Name: laC46010 Date: 01/24/97



Java doesn't allow to change value of final fields.
JNI functions of the kind Set<Type>Field behave different ways.

All other functions except SetObjectField don't change
a value of a final field. (Note that it would be good if they could
diagnose this violation somehow.)

SetObjectField function changes a value of a final field (See test below.)

To run the test, set environment variables JH (Java home) and CC (C compiler)
and run "jnirun" script.

> jnirun
Final int field has not been changed
Final Object field has been changed


::::::::::::::
jnirun
::::::::::::::
#!/usr/bin/csh

#setenv JH /export/ld32/jdk_1.1
#setenv CC /export/ld4/set/dist/sparc-S2/SC4.2/bin/cc

$JH/bin/javac -d . *.java
$CC -KPIC -G -I$JH/include -I$JH/include/solaris -o libtest.so *.c
setenv LD_LIBRARY_PATH ".:$LD_LIBRARY_PATH"
setenv CLASSPATH .
$JH/bin/java javasoft.sqe.tests.vm.sofl001.sofl00101.sofl00101
::::::::::::::
sofl00101.c
::::::::::::::
/* Ident: %Z%%M% %I% %E% */
/* Copyright %G% Sun Microsystems, Inc. All Rights Reserved */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "jni.h"

#ifdef __cplusplus
extern "C" {
#endif

#ifndef JNI_ENV_ARG
#ifdef __cplusplus
#define JNI_ENV_ARG(x,y) y
#define JNI_ENV_PTR(x) x
#else
#define JNI_ENV_ARG(x,y) x,y
#define JNI_ENV_PTR(x) (*x)
#endif
#endif

JNIEXPORT void JNICALL
Java_javasoft_sqe_tests_vm_sofl001_sofl00101_sofl00101_sofl00101
(JNIEnv *env, jobject obj, jint ival, jobject oval)
 {
jclass jc;
jfieldID jfi;

jc = JNI_ENV_PTR(env) -> GetObjectClass(JNI_ENV_ARG(env,obj));
jfi = JNI_ENV_PTR(env) -> GetFieldID(JNI_ENV_ARG(env,jc),"obj_f_fld","Ljava/lang/Object;");
JNI_ENV_PTR(env) -> SetObjectField(JNI_ENV_ARG(env,obj),jfi,oval);
jfi = JNI_ENV_PTR(env) -> GetFieldID(JNI_ENV_ARG(env,jc),"int_f_fld","I");
JNI_ENV_PTR(env) -> SetIntField(JNI_ENV_ARG(env,obj),jfi,ival);
 }
#ifdef __cplusplus
}
#endif
::::::::::::::
sofl00101.java
::::::::::::::
// Ident: %Z%%M% %I% %E%
// Copyright %G% Sun Microsystems, Inc. All Rights Reserved

package javasoft.sqe.tests.vm.sofl001.sofl00101;
import java.io.PrintStream;

public class sofl00101 {

  public final Object obj_f_fld = new char[12];
  public final int int_f_fld = 1;
  private static Object ob;

  public static void main(String argv[])
  {
    sofl00101 tob = new sofl00101();
    ob = "vv";
    tob.sofl00101(2, ob);
    if ( tob.int_f_fld == 2 ) {
      System.out.println("Final int field has changed");
    } else {
      System.out.println("Final int field has not changed");
    }
    if ( tob.obj_f_fld.equals(ob) ) {
      System.out.println("Final Object field has changed");
    } else {
      System.out.println("Final Object field has not changed");
    }
  }

  public native void sofl00101(int ival, Object oval);

  static {
    try {
      System.loadLibrary("test");
    } catch ( UnsatisfiedLinkError e ) {
      System.loadLibrary("jckjni");
    }
  }
}
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