scala安装及启动Scala报空指针异常的解决方法

1.在官网下载对应的安装包https://www.scala-lang.org/download/

2.安装

选项位置保持默认即可,path环境建议手动添加,在安装中吧path勾掉

3.配置环境变量

SCALA_HOME: 变量值一栏输入：C:\Program Files（x86）\scala 也就是 Scala 的安装目录

path里面添加%SCALA_HOME%\bin

4.安装成功

scala报错 命令窗口(cmd)运行Scala报空指针异常

scala> Exception in thread “main” java.lang.NullPointerException
at java.util.Arrays.sort(Arrays.java:1438)
at scala.tools.nsc.classpath.JFileDirectoryLookup.listChildren(DirectoryClassPath.scala:124)
at scala.tools.nsc.classpath.JFileDirectoryLookup.listChildren$(DirectoryClassPath.scala:108