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Native Keyword In Java

Introduction 

In this article, we will learn about the native Keyword in Java. This Keyword is used to indicate that a method is implemented in platform-specific code, typically written in C or C++. When a method is marked as native, its implementation is provided by a dynamically linked library (DLL) or shared object (SO) file loaded at runtime. Using native methods is common when interfacing with system-level functionality, such as accessing hardware devices, interacting with operating system APIs, or working with performance-critical code. By using native methods, Java programs can leverage the power of platform-specific code while still enjoying the benefits of Java's object-oriented programming model.

What is a native keyword in Java?

The native Keyword indicates that a method is implemented in a platform-specific way, typically using code written in another programming language, such as C or C++. When a method is declared native, its implementation will not be provided in Java code but instead in a dynamically linked library (DLL) or shared library containing the platform-specific implementation. To use a native method, you must define the method signature in Java and then provide a platform-specific performance for the method in the form of a DLL or shared library. The native Keyword is commonly used for methods that interact with the operating system or other low-level resources, where the Java Virtual.   

When using native keywords in Java? 

In this statement, native keywords indicate that a method's implementation is provided by a platform-specific code rather than being written in Java. When a method is declared with the native Keyword, the method implementation is not provided in the current class or its superclass. The implementation is expected to be available in a dynamically linked library, which is platform-dependent. The method declaration with the native Keyword does not include a method body; instead, it is implemented in a language other than Java.

Typically, native methods are used to access system-level resources or to interact with hardware that cannot be accessed through pure Java code. Common examples of native methods in Java include file I/O, networking, and GUI libraries.

To use a native method, you must first define the method with the native Keyword in the Java code and then implement it in a separate file using the appropriate programming language for your platform. You then load the library that contains the implementation using the Java Native Interface (JNI) and call the method from your Java code.  

How to use native code in Java?  

Java is designed to be platform-independent, meaning it is not tightly integrated with the underlying operating System. However, there may be times when you need to use native code in your Java program, such as when you need to access system resources unavailable through Java's standard library.

To use native code in Java, you must create a Java Native Interface (JNI) that allows Java to interact with the native code. The JNI is a programming framework that allows Java code to call and be called by native applications or libraries in Java. 

Here are the general steps to use native code in Java using JNI

  1.  Create a header file (.h) that defines the functions that the native code exposes to Java.
  2.  Compile the native code into a dynamic-link library (DLL) or shared object file (SO).
  3.  Write the Java code that will call the native code and create a Java interface that matches the functions defined in the header file.
  4.  Compile the Java code into bytecode using the Java compiler.
  5.  Link the native library to the Java code using the Java Virtual Machine (JVM) or a separate linker.

Here is an example of using native code in Java 

public class demo    
{  
public static void main(String args[])   
{  
int a1 = 200, a2 = 110, sum;  
sum = a1 + a2;  
System.out.println("The sum of numbers is: "+sum);  
}  
}

Output 

 

Here is an example of using native code in C++ 

#include <iostream>

int main() {
    int a1 = 200, a2 = 110, sum;
    sum = a1 + a2;
    std::cout << "The sum of numbers is: " << sum << std::endl;
    return 0;
}

In C++, the main function does not require the parameter like in Java. Additionally, the System.out.println statement is replaced with std::cout in C++, and std::end1 is used to insert a new line. The return 0 statement at the end of the main function indicates successful program termination. 

4. Which is not a Java keyword native? 

This keyword "native" is a valid Java keyword, so the answer to your question is "not native." 

5. What is native memory in Java? 

In this statement, the term "native memory" refers to memory that is allocated outside of the Java Virtual Machine (JVM) heap. Unlike the Java heap, which is managed by the JVM's garbage collector, native memory is allocated and managed by the operating system directly.

Native memory is typically used to store data not managed by the Java heap, such as direct buffers, memory-mapped files, and native libraries. While native memory can offer performance benefits in certain situations, it also has drawbacks. For example, native memory is not subject to garbage collection, so it must be explicitly freed when it is no longer needed. Additionally, because native memory is managed by the operating system rather than the JVM, it can be more challenging to diagnose and fix issues related to native memory usage.

Conclusion 

This article taught us to learn the native keyword in Java.

FAQs 

Q- What is the "native" Keyword in Java?

A- The "native" Keyword in Java is used to declare a method implemented in native code, usually written in a language like C or C++. When a method is declared as native, it means that the implementation of the method is provided in a library that is not written in Java and is typically accessed through a platform-specific interface.

Q- Why would you use the "native" Keyword in Java?

A- You would use the "native" Keyword in Java when you need to access functionality that is not available in Java itself or when you need to access functionality that is specific to the platform you are running on. For example, you might use a native method to access low-level system resources or to interact with hardware devices.

Q- How do you implement a native method in Java?

A- To implement a native method in Java, you first declare the method using the "native" Keyword and provide a method signature that matches the native implementation. You then implement the method in a separate file written in the native language (such as C or C++), compile the file into a shared library, and load the library into your Java application using the "System.loadLibrary()" method.

Q- What are the potential drawbacks of using native methods in Java?

A- One potential drawback of using native methods in Java is that they can be platform-specific, which can make your code less portable. Additionally, because native methods bypass some of the safety features provided by the Java Virtual Machine (JVM), they can be more prone to errors and security vulnerabilities if not implemented carefully. Finally, using native methods requires more setup and maintenance than pure Java code, as you must compile and link the native code separately from your Java code.


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