Book Image

Java Coding Problems - Second Edition

By : Anghel Leonard
Book Image

Java Coding Problems - Second Edition

By: Anghel Leonard

Overview of this book

The super-fast evolution of the JDK between versions 12 and 21 has made the learning curve of modern Java steeper, and increased the time needed to learn it. This book will make your learning journey quicker and increase your willingness to try Java’s new features by explaining the correct practices and decisions related to complexity, performance, readability, and more. Java Coding Problems takes you through Java’s latest features but doesn’t always advocate the use of new solutions — instead, it focuses on revealing the trade-offs involved in deciding what the best solution is for a certain problem. There are more than two hundred brand new and carefully selected problems in this second edition, chosen to highlight and cover the core everyday challenges of a Java programmer. Apart from providing a comprehensive compendium of problem solutions based on real-world examples, this book will also give you the confidence to answer questions relating to matching particular streams and methods to various problems. By the end of this book you will have gained a strong understanding of Java’s new features and have the confidence to develop and choose the right solutions to your problems.
Table of Contents (16 chapters)
1
Text Blocks, Locales, Numbers, and Math
Free Chapter
2
Objects, Immutability, Switch Expressions, and Pattern Matching
14
Other Books You May Enjoy
15
Index

144. Introducing Java Native Interface (JNI)

Java Native Interface (JNI) was the first Java API meant to act as a bridge between JVM bytecode and native code written in another programming language (typically C/C++).

Let’s suppose that we plan to call via JNI a C function on a Windows 10, 64-bit machine.

For instance, let’s consider that we have a C function for summing two integers called sumTwoInt(int x, int y). This function is defined in a C shared library named math.dll. Calling such functions from Java (generally speaking, functions implemented by native shared libraries) starts with loading the proper shared native library via System.loadLibrary(String library). Next, we declare the C function in Java via the native keyword. Finally, we call it with the following code:

package modern.challenge;
public class Main {
  static { 
    System.loadLibrary("math");
  }
  private native long sumTwoInt(int x, int y);
  public static void main(String...