Trouble returning String from JNI method

Question

I'm a JNI newbie who is going through the SUN online book on JNI and have put together the 2nd program example (right after "helloworld"), but it is not working right. It is supposed to prompt you for a string, then returns the string that you type in. Right now it compiles without error, but it returns only the first word that I type, not the whole sentence. What am I doing wrong?
Here's the code:
Prompt.java
package petes.JNI;
public class Prompt
    private native String getLine(String prompt);
    static
        System.loadLibrary("petes_JNI_Prompt");
    public static void main(String[] args)
        Prompt p = new Prompt();
        String input = p.getLine("Type a line: ");
        System.out.println("User typed: " + input);
}petes_JNI_Prompt.h
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class petes_JNI_Prompt */
#ifndef _Included_petes_JNI_Prompt
#define _Included_petes_JNI_Prompt
#ifdef __cplusplus
extern "C" {
#endif
* Class:     petes_JNI_Prompt
* Method:    getLine
* Signature: (Ljava/lang/String;)Ljava/lang/String;
JNIEXPORT jstring JNICALL Java_petes_JNI_Prompt_getLine
  (JNIEnv *, jobject, jstring);
#ifdef __cplusplus
#endif
#endifpetes_JNI_Prompt.c
#include <jni.h>
#include <stdio.h>
#include "petes_JNI_Prompt.h"
JNIEXPORT jstring JNICALL Java_petes_JNI_Prompt_getLine
  (JNIEnv *env, jobject this, jstring prompt)
     char buf[128];
     const jbyte *str;
     str = (*env)->GetStringUTFChars(env, prompt, NULL);
     if (str == NULL)
          return NULL;  /*  OutOfMemoryError already thrown */
     printf("%s", str);
     (*env)->ReleaseStringUTFChars(env, prompt, str);
     // assume here that user will ty pe in 127 or less characters
     scanf("%s", buf);
     return (*env)->NewStringUTF(env, buf);
}Thanks in advance!
/Pete

Answer 1

OK, I have something that works now by substituting fgets for scanf. I have two other questions:
1) Do I need to free the memory created in buf? Will it allocate memory every time the method is run? Or will it allocate only once on creation, and so is no big deal?
2) A minor question: When I run this program in eclipse, the prompt string is displayed in the console only after the input string is entered and displayed. It works fine when I run it from the command line however. I have a feeling that this is a problem with how Eclipse deals with native methods and perhaps nothing I can fix. Any thoughts?
Thanks
Pete
Addendum, the updated code:
#include <jni.h>
#include <stdio.h>
#include "petes_JNI_Prompt.h"
JNIEXPORT jstring JNICALL Java_petes_JNI_Prompt_getLine
  (JNIEnv *env, jobject this, jstring prompt)
     char buf[128];
     const jbyte *str;
     str = (*env)->GetStringUTFChars(env, prompt, NULL);
     if (str == NULL)
          return NULL;  /*  OutOfMemoryError already thrown */
     printf("%s", str);
     (*env)->ReleaseStringUTFChars(env, prompt, str);
     //scanf("%s", buf);
     fgets(buf, 128, stdin);
     return (*env)->NewStringUTF(env, buf);
}Message was edited by:
petes1234