Re: ILERPG call to Java get list fails and generates core dump

Thanks Scott,

I am not a java programmer so some of the terms and confusing so I asked a
java guy to explain and this is what he said ...

For example the method getFirst in class
com.braintreegateway.ResourceCollection has the following declaration in
Eclipse:

public T getFirst()

As far as the Java runtime is concerned, T is equivalent to
java.lang.Object, thus its real signature is

public java.lang.Object getFirst();

Java is clever enough to automatically cast the return object to the
object specified by the type ‘T’. In this case T is
com.braintreegateway.Transaction. The type is specified when
ResourceCollection is constructed eg ResourceCollection c = new
ResourceCollection<Transaction>().

This is what is meant by Java generics.

In RPG, to call getFirst, the method prototype is something like

getFirst PROC
CLASS(‘java.lang.Object’:’com.braintreegateway.ResourceCollection’:’getFirst’)

The return type is something like

transactionJ CLASS(‘com.braintreegateway.Transaction’)

Now is RPG going to be clever enough to ‘cast’ java.lang.Object into
com.braintreegateway.Transaction?

Remember Java does this step automatically.



Appreciate any comments

Thank you


Don Brown





From: Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>
To: "RPG programming on the IBM i (AS/400 and iSeries)"
<rpg400-l@xxxxxxxxxxxx>
Date: 11/01/2017 02:03 AM
Subject: Re: ILERPG call to Java get list fails and generates core
dump
Sent by: "RPG400-L" <rpg400-l-bounces@xxxxxxxxxxxx>



Don,

If by "generic object" you mean "java.lang.Object", yes, you can receive
it in RPG and pass it to other Java routines. Its no different from any
other Java object.

You say that the object is 0... I believe this is the same as *NULL, so
it is returning a null object. If that is not expected, then you need
to determine why that is happening.

-SK



On 1/9/2017 8:55 PM, Don Brown wrote:

(This is cross posted on java400-l)

With some advice from Jon ...

I have now generated all the prototypes using the Rdi wizard.

We have corrected the creation of the java calendar object and now can
convert the java object to a string and check the calendar values which
are now correct.

Two steps forward and then one step backwards.

We are now calling a class that returns a generic java object. The call
completes without error but the java object returned has a value of 0

and

any attempt to use that object fails.

Can a class that returns a generic object be used in RPG ?

I am also struggling to get any debug information from the java calls.
(Will open a pmr with IBM if I can't find any other way to get any
logging)

I have done the following but there is noting in the stdout or errout
files.

ADDENVVAR QIBM_RPG_JAVA_PROPERTIES

VALUE('-Dos400.stdout=file:/home/sttapp100r.txt;-Dos400.stderr=file:/home/sttapp100r.err.txt;')

ADDENVVAR QIBM_USE_DESCRIPTOR_STDIO VALUE('Y')

call CHECKSTDIO (This is the IBM documented program to open the output
files)
See:

http://www.ibm.com/developerworks/rational/cafe/docBodyAttachments/2681-102-2-7220/Troubleshooting_RPG_Calls_To_Java_v2.html#stdout

Cheers

Don


Don Brown

MSD Information Technology

Suite 5/29 McDougall Street Milton Q 4064
( 07 3368 7888
+ PO Box 1629 MILTON Q 4054
Ê 07 3368 7877
* Don.Brown@xxxxxxxxxx
È 0408 751 644
þ www.msd.net.au www.architect4web.com.au





I am a proud supporter of THE REFERRAL NETWORK and recommend the

services

of the other member businesses. For more information please checkout the
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From: Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>
To: "RPG programming on the IBM i (AS/400 and iSeries)"
<rpg400-l@xxxxxxxxxxxx>
Date: 07/01/2017 09:04 AM
Subject: Re: ILERPG call to Java get list fails and generates

core

dump
Sent by: "RPG400-L" <rpg400-l-bounces@xxxxxxxxxxxx>



Don,

Looks to me like you are doing the right thing in your example... I
misread the earlier message as saying that the class was java.util.List.
My mistake.

See, I knew I was asking a stupid question :-)

-SK



On 1/5/2017 4:45 PM, Don Brown wrote:

Forgive me but I am confused with your question and your question is
definitely not stupid.

My java skills are very, very poor and trial and error are my teacher.

I am trying to return an object into listIdJ using the method getIds on
java object result.

listIdJ = getIds(result);

The prototype for getIds is;

D getIds PR O ExtProc(*JAVA:
D 'com.braintreegateway.-
D ResourceCollection':'getIds')
D Class(*JAVA:'java.util.List')

So my understanding is for the ExtProc(*Java ... that you specify

the

class as the first parameter and the method as the second.

