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PORetrieving byte array of unknown length from Java store
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copied!<p>I already posted a question regarding it, but at that time I haven't have the account. I got a reply but I was still confused and I cannot continue on that thread.</p> <p>I am re posting the question again along with a link to previous conversation.</p> <p><a href="https://stackoverflow.com/questions/1227582/returning-char-array-from-java-to-c-jni/1231585#1231585">Returning char array from java to string - JNI</a></p> <p>The data I am storing in Java is serialized. I make a java function call using following piece of code.</p> <p>The following code assumes that char of C is compatible with byte of Java, because char of Java is of 2 bytes whereas char of C is of 1 byte. The jbyte is also a signed char*</p> <pre><code> //value will be the serialized data void store(char* key, char* value, int val_len) </code></pre> <p>{</p> <pre><code> //consider the jclass and methodid are already initialized jstring j_key = (*env)->NewStringUTF(env, key); jbyteArray j_value = (*env)->NewByteArray(env, val_len); (*env)->SetByteArrayRegion(env, j_value, 0, val_len, (jbyte *)value); //The store method on java side will save the value (as is) in memory (*env)->CallStaticVoidMethod(j_class, store_method, key, value); (*env)->ReleaseByteArrayElements(env, j_value, (jbyte *)value, JNI_ABORT); (*env)->ReleaseStringUTFChars(env, j_key, key); </code></pre> <p>}</p> <p>Once I have saved the data, I use another function to retrieve data from store. At that time i do not know the size of data I am going to retrieve. My API is in C and store is in Java. I will use my C functions to interact with Java. And also there can be multiple threads retrieving data from Java store at same time.</p> <p>I am making calls from C to Java and my control should return to C program after retrieving data. I am a little confuse on how the code will work. How will I get pointer to array (retrieved from java) and then retrieve it using GetByteArrayElements. Remember I dont know the size of data I am going to retrieve before hand and therefore cannot create a byte array using NewByteArray function and later fill it with data in java code.</p>

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