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native keyword in java
  • Difficulty Level : Medium
  • Last Updated : 07 Nov, 2019

The native keyword is applied to a method to indicate that the method is implemented in native code using JNI (Java Native Interface). native is a modifier applicable only for methods and we can’t apply it anywhere else. The methods which are implemented in C, C++ are called as native methods or foreign methods.

The main objectives of native keyword are:

  • To improve performance of the system.
  • To achieve machine level/memory level communication.
  • To use already existing legacy non-java code.

Pseudo code to use native keyword in java:

Class Native
        System.LoadLibrary(“Native library path”);
    Public native void m();
Class Test
    Public static void main(String[] args)
        Native n = new Native();

Important points about native keyword:

  • For native methods implementation is already available in old languages like C, C++ and we are not responsible to provide implementation. Hence native method declaration should end with ; (semi-colon).
  • We can’t declare native method as abstract.
  • We can’t declare native method as strictfp because there is no guarantee that old languages (C, C++) follow IEEE 754 standard. Hence native strictfp combination is illegal combination for methods.
  • The main advantage of native keyword is improvement in performance but the main disadvantage of native keyword is that it breaks platform independent nature of java.

Declaring Native Methods: In this section we explain how to declare a native method in Java and how to generate the corresponding C/C++ function prototype.

private native String getLine(String prompt);

From the Native Language Side:

javah -jni Prompt
JNIEXPORT jstring JNICALL Java_Prompt_getLine(JNIEnv *, jobject, jstring);


This article is contributed by Bishal Kumar Dubey. If you like GeeksforGeeks and would like to contribute, you can also write an article using or mail your article to See your article appearing on the GeeksforGeeks main page and help other Geeks.

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