From the results of;

javap -s com.braintreegateway.ResourceCollection

Compiled from "ResourceCollection.java"
public class com.braintreegateway.ResourceCollection extends
java.lang.Object implements java.lang.Iterable{
public

com.braintreegateway.ResourceCollection(com.braintreegateway.Pager,

com.braintreegateway.util.NodeWrapper);
Signature:
(Lcom/braintreegateway/Pager;Lcom/braintreegateway/util/NodeWrapper;)V
public int getMaximumSize();
Signature: ()I
public java.util.Iterator iterator();
Signature: ()Ljava/util/Iterator;
public java.lang.Object getFirst();
Signature: ()Ljava/lang/Object;
public java.util.List getIds();
Signature: ()Ljava/util/List;
static java.util.List

access$000(com.braintreegateway.ResourceCollection);

Signature:

(Lcom/braintreegateway/ResourceCollection;)Ljava/util/List;

If I change the prototype as follows I get an error that the method is

not

found when I run the program;

D getIds PR O ExtProc(*JAVA:
D 'com.braintreegateway.-
D ResourceCollection':'getIds')
D Class(*java:'com.braintreegateway.-
D ResourceCollection')

I have defined the receiving java object (listIdJ) as follows;

D listIdJ S O Class(*JAVA:'java.util.List')


If I open the jar file in eclipse and expand the
com.braintreegateway.resourceCollection.class I can get the following
signature details.

// Compiled from ResourceCollection.java (version 1.5 : 49.0, super

bit)

// Signature:
<T:Ljava/lang/Object;>Ljava/lang/Object;Ljava/lang/Iterable<TT;>;
public class com.braintreegateway.ResourceCollection implements
java.lang.Iterable {

// Field descriptor #22 Ljava/util/List;
// Signature: Ljava/util/List<Ljava/lang/String;>;
private java.util.List ids;

// Field descriptor #26 Lcom/braintreegateway/Pager;
// Signature: Lcom/braintreegateway/Pager<TT;>;
private com.braintreegateway.Pager pager;

// Field descriptor #29 I
private int pageSize;

// Method descriptor #31
(Lcom/braintreegateway/Pager;Lcom/braintreegateway/util/NodeWrapper;)V
// Signature:

(Lcom/braintreegateway/Pager<TT;>;Lcom/braintreegateway/util/NodeWrapper;)V

// Stack: 3, Locals: 3
public ResourceCollection(com.braintreegateway.Pager pager,
com.braintreegateway.util.NodeWrapper response);
0 aload_0 [this]
1 invokespecial java.lang.Object() [4]
4 aload_0 [this]
5 aload_1 [pager]
6 putfield com.braintreegateway.ResourceCollection.pager :
com.braintreegateway.Pager [1]
9 aload_0 [this]
10 aload_2 [response]
11 ldc <String "page-size"> [5]
13 invokevirtual
com.braintreegateway.util.NodeWrapper.findInteger(java.lang.String) :
java.lang.Integer [6]
16 invokevirtual java.lang.Integer.intValue() : int [7]
19 putfield com.braintreegateway.ResourceCollection.pageSize : int
[2]
22 aload_0 [this]
23 aload_2 [response]
24 ldc <String "ids/*"> [8]
26 invokevirtual
com.braintreegateway.util.NodeWrapper.findAllStrings(java.lang.String)

:

java.util.List [9]
29 putfield com.braintreegateway.ResourceCollection.ids :
java.util.List [3]
32 return
Line numbers:
[pc: 0, line: 74]
[pc: 4, line: 75]
[pc: 9, line: 76]
[pc: 22, line: 77]
[pc: 32, line: 78]
Local variable table:
[pc: 0, pc: 33] local: this index: 0 type:
com.braintreegateway.ResourceCollection
[pc: 0, pc: 33] local: pager index: 1 type:
com.braintreegateway.Pager
[pc: 0, pc: 33] local: response index: 2 type:
com.braintreegateway.util.NodeWrapper
Local variable type table:
[pc: 0, pc: 33] local: this index: 0 type:
com.braintreegateway.ResourceCollection<T>
[pc: 0, pc: 33] local: pager index: 1 type:
com.braintreegateway.Pager<T>

// Method descriptor #43 ()I
// Stack: 1, Locals: 1
public int getMaximumSize();
0 aload_0 [this]
1 getfield com.braintreegateway.ResourceCollection.ids :
java.util.List [3]
4 invokeinterface java.util.List.size() : int [10] [nargs: 1]
9 ireturn
Line numbers:
[pc: 0, line: 86]
Local variable table:
[pc: 0, pc: 10] local: this index: 0 type:
com.braintreegateway.ResourceCollection
Local variable type table:
[pc: 0, pc: 10] local: this index: 0 type:
com.braintreegateway.ResourceCollection<T>

