Convert JIntArray to Array of Object - arrays

Question

function Java_com_erm_controller_ARMReports_S35(PEnv: PJNIEnv; Obj: JObject; ex_UserRowID, ex_BSID : Integer; ex_RevalDate : JString;
ex_AFS, ex_HTM, ex_HFT : Boolean;
ex_IsMcCaulay_PNL: Boolean;
ex_Maturity, ex_Scale : JIntArray
): Integer; stdcall; export;
var objRpt : TARMReports;
I : Integer;
Len : JInt; //just a renamed delphi integer
aMaturity:array of Integer;
aScale:array of Integer;
begin
DLLErrorLog('CASH -S35');
objRpt := TARMReports.Create; JVM := TJNIEnv.Create(PEnv); ex_RevalDate_J := JVM.JStringToString(ex_RevalDate);
Len:=PEnv^.GetArrayLength(PEnv, ex_Maturity);
SetLength(aMaturity, Len);
Len:=PEnv^.GetArrayLength(PEnv, ex_Scale);
SetLength(aScale, Len);
DLLErrorLog('ex_Maturity Length'+ intToStr(Len));
for I := 0 to Len-1 do
begin
PEnv^.GetIntArrayRegion(PEnv, ex_Maturity, I, Len, #aMaturity[I]);
DLLErrorLog('ex_Maturity '+ IntToStr(aMaturity[I]));
PEnv^.GetIntArrayRegion(PEnv, ex_Scale, I, Len, #aScale[I]);
DLLErrorLog('ex_Scale '+ IntToStr(aScale[I]));
end;
Result := objRpt.S35(ex_UserRowID, ex_BSID, ex_RevalDate_J,
ex_AFS, ex_HTM, ex_HFT ,
ex_IsMcCaulay_PNL,
aMaturity, aScale
);
DLLErrorLog('CASH2 Ends -S35');
JVM.Free; objRpt.Free;
end;
Need to convert ex_Maturity, ex_Scale to objects to Delphi's Array of Integer.
Now while calling from Java it throws java.lang.ArrayIndexOutOfBoundsException
While printing in Log array values are getting . Please suggest us to work for me.

Answer 1

There are a couple of ways, depending on what, exactly your JIntArray is.
Firstly, if its an array of int (as in the primitive java type) then a get the length of the array via JNI, allocate a delphi array of integers and then get JNI to copy the data from the java array
Uses
AndroidAPI.JNI;
Var
Len:JNIInt; //just a renamed delphi integer
aMaturity:array of integer;
begin
Len:=PEnv^.GetArrayLength(PEnv, ex_Maturity);
//allocate the receiving array
SetLength(aMaturity, Len);
//now get the array data - note we are passing the address of the first element
//not the address of the array itself!
PEnv^.GetIntArrayRegion(PEnv, ex_Maturity, 0, Len, #aMaturity[0]);
//do stuff
end;
If you are dealing with an array of Integer (thats the Java class "Integer") then you need to get the array of objects from JNI one element at a time and use TJNIResolver to get the raw value;
Uses
AndroidAPI.JNI, AndroidAPI.JNIBridge;
Var
Len:JNIInt; //just a renamed delphi integer
Count:Integer;
Current:JNIObject;
CurrentValue:integer;
aMaturity:array of integer;
begin
Len:=PEnv^.GetArrayLength(PEnv, ex_Maturity);
//allocate the receiving array
SetLength(aMaturity, Len);
For Count:=0 to Len-1 do
begin
Current:=PEnv^.GetObjectArrayElement(PEnv, ex_Maturity, Count);
if assigned(Current) then
begin
CurrentValue:=TJNIResolver.GetRawValueFromJInteger(Current);
//Yes, you can inline this but the point is, here you do stuff with
//the element
aMaturity[Count]:=CurrentValue;
end;
end;
end;
Obviously the first method is much faster as crossing the JNI barrier is slow and you are only doing it once, whereas with the array of Java Integers you are doing it multiple times for each element.
You should also watch out for errors - I'm not checking for Java exceptions at any point which could crash and burn your app if you don't deal with them.
Edit : The OP has ready my answer and tried to work with it, which is nice. They have gotten a out of bounds exception in their code.
function Java_com_erm_controller_ARMReports_S35(PEnv: PJNIEnv; Obj: JObject; ex_UserRowID, ex_BSID : Integer; ex_RevalDate : JString;
ex_AFS, ex_HTM, ex_HFT : Boolean;
ex_IsMcCaulay_PNL: Boolean;
ex_Maturity, ex_Scale : JIntArray
): Integer; stdcall; export;
var objRpt : TARMReports;
I : Integer;
Len : JInt; //just a renamed delphi integer
aMaturity:array of Integer;
aScale:array of Integer;
begin
DLLErrorLog('CASH -S35');
objRpt := TARMReports.Create; JVM := TJNIEnv.Create(PEnv); ex_RevalDate_J := JVM.JStringToString(ex_RevalDate);
//you only have 1 length defined and possibly different array lengths
//process arrays seperately
Len:=PEnv^.GetArrayLength(PEnv, ex_Maturity);
SetLength(aMaturity, Len);
DLLErrorLog('ex_Maturity Length'+ intToStr(Len));
//only call this once, also watch the parameters you are passing in
PEnv^.GetIntArrayRegion(PEnv, ex_Maturity, 0, Len, #aMaturity[0]);
Len:=PEnv^.GetArrayLength(PEnv, ex_Scale);
SetLength(aScale, Len);
DLLErrorLog('ex_Scale Length'+ intToStr(Len));
PEnv^.GetIntArrayRegion(PEnv, ex_Scale, 0, Len, #aScale[0]);
Result := objRpt.S35(ex_UserRowID, ex_BSID, ex_RevalDate_J,
ex_AFS, ex_HTM, ex_HFT ,
ex_IsMcCaulay_PNL,
aMaturity, aScale
);
DLLErrorLog('CASH2 Ends -S35');
JVM.Free; objRpt.Free;
end;
What you were doing was getting the length twice, setting the delphi arrays correctly but then looping over them both in the same loop not taking into account that they could be different lengths. Your call to getinarrayregion was also passing the complete length in for aScale on the second parameter for both calls - if you really want to get each one in a loop like that then you need to pass the count and a length of 1 to only return 1 element - this is most likely what was causing the exception.
If you want to report the contents then create a procedure to do it, rather than using a loop inside your current procedure, you would have to copy and paste the loop to do it otherwise which is, franky bad coding practice and we don't want that now do we?
Sarcasm on
Not that expecting someone who has tried to help you to correct the your code rather than actually understanding the problem is any better, but ho hum.
Sarcasm off