Passing parameter back and forth : JNI « Development Class « Java

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Java » Development Class » JNI 




Passing parameter back and forth
 
  
/**
   @version 1.10 1999-11-13
   @author Cay Horstmann
*/

#include "Employee.h"

#include <stdio.h>

JNIEXPORT void JNICALL Java_Employee_raiseSalary(JNIEnv* env, jobject this_obj, jdouble byPercent)
{  
   /* get the class */
   jclass class_Employee = (*env)->GetObjectClass(env, this_obj);

   /* get the field ID */
   jfieldID id_salary = (*env)->GetFieldID(env, class_Employee, "salary""D");

   /* get the field value */
   jdouble salary = (*env)->GetDoubleField(env, this_obj, id_salary);

   salary *= + byPercent / 100;

   /* set the field value */
   (*env)->SetDoubleField(env, this_obj, id_salary, salary);
}



////

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 @version 1.10 1999-11-13
 @author Cay Horstmann
 */

public class Employee
{
   public Employee(String n, double s)
   {
      name = n;
      salary = s;
   }

   public native void raiseSalary(double byPercent);

   public void print()
   {
      System.out.println(name + " " + salary);
   }

   private String name;
   private double salary;

   static
   {
      System.loadLibrary("Employee");
   }
}



////

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 @version 1.10 1999-11-13
 @author Cay Horstmann
 */

public class EmployeeTest
{
   public static void main(String[] args)
   {
      Employee[] staff = new Employee[3];

      staff[0new Employee("Harry Hacker"35000);
      staff[1new Employee("Carl Cracker"75000);
      staff[2new Employee("Tony Tester"38000);

      for (Employee e : staff)
         e.raiseSalary(5);
      for (Employee e : staff)
         e.print();
   }
}




   
  














JNIParameterTest.zip( 2 k)
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