method, supplying the Java object (an instance of class
>> mtest3.Class03A) which
>> causes an IlleagalAccessException.
>>
>> Although it is true that "mod_B" is not exported to the unnamed module it is
>> still the case that
>> "mod_C" is exported (and class "mtest3.Class03A" can be accessed), such that
>> all public members in
>> its superclasses should be accessible via reflection, even in the case that
>> a public member resides
>> in a module that is not exported to the reflector from the unnamed module?
>>
>> The reflective code would be able to assess that the supplied object is from
>> an exported type and
>> hence allow the get access in this case for reflected members in its
>> superclasses, like it seems the
>> Java compiler allows for.
>>
>> ---rony
>>
>> Here are the contents of the module directories in source:
>>
>>
>> ---------------------------------------------------------------------------
>>
>> mod_A/module-info.java
>>
>> module mod_A { exports mtest1; }
>>
>> mod_A/mtest1/Class01A.java
>>
>> package mtest1;
>>
>> abstract public class Class01A
>> {
>> protected static String myClassName =
>> "class-mtest1.Class01A";
>> }
>>
>>
>> ---------------------------------------------------------------------------
>>
>> mod_B/module-info.java
>>
>> module mod_B {
>> requires mod_A;
>> exports mtest2 to mod_C;
>> }
>>
>> mod_B/mtest2/Class02A.java
>>
>> package mtest2;
>>
>> public class Class02A extends mtest1.Class01A
>> {
>> public static String
>> pubStaticFromClass02A="static-mtest2.Class02A";
>> public String pubFromClass02A
>> ="instance-mtest2.Class02A";
>>
>> public String getMyClassName()
>> {
>> return "via: this=["+this+"],
>> getMyClassName()=["+myClassName+"]";
>> }
>> }
>>
>>
>> ---------------------------------------------------------------------------
>>
>> mod_C/module-info.java
>>
>> module mod_B {
>> requires mod_A;
>> exports mtest2 to mod_C;
>> }
>>
>> mod_C/mtest3/Class03A.java
>>
>> package mtest3;
>>
>> public class Class03A extends mtest2.Class02A
>> {
>> }
>>
>>
>> --------------------------------------------------------------------------
