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1. #JAVA 8 DOWNLOAD SOFTWARE#
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As a developer, you'll mostly work with the JDK and JVM, because those are the platform components you use to develop and run your Java programs.

#JAVA 8 DOWNLOAD SOFTWARE#

While there is a conceptual side to the JRE, in real-world practice it's just software installed on a computer, whose purpose is to run your Java programs. A layered architectural view shows that the JRE contains the JVM, class loader, and Java class libraries Installing and using the JRE From a package perspective, the JRE contains the JVM, as Figure 1 shows. In the layered view I just described, the JVM is created by the JRE.

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This important piece of software loads compiled Java code into memory and connects the code to the appropriate Java class libraries. As an example, the Java class loader is part of the Java Runtime Environment. The JRE contains libraries and software that your Java programs need to run. The JRE is the on-disk system that takes your Java code, combines it with the necessary libraries, and starts the JVM to execute it. It's a classic example of abstraction, abstracting the underlying operating system into a consistent platform for running Java applications.Ī Java Virtual Machine is a running software system responsible for executing live Java programs. In short, the JRE is a sort of meta-OS for Java programs. Automatic memory management is one of the JRE's most important services, ensuring that programmers don't have to manually control the allocation and reallocation of memory. The JRE smoothes over the diversity of operating systems, ensuring that Java programs can run on virtually any OS without modification. The Java Runtime Environment is a software layer that runs on top of a computer's operating system, providing additional services specific to Java. Each layer provides services that will be used (and required) by the layers above it.

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We can look at software as a series of layers that sit on top of the system hardware. When it was first introduced, Java's "write once, run anywhere" principle was considered revolutionary, but today it's been adopted as a norm for most software systems. The Java Runtime Environment changed all that, at least for Java programs. Resources in this case would be things like memory and program files and dependencies. The program ran inside whatever computer it was on, but relied on operating system settings for resource access. In the past, most software used the operating system (OS) as its runtime environment. The runtime environment loads class files and ensures there is access to memory and other system resources to run them. What is a runtime environment?Ī software program needs to execute, and to do that it needs an environment to run in. Defaults work well for most implementations, especially when you're starting out with Java.

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You also can download the JRE separately from the JDK, and you may choose from a variety of JVMs. We'll dig a lot deeper into how these components work together in the sections that follow.įrom an installation perspective, anytime you download a JDK, it will include a version-compatible JRE, and that JRE will include a default JVM.

I've previously introduced the JDK and JVM. In this quick tutorial, you'll learn about the JRE, which is the runtime environment for Java. Together, the Java Development Kit (JDK), the Java Virtual Machine (JVM), and the Java Runtime Environment (JRE) form a powerful trifecta of Java platform components for developing and running Java applications.