Access hashmap elements

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C

Java

JNI

I have passed a hashmap from java to C. Now, I need to fill the hashmap and pass it back to java. This is my java code.
Main.java

import java.util.*;



public class Main {
	static {
		System.loadLibrary("Tests");	}

	    public void doProcess() {

	        Container container = new Container();
	        container.getParameterMap().put("foo","bar");

	        service(container);
	    }

	    public native void service(Container container);

   
	public static void main(String args[])
	{
	<pre>System.out.println("Service Names");
	   HashMap<String,String>[] h =  new HashMap().service();
	for(int i=0;;i++)
	  {
	      
		  System.out.print(h+"\n");
		
	  }

}

}

Container.java

import java.util.HashMap;
import java.util.Map;

public class Container {
	 private String hello;
	    private Map<String, String> parameterMap = new HashMap<String, String>();

	    public Map<String, String> getParameterMap() {
	        return parameterMap;
	    }
}

Now, how can I access and fill the hashmap and pass it back to java.

What I have tried:

I have tried getting hashmap in C using the following code.

jclass c_Container = (*env)->GetObjectClass(env, jContainer);

   jmethodID m_GetParameterMap = (*env)->GetMethodID(env, c_Container, "getParameterMap", "()Ljava/util/Map;");

   jobject jParameterMap = (*env)->CallObjectMethod(env, jContainer, m_GetParameterMap);


   jclass c_Map =(*env)->FindClass(env,"java/util/Map");

jmethodID put = (*env)->GetMethodID(env,c_Map, "put", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;");

   jmethodID m_GetSize = (*env)->GetMethodID(env, c_Map, "size", "()I");


   int jSize = (*env)->CallIntMethod(env, jParameterMap, m_GetSize);
               char* key = (char*)"*";
             char* val = (char*)"";
            (*env)->CallObjectMethod(jParameterMap, put, key, val);

Now, can I access the hashmap and update the data and send it back.

Is there any in-built method does hashmap have to do this?