安装jdk时出现的问题不知道如何解决(语言-java)

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安装jdk时候出现了这个问题，不懂是什么意思，入门的蒻蒻一个，询求一下解决办法

  • 你可以参考下这个问题的回答, 看看是否对你有帮助, 链接: https://ask.csdn.net/questions/7653670
  • 你也可以参考下这篇文章：jdk切换版本问题，改了环境变量，java还是老版本问题解决
  • 你还可以看下java参考手册中的 java-集合 - 关于使用和扩展Java集合框架的课程。- 实现 描述了 JDK 的通用集合实现 并告诉你何时应使用哪种实现。 你还会了解到 封装器实现，它们为通用的 实现的功能。 -方便的实施
  • 除此之外, 这篇博客: 码农飞升记-05-JDK压缩包的下载安装方式以及环境变量的配置中的 Java SE 9 以及之后版本的发布节奏和不同版本的差距 部分也许能够解决你的问题, 你可以仔细阅读以下内容或跳转源博客中阅读:

  • 根据 Java Platform Group 产品管理高级总监 Donald Smith 在" Update and FAQ on the Java SE Release Cadence "中的描述以及 Oracle Java SE Support Roadmap 的描述，提炼出我们需要的部分：从 Java SE 9 开始 Java 开启了一个新的版本控制和发布节奏模型。

    Q1: Surely you can’t expect everyone to adopt major releases every six months?!

    There are no “major releases” per se any more; that is now a legacy term. Instead there is a steady stream of “feature releases.” This is consistent with how many releases have been done in the past, except with a new take on versioning. For example, Java 8 launched in March 2014. 8u20, a feature release, was released almost six months later in August. 8u40, the next feature release, was released almost six months after that.

    So yes, we expect an uptake of “feature releases” every six months, just as before.

    Going from Java 9->10->11 is closer to going from 8->8u20->8u40 than from 7->8->9. It’s scary to see at first when you’re used to major releases about every three years and have a mental model of the huge impact of those major changes. The six-month cadence is not that. Later in the FAQ we’ll provide more specific proof of this.

    Q2: If the new releases are basically the long standing six-month cadence, why rev the major release number each time? Why not just call it 9u20, 9u40, etc.?

    By having streamlined some JCP processes, it’s now possible to introduce new class library, JVM and language features such as Local-Variable Type Inference in just six months, instead of having to wait years for a “major release.” Rather than releasing dozens of large changes to the specifications every couple of years, they can be more pragmatically introduced in a steady stream as soon as they are ready for adoption.

    Q5: I’m still not convinced. Java 9 was a challenge to adopt, so that means 10 and 11 will be, too.

    Many Java SE developers and user have historically waited for a couple of updates before adopting a new “major version.” This could be expected when there were dozens of major new spec-changing features in a “major” release, but won’t be the case going forward with six-month releases. This has not been the case since Java SE 9.

    For example, the Java SE 9 release incorporated approximately 19,000 source code changes on top of Java SE 8. There were only 2,700 such changes between Java 9 and Java 10 – approximately the same as between Java 8 and Java 8u40. So while Java SE 9 was a “major” upgrade compared to Java SE 8, we have already seen that Java SE 10 is a simple feature update to Java SE 9.

    Q7: Ok, but I don’t want new features. I have a system in production and just want stability, performance and security updates only. What do I do?

    At Oracle, our intent is to designate releases every three years as “Long Term Support” (LTS) releases starting with Java SE 11 in September 2018. So while Java SE 9 has reached its End of Life with the release of Java 10, and Java 10 will do the same with the release of Java 11, Java 11 will have commercial support from Oracle available for at least eight additional years.

    As has happened for almost a decade with Java 6 and Java 7 (and likely Java 8 in 2019), once Oracle stops contributing our source code changes to a particular release series in OpenJDK, so that we can focus on the needs of our customers, other qualified contributors in the OpenJDK Community may step in to continue to maintain the release series. They do so in accordance with OpenJDK Community standards for as long as they choose, backporting the relevant changes from later releases still maintained by Oracle and others. For example, for JDK 6, Sun established the project in 2008, and Oracle continued to maintain it until 2013. Other maintainers then continued working on the project by backporting updates from later releases.

    Oracle supports such transitions in the OpenJDK Community by providing an established process for them to take place within the JDK Updates Project, as well as assistance to new maintainers to settle in their new roles, and last but not least, the Vulnerability Group.

    Oracle Java SE Product Releases

    Oracle provides Customers with Oracle Premier Support on Oracle Java SE products as described in the Oracle Lifetime Support Policy. For product releases after Java SE 8, Oracle will designate a release, every three years, as a Long-Term-Support (LTS) release. Java SE 11 is an LTS release. For the purposes of Oracle Premier Support, non‑LTS releases are considered a cumulative set of implementation enhancements of the most recent LTS release. Once a new feature release is made available, any previous non‑LTS release will be considered superseded. For example, Java SE 9 was a non‑LTS release and immediately superseded by Java SE 10 (also non‑LTS), Java SE 10 in turn is immediately superseded by Java SE 11. Java SE 11 however is an LTS release, and therefore Oracle Customers will receive Oracle Premier Support and periodic update releases, even though Java SE 12 was released.

  • 您还可以看一下 汤小洋老师的手把手搭建Java社团管理系统【附源码】（毕设）课程中的 环境搭建之安装JDK小节, 巩固相关知识点

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