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I am trying to pass a string value from java to c. And, a hashmap from C to java. I am trying to pass this using same method in C. But, I can't do that in a same method. I need the string data to fill my hashmap. So, I need to do it inside a single method. If I fill the hashmap(filling data locally) from C, it passes.

What I have tried:

Is it possible to pass data back and forth using the same method in C?
Updated 24-Jun-21 1:50am
Richard MacCutchan 24-Jun-21 6:11am    
Impossible to guess since we have no idea what your code is actually doing. Passing data between C and Java via JNI is quite straightforward, as long as you follow the rules.
15160877 24-Jun-21 6:39am    
I want to pass string to function(in C) which returns jobject.
public static native HashMap<string, string> displayString(java.lang.String value);
public static native HashMap<string, string> displayString();

I declared the native methods in java as above. The problem is C is not accepting the string and pass the hashmap at the same time.

My c function is like this:
JNIEXPORT jobject JNICALL Java_JavaNative_displayString(JNIEnv* env, jclass obj, jstring str) {
return jobject;
Richard MacCutchan 24-Jun-21 7:08am    
15160877 24-Jun-21 7:11am    
jobject is a hashmap. It works fine, that is why I didn't add the code. My c code reads the file,add it to hashmap and then returns it.
Richard MacCutchan 24-Jun-21 7:18am    
So what exactly is the problem?

1 solution

I have checked the JNI Documentation[^] and cannot see any support for HashMaps. You will need to use one of the supported types.
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15160877 24-Jun-21 7:51am    
Problem solved!!! Thank you

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