// Method descriptor #45 ()Ljava/util/Iterator;
// Signature: ()Ljava/util/Iterator<TT;>;
// Stack: 4, Locals: 1
public java.util.Iterator iterator();
0 new com.braintreegateway.ResourceCollection$PagedIterator [11]
3 dup
4 aload_0 [this]
5 aload_0 [this]
6 invokespecial

com.braintreegateway.ResourceCollection$PagedIterator(com.braintreegateway.ResourceCollection,

com.braintreegateway.ResourceCollection) [12]
9 areturn
Line numbers:
[pc: 0, line: 90]
Local variable table:
[pc: 0, pc: 10] local: this index: 0 type:
com.braintreegateway.ResourceCollection
Local variable type table:
[pc: 0, pc: 10] local: this index: 0 type:
com.braintreegateway.ResourceCollection<T>

// Method descriptor #48 ()Ljava/lang/Object;
// Signature: ()TT;
// Stack: 4, Locals: 1
public java.lang.Object getFirst();
0 aload_0 [this]
1 getfield com.braintreegateway.ResourceCollection.pager :
com.braintreegateway.Pager [1]
4 aload_0 [this]
5 getfield com.braintreegateway.ResourceCollection.ids :
java.util.List [3]
8 iconst_0
9 iconst_1
10 invokeinterface java.util.List.subList(int, int) :

java.util.List

[13] [nargs: 3]
15 invokeinterface

com.braintreegateway.Pager.getPage(java.util.List)

: java.util.List [14] [nargs: 2]
20 iconst_0
21 invokeinterface java.util.List.get(int) : java.lang.Object [15]
[nargs: 2]
26 areturn
Line numbers:
[pc: 0, line: 94]
Local variable table:
[pc: 0, pc: 27] local: this index: 0 type:
com.braintreegateway.ResourceCollection
Local variable type table:
[pc: 0, pc: 27] local: this index: 0 type:
com.braintreegateway.ResourceCollection<T>

// Method descriptor #51 ()Ljava/util/List;
// Signature: ()Ljava/util/List<Ljava/lang/String;>;
// Stack: 1, Locals: 1
public java.util.List getIds();
0 aload_0 [this]
1 getfield com.braintreegateway.ResourceCollection.ids :
java.util.List [3]
4 areturn
Line numbers:
[pc: 0, line: 98]
Local variable table:
[pc: 0, pc: 5] local: this index: 0 type:
com.braintreegateway.ResourceCollection
Local variable type table:
[pc: 0, pc: 5] local: this index: 0 type:
com.braintreegateway.ResourceCollection<T>

// Method descriptor #54
(Lcom/braintreegateway/ResourceCollection;)Ljava/util/List;
// Stack: 1, Locals: 1
static synthetic java.util.List
access$000(com.braintreegateway.ResourceCollection x0);
0 aload_0 [x0]
1 getfield com.braintreegateway.ResourceCollection.ids :
java.util.List [3]
4 areturn
Line numbers:
[pc: 0, line: 16]
Local variable table:
[pc: 0, pc: 5] local: x0 index: 0 type:
com.braintreegateway.ResourceCollection

// Method descriptor #57 (Lcom/braintreegateway/ResourceCollection;)I
// Stack: 1, Locals: 1
static synthetic int

access$100(com.braintreegateway.ResourceCollection

x0);
0 aload_0 [x0]
1 getfield com.braintreegateway.ResourceCollection.pageSize : int

[2]

4 ireturn
Line numbers:
[pc: 0, line: 16]
Local variable table:
[pc: 0, pc: 5] local: x0 index: 0 type:
com.braintreegateway.ResourceCollection

// Method descriptor #59
(Lcom/braintreegateway/ResourceCollection;)Lcom/braintreegateway/Pager;
// Stack: 1, Locals: 1
static synthetic com.braintreegateway.Pager
access$200(com.braintreegateway.ResourceCollection x0);
0 aload_0 [x0]
1 getfield com.braintreegateway.ResourceCollection.pager :
com.braintreegateway.Pager [1]
4 areturn
Line numbers:
[pc: 0, line: 16]
Local variable table:
[pc: 0, pc: 5] local: x0 index: 0 type:
com.braintreegateway.ResourceCollection

Inner classes:
[inner class info: #11
com/braintreegateway/ResourceCollection$PagedIterator, outer class

info:

