Java First Lesson: introduction

Java language Overview:

• is a high-level programming language introduced by Sun (Stanford University Network, Stanford University web Company) in 1995;
• is an Internet-facing programming language;
• As Java technology continues to mature in the web, it has become the preferred development language for Web applications
• Is easy to learn, fully object-oriented, safe and reliable, platform-independent programming language

Three technical architectures for the Java language:

JAVA EE

JAVA SE

JAVA ME

Features of the Java language:

What is cross-platform?

Applications written in the Java language can be run on different system platforms

What is the principle?

Just install a Java Virtual machine (JVM JAva Virtual Machine) on the operating system that needs to run the Java application. A JVM is responsible for the operation of the Java program in the system.

Graphic:

Because of the JVM, the same Java program can be executed in three different operating systems. This realizes the cross-platform of the Java program. Also known as Java has good portability.

Building the Java Environment:

JRE (JAva Runtime Environment

Java Runtime Environment)

Including the core class libraries required for Java virtual machines and Java programs, if you want a well-developed Java program, you only need to install the JRE on your computer.

JDK (JAva Development Kit)

Java Development Toolkit

The JDK is available to Java developers, which includes Java development tools and the JRE. So with the JDK installed, there is no need to install the JRE separately.

Development tools: Compilation Tools (Javac.ext) packaging Tools (Jar.ext), etc.

In a nutshell: Java programs developed with the JDK are delivered to the JRE to run.

Java First Lesson: introduction