TheJRE combines Java code created by using the JDK with the necessary libraries required to run it on a JVM and then creates an instance of the JVM that runs the resulting program. JVMs are available for multiple operating systems, and programs created with the JRE run on all of them. In this way, the Java Runtime Environment is what enables a Java program to run in any operating system without modification.
The JDK and JRE interact with one another to create a sustainable runtime environment that enables the seamless execution of Java-based applications in virtually any operating system. These attributes make up the JRE runtime architecture:
The Java ClassLoader dynamically loads all classes necessary to run a Java program. Since Java classes are only loaded into memory when they're required, the JRE uses ClassLoaders to automate this process on demand.
The bytecode verifier ensures the format and accuracy of Java code before it passes to the interpreter. If code violates system integrity or access rights, the class will be considered corrupted and won't be loaded.
Included as part of the JRE installation are deployment technologies like Java Web Start and Java plug-in that simplify the activation of applications and provide advanced support for future Java updates.
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The Java Runtime Environment (JRE) is software that Java programs require to run correctly. Java is a computer language that powers many current web and mobile applications. The JRE is the underlying technology that communicates between the Java program and the operating system. It acts as a translator and facilitator, providing all the resources so that once you write Java software, it runs on any operating system without further modifications.
A software program needs a runtime environment that provides access to memory and other system resources such as program files and dependencies. In the past, most software used the operating system directly as its runtime environment. However, this meant that developers had to write different code for each operating system that they wanted their applications to run on. The Java Runtime Environment (JRE) technology was created as a solution to this problem.
The JRE is actually one of three Java platform components that are required for any Java program to run successfully. The Java Development Kit (JDK) and Java Virtual Machine (JVM) are the other two components.
The JDK is a collection of software tools that you can use for developing Java applications. You can set up the JDK in your development environment by downloading and installing it. Select the JDK software version that matches the Java version you want to use. For example, Java Standard Edition, or Java SE, requires the Java SE JDK.
The JVM is software that runs the Java program line by line. Developers configure the JVM settings to manage program resources when the Java application runs. For example, you can change the JVM memory setting and check how much internal memory your Java applications use at runtime.
The JRE combines the Java code that you create by using the JDK with additional built-in code called libraries. It then creates a JVM instance, or local copy, that finally runs the Java programs. JVMs are available for multiple operating systems, and the JRE generates a single copy of your Java code that runs on all types of JVMs. In this way, the JRE facilitates platform independence for Java applications. You can write them once and run them anywhere.
The JDK is a software layer above the JRE that contains a compiler, a debugger, and other tools commonly found in any software development environment. You write code in English-like syntax in the JDK. The JDK compiles it and passes the byte code to the JRE. In contrast, the JRE contains class libraries, supporting files, and the JVM. It uses these software components to run the byte code on any device.
The Java Runtime Environment (JRE) runs on top of the operating system, providing additional Java-specific resources. The Java Development Kit (JDK) and JRE interact to create a sustainable runtime environment that runs Java program files on any machine. The JRE uses three core components to work.
Java class libraries contain collections of pre-written code that you can call as needed. They simplify the job of Java developers by providing built-in methods for common and non-trivial tasks such as taking input from users, displaying output to users, and more. All Java programs reference several class libraries. The Java ClassLoader dynamically loads all class files necessary into the Java Virtual Machine (JVM) on demand.
The JDK has a compiler that converts the English-like code you write into a machine language version called Java bytecode. They bytecode verifier in the JRE checks the format and accuracy of the Java code before loading it into the JVM. For example, if the code violates system integrity or access rights, the JRE will not load the class file.
The JRE includes technologies that simplify the process of releasing software changes to application users. These technologies also provide advanced support for updates in the application. Deployment technologies such as Java Web Start and Java plugin are included as part of the JRE installation. These technologies simplify the activation of applications and also provide advanced support for future updates to the JRE. The following are some examples:
The AWS Software Development Kit (SDK) for Java simplifies the use of AWS services by providing a set of libraries that are consistent and familiar for Java developers. It supports higher-level abstractions for simplified development. AWS focused open-source Java libraries are available along with code examples and a Java API reference guide.
The AWS SDK for Java 2.0 code examples on GitHub contain Java code examples and real-world use cases for AWS services to help accelerate the development of your applications. In addition, the AWS SDK for Java API Reference Guide describes the API operations for the latest version of the AWS SDK for Java. The reference guide also provides sample requests, responses, and errors for the supported web services protocols.
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