IntelliJ：error：java：error：不支持版本5

Question

我使用的是IntelliJ IDEA Ultimate 2019.3.1。每当我尝试启动任何简单的Java Maven项目（甚至可能是一个简单的Hello World）时，我都会得到以下错误：

Error:java: error: release version 5 not supported

通过终端运行java-version，得到以下输出：

openjdk 11.0.5 2019-10-15
OpenJDK Runtime Environment (build 11.0.5+10-post-Ubuntu-0ubuntu1.1)
OpenJDK 64-Bit Server VM (build 11.0.5+10-post-Ubuntu-0ubuntu1.1, mixed mode, sharing)

通过终端运行javac--version，得到以下输出：

javac 11.0.5

Error:(1, 26) java: package javafx.application does not exist
Error:(2, 20) java: package javafx.stage does not exist
Error:(4, 27) java: cannot find symbol
  symbol: class Application
Error:(12, 23) java: cannot find symbol
  symbol:   class Stage
  location: class Main
Error:(7, 9) java: cannot find symbol
  symbol:   method launch(java.lang.String[])
  location: class Main
Error:(11, 5) java: method does not override or implement a method from a supertype

Error:java: Source option 5 is no longer supported. Use 6 or later.

Answer 1

请参阅 ；https://stackoverflow.com/A/12900859/104891。

首先，在pom.xml中设置语言级别/发行版本，如下所示：

<properties>
  <maven.compiler.source>1.8</maven.compiler.source>
  <maven.compiler.target>1.8</maven.compiler.target>
</properties>

否则，Maven将默认值设置为1.5。如果还没有包含maven-compiler-plugin:

<dependency>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-compiler-plugin</artifactId>
  <version>3.8.1</version>
</dependency>