问题描述
VisualStudioCode需要openJDK11，但我需要使用1.8版进行编译。
我下载了openJDK11并更改了JAVA_HOME变量，但是当我运行java -version命令时，它仍然显示Java 1.8已安装：
C:\>java -version
java version "1.8.0_261"
Java(TM) SE Runtime Environment (build 1.8.0_261-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.261-b12,mixed mode)
C:\>javac -version
javac 11.0.2
然后：
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ User ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 21 source files to C:\1-ROOT\user\target\classes
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 9.036 s
[INFO] Finished at: 2020-09-07T10:26:36-03:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project User: Fatal error compiling: CompilerException: NullPointerException -> [Help 1]
org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project User: Fatal error compiling
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:566)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: org.apache.maven.plugin.MojoExecutionException: Fatal error compiling
at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute (AbstractCompilerMojo.java:796)
at org.apache.maven.plugin.compiler.CompilerMojo.execute (CompilerMojo.java:129)
at org.apache.maven.plugin.DefaultBuildpluginManager.executeMojo (DefaultBuildpluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:566)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: org.codehaus.plexus.compiler.CompilerException
at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess (JavaxToolsCompiler.java:191)
at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile (JavacCompiler.java:169)
at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute (AbstractCompilerMojo.java:785)
at org.apache.maven.plugin.compiler.CompilerMojo.execute (CompilerMojo.java:129)
at org.apache.maven.plugin.DefaultBuildpluginManager.executeMojo (DefaultBuildpluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:566)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: java.lang.NullPointerException
at com.sun.tools.javac.main.JavaCompiler.readSourceFile (JavaCompiler.java:841)
at com.sun.tools.javac.processing.JavacProcessingEnvironment$ImplicitCompleter.complete (JavacProcessingEnvironment.java:1521)
at com.sun.tools.javac.code.Symbol.complete (Symbol.java:642)
at com.sun.tools.javac.code.Symbol$ClassSymbol.complete (Symbol.java:1326)
at com.sun.tools.javac.code.Type$Classtype.complete (Type.java:1140)
at com.sun.tools.javac.code.Type$Classtype.getTypeArguments (Type.java:1066)
at com.sun.tools.javac.code.Printer.visitClasstype (Printer.java:237)
at com.sun.tools.javac.code.Printer.visitClasstype (Printer.java:52)
at com.sun.tools.javac.code.Type$Classtype.accept (Type.java:993)
at com.sun.tools.javac.code.Printer.visit (Printer.java:136)
at com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArgument (AbstractDiagnosticFormatter.java:199)
at com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArguments (AbstractDiagnosticFormatter.java:167)
at com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage (BasicDiagnosticFormatter.java:111)
at com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage (BasicDiagnosticFormatter.java:67)
at com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArgument (AbstractDiagnosticFormatter.java:185)
at com.sun.tools.javac.util.AbstractDiagnosticFormatter.formatArguments (AbstractDiagnosticFormatter.java:167)
at com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage (BasicDiagnosticFormatter.java:111)
at com.sun.tools.javac.util.BasicDiagnosticFormatter.formatMessage (BasicDiagnosticFormatter.java:67)
at com.sun.tools.javac.util.JCDiagnostic.getMessage (JCDiagnostic.java:788)
at com.sun.tools.javac.api.ClientCodeWrapper$DiagnosticSourceUnwrapper.getMessage (ClientCodeWrapper.java:799)
at org.codehaus.plexus.compiler.javac.JavaxToolsCompiler.compileInProcess (JavaxToolsCompiler.java:149)
at org.codehaus.plexus.compiler.javac.JavacCompiler.performCompile (JavacCompiler.java:169)
at org.apache.maven.plugin.compiler.AbstractCompilerMojo.execute (AbstractCompilerMojo.java:785)
at org.apache.maven.plugin.compiler.CompilerMojo.execute (CompilerMojo.java:129)
at org.apache.maven.plugin.DefaultBuildpluginManager.executeMojo (DefaultBuildpluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:210)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:156)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:148)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:957)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:289)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:193)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at jdk.internal.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:566)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)`enter code here`
[ERROR]
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more @R_923_4045@ion about the errors and possible solutions,please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
解决方法
sudo update-java-alternatives --list
按名称和目录列出计算机上的所有Java安装，然后 运行
sudo update-java-alternatives --set [JDK / JRE名称，例如java-8-oracle]
选择要使用的JRE / JDK。
如果要为每个Java任务使用不同的JDK / JRE，则可以运行update-alternatives一次配置一个Java可执行文件；您可以运行
sudo update-alternatives --config java [Tab]
查看可以配置的Java命令（java，javac，javah，javaws等）。然后
sudo update-alternatives --config [javac | java | javadoc | etc。
会将Java任务/命令与特定的JDK / JRE相关联。