Java native Keyword:

Purpose of ‘native’ Keyword

The primary purpose of using the ‘native’ keyword in Java is to enable interaction with system-level resources, hardware, or existing non-Java code libraries. These could include device drivers, operating system functions, or performance-critical algorithms that are already implemented in languages other than Java.

Usage of ‘native’ Keyword

1. Method Declaration: The ‘native’ keyword is used in method declarations to specify that the method's implementation is provided by native code.

public native void nativeMethod();

Here, nativeMethod is declared without a body, indicating that its implementation will be provided externally, typically in a native library.

2. Integration with Native Code: To use a native method in Java, you must provide a corresponding implementation in a native language (e.g., C, C++) and load it into the Java runtime environment using mechanisms like Java Native Interface (JNI).
3. Performance Optimization: native methods can be used to improve performance by leveraging optimized native code for specific tasks, especially those that require low-level access or complex computations.

Example

public class NativeExample {

// Declaration of native method
public native void sayHello();

// Load the native library that contains the implementation of nativeMethod
static {
    System.loadLibrary("NativeLibrary");
}

public static void main(String[] args) {
    NativeExample example = new NativeExample();
    example.sayHello(); // Call to native method
}
}