How to return a char [][] from c++ to java with JNI

Question

hi , i am new to JNI and i am having some troubles with a special task :
in fact i am supposed to treat some data stored in a char[100][100] value and then return the result to java , the result is the sam value bur modified i mean a char [100][100] variable too...
i saw that we can rely on
JNIEXPORT jobjectArray JNICALL Java_JNITest_newArray (JNIEnv *env, jclass, jint size )
jobjectArray joa = ... );  // what in my case ?;
jsize len1 = (jsize)env->GetArrayLength(joa);
for (int i=0; i<l en1; i++)
jintArray colonne = (jintArray)env->GetObjectArrayElement(joa, i);
jsize len2 = (jsize)env->GetArrayLength(colonne);
jint *element = env->GetIntArrayElements(colonne, 0);
for(int j=0; j<len2; j++)
       jint res = element[j];
             // process some treatment here
        // how now to return the result to java : joa modified !!
[/code]
may be some errors present in this piece of code ...but i rely on your help to have the solution!! please i am really desperated !                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

Answer 1

You know that any JNI function for an array handles or creats only one-dimensional array. But if you know Java array structure then with these functions you can create Java arrays of any dimensions.
A Java multi-dimensional array is a set of nested one-dimensional arrays (consider dimensions from left to right). I give you only schema of this process. Let create the array of your type (for example, char [2][3]):
1) create one-dimensional object array "[C"[/b] of size two for the first dimension (and assign it to some variable of type jobjectArray) ;
2) create two three-dimentional char arrays and assign these local references to each element of the array created in prev. step;
3) fill each array created in (2) with your data (characters);
4) return to Java code the reference created in the step (1) and do not delete local references created in steps (1) and (2).