此语言级别不支持 Java- Diamond 类型
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/44005097/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Java- Diamond types are not supported at this language level
提问by Noble-Surfer
I have just started working on a Java project, and have downloaded the source code from GitHub, using IntelliJ- I have never used IntelliJ before, but am told that it is a much better IDE to use than Eclipse (which is what I was using when I last did any Java development- about four years ago).
我刚刚开始处理一个 Java 项目，并使用 IntelliJ 从 GitHub 下载了源代码 - 我以前从未使用过 IntelliJ，但被告知它是一个比 Eclipse 更好的 IDE（这是我使用的当我上次进行任何 Java 开发时 - 大约四年前）。
When I try to build the source locally on my computer, having pulled the latest working version from GitHub, I get a compile error on several different lines of code- the error says:
当我尝试在我的计算机上本地构建源代码时，从 GitHub 中提取了最新的工作版本，我在几行不同的代码中遇到编译错误 - 错误说：
Error:(27, 34) java: diamond operator is not supported in -source 1.5 (use -source 7 or higher to enable diamond operator)
错误：(27, 34) java: -source 1.5 不支持菱形运算符（使用 -source 7 或更高版本启用菱形运算符）
and the lines where these compile errors appear, are lines like:
出现这些编译错误的行是这样的：
return new ArrayList<>(0);
If I select the line, and do Alt + Enteron the error, it shows a message stating that I can
如果我选择该行，并Alt + Enter针对错误执行操作，则会显示一条消息，说明我可以
"Set language level to 7- Diamonds, ARM, Multi-cache, etc"
“将语言级别设置为 7-Diamonds、ARM、Multi-cache 等”
However, if I select this option, nothing happens...
但是，如果我选择此选项，则没有任何反应...
In the pom.xmlfile, there is the following xml:
在pom.xml文件中，有以下xml：
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-source-plugin</artifactId>
<version>${maven-source-plugin.version}</version>
<executions>
<execution>
<id>attach-sources</id>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
But when I looked this error up, I came across the answer at: Diamond type are not supported at this language level, which indicated that I should be using maven1.7 or higher- and it appears that the project is already using version 1.8, so I don't understand why I'm getting this compile error...
但是当我查看这个错误时，我发现答案是：Diamond type are not supported at this language level，这表明我应该使用 maven1.7 或更高版本 - 并且该项目似乎已经在使用版本 1.8，所以我不明白为什么我会收到这个编译错误......
Anyone have any suggestions?
有人有什么建议吗？
回答by user8936069
Add the following code into your pom.xmlfile.
将以下代码添加到您的pom.xml文件中。
<!-- maven-compiler-plugin -->
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.7.0</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
回答by DrLime2k10
Under File->Project Structure(Ctrl+ Alt+ Shift+ s) there's a section called Project Settings, and Project
在File->Project Structure( Ctrl+ Alt+ Shift+ s) 下有一个名为 的部分Project Settings，并且Project
Here you can set the project language level.
您可以在此处设置项目语言级别。
