Java不允许我使用records。

huangapple
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英文:

Java is not letting me use records

问题

  1. 我正在运行 JDK 15（刚刚下载了它），并且在尝试使用记录（records）时遇到编译错误：
  3.     public class Runner {
  4.     
  5.     	// 这会导致编译错误
  6.         record Point(int x, int y) {}
  7.     
  8.     }

以下是我的 pom.xml 文件：

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <project xmlns="http://maven.apache.org/POM/4.0.0"
  3.          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  4.          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  5.     <modelVersion>4.0.0</modelVersion>
  7.     <groupId>something</groupId>
  8.     <artifactId>other-thing</artifactId>
  9.     <version>1.0.0-SNAPSHOT</version>
  11.     <properties>
  12.         <java.version>15</java.version>
  13.     </properties>
  15.     <build>
  16.         <plugins>
  17.             <plugin>
  18.                 <groupId>org.apache.maven.plugins</groupId>
  19.                 <artifactId>maven-compiler-plugin</artifactId>
  20.                 <version>3.8.1</version>
  21.                 <configuration>
  22.                     <source>${java.version}</source>
  23.                     <target>${java.version}</target>
  24.                 </configuration>
  25.             </plugin>
  26.         </plugins>
  27.     </build>
  29. </project>
  2. <details>
  3. <summary>英文:</summary>
  5. I&#39;m running JDK 15 (Just downloaded it) and I&#39;m getting a compile error when I try to use records:
  7.     public class Runner {
  8.     
  9.     	// This gives a compile error
  10.         record Point(int x, int y) {}
  11.     
  12.     }
  14. Here is my pom.xml:
  16.     &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
  17.     &lt;project xmlns=&quot;http://maven.apache.org/POM/4.0.0&quot;
  18.              xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;
  19.              xsi:schemaLocation=&quot;http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd&quot;&gt;
  20.         &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
  21.     
  22.         &lt;groupId&gt;something&lt;/groupId&gt;
  23.         &lt;artifactId&gt;other-thing&lt;/artifactId&gt;
  24.         &lt;version&gt;1.0.0-SNAPSHOT&lt;/version&gt;
  25.     
  26.         &lt;properties&gt;
  27.             &lt;java.version&gt;15&lt;/java.version&gt;
  28.         &lt;/properties&gt;
  29.     
  30.         &lt;build&gt;
  31.             &lt;plugins&gt;
  32.                 &lt;plugin&gt;
  33.                     &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
  34.                     &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
  35.                     &lt;version&gt;3.8.1&lt;/version&gt;
  36.                     &lt;configuration&gt;
  37.                         &lt;source&gt;${java.version}&lt;/source&gt;
  38.                         &lt;target&gt;${java.version}&lt;/target&gt;
  39.                     &lt;/configuration&gt;
  40.                 &lt;/plugin&gt;
  41.             &lt;/plugins&gt;
  42.         &lt;/build&gt;
  43.     
  44.     &lt;/project&gt;
  46. </details>
  49. # 答案1
  50. **得分**: 3
  52. 记录在Java 15中仍然是一个预览功能，因此在运行编译器时需要添加`--enable-preview`参数：
  54. ```xml
  55. <plugin>
  56.     <groupId>org.apache.maven.plugins</groupId>
  57.     <artifactId>maven-compiler-plugin</artifactId>
  58.     <version>3.8.1</version>
  59.     <configuration>
  60.         <source>${java.version}</source>
  61.         <target>${java.version}</target>
  62.         <compilerArgs>
  63.             <arg>--enable-preview</arg>
  64.         </compilerArgs>
  65.     </configuration>
  66. </plugin>
英文:

Records are still a preview feature in Java 15, so you will need to add the --enable-preview argument when running the compiler:

  1. &lt;plugin&gt;
  2.     &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
  3.     &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
  4.     &lt;version&gt;3.8.1&lt;/version&gt;
  5.     &lt;configuration&gt;
  6.         &lt;source&gt;${java.version}&lt;/source&gt;
  7.         &lt;target&gt;${java.version}&lt;/target&gt;
  8.         &lt;compilerArgs&gt;
  9.             &lt;arg&gt;--enable-preview&lt;/arg&gt;
  10.         &lt;/compilerArgs&gt;
  11.     &lt;/configuration&gt;
  12. &lt;/plugin&gt;

huangapple
  • 本文由 发表于 2020年9月29日 07:25:31
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