#16 com/braintreegateway/ResourceCollection
inner name: #19 PagedIterator, accessflags: 2 private]


Don Brown

MSD Information Technology

Suite 5/29 McDougall Street Milton Q 4064
( 07 3368 7888
+ PO Box 1629 MILTON Q 4054
Ê 07 3368 7877
* Don.Brown@xxxxxxxxxx
È 0408 751 644
þ www.msd.net.au www.architect4web.com.au





I am a proud supporter of THE REFERRAL NETWORK and recommend the

services

of the other member businesses. For more information please checkout

the

website www.refnet.net.au





From: Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>
To: "RPG programming on the IBM i (AS/400 and iSeries)"
<rpg400-l@xxxxxxxxxxxx>
Date: 06/01/2017 07:32 AM
Subject: Re: ILERPG call to Java get list fails and generates

core

dump
Sent by: "RPG400-L" <rpg400-l-bounces@xxxxxxxxxxxx>



Don,

Forgive me if this is a stupid question, but... You told us the

method

was "java.util.List getIds()". But you appear to be calling
"com.braintreegateway.ResourceCollection getIds()".

So... why don't these match? Is there more than one getIds() method?
If so, can you show us the signature et al for the braintree one so

that

we can see the signature for the one you're trying to call?

-SK





On 1/5/2017 3:08 AM, Don Brown wrote:

I am hoping someone can point me in the right direction with this one.

Java is crashing when I use a method that should return a java list
object..

I checked the class using the javap -s command in qsh I get the

details

about the class; (All class details from this are included below)

The method I am using is gstIds
public java.util.List getIds();
Signature: ()Ljava/util/List;

I have the prototype defined in my program as follows;

D getIds PR O ExtProc(*JAVA:
D 'com.braintreegateway.-
D ResourceCollection':'getIds')
D Class(*JAVA:'java.util.List')

D listIdJ S O Class(*JAVA:'java.util.List')

The following code snippet precedes the error but running in debug all
statements complete normally

// Create search request
transReqJ = transReqC();
dateParamsJ = dateParams(transReqJ);
transreqJ = setRange(dateParamsJ: startJ: endJ);
transGatewayJ = transGateway(gateway);

// Retrieve the transactions
result = search(transGatewayJ: transReqJ);

When the following line is executed it results in a gpf and system

dump.

There is a stack trace showing on the screen but is meaningless to me

-

See below.

listIdJ = getIds(result);

The joblog shows error MSG:RNX0301 Java exception received when

calling

Java method.
Cause . . . . . : RPG procedure STTAPP100R in program

XAPSW/STTAPP100R

received Java exception "**UNKNOWN ERROR**" when calling method

"getIds"

with signature "()Ljava.util.List;" in class
"com.braintreegateway.ResourceCollection".


Results from javap -s

javap -s com.braintreegateway.ResourceCollection

The java.version property was detected as input. This property is used

as

output only and has no effect on JVM initialization.
Compiled from "ResourceCollection.java"
public class com.braintreegateway.ResourceCollection extends
java.lang.Object implements java.lang.Iterable{
public

com.braintreegateway.ResourceCollection(com.braintreegateway.Pager,

com.braintreegateway.util.NodeWrapper);
Signature:
(Lcom/braintreegateway/Pager;Lcom/braintreegateway/util/NodeWrapper;)V

public int getMaximumSize();
Signature: ()I
public java.util.Iterator iterator();
Signature: ()Ljava/util/Iterator;
public java.lang.Object getFirst();
Signature: ()Ljava/lang/Object;
public java.util.List getIds();
Signature: ()Ljava/util/List;
static java.util.List

access$000(com.braintreegateway.ResourceCollection);

Signature:

(Lcom/braintreegateway/ResourceCollection;)Ljava/util/List;

Stack Trace from screen when error occurs

----------- Stack Backtrace -----------
gpProtectedRunCallInMethod+0x24 (0xD07F3BC0 [libj9vm24.so+0x15bc0])
signalProtectAndRunGlue+0x14 (0xD080F090 [libj9vm24.so+0x31090])
j9sig_protect+0x138 (0xD0872F54 [libj9prt24.so+0x1f54])
gpProtectAndRun+0xc4 (0xD080F19C [libj9vm24.so+0x3119c])
gpCheckCallin+0x44 (0xD07F4398 [libj9vm24.so+0x16398])
callVirtualObjectMethodA+0x38 (0xD07F8538 [libj9vm24.so+0x1a538])
J9_i5OS_CallObjectMethodA+0xac (0xD054C8B0 [libi5osenv.so+0xd8b0])
(0x000036F0)


Don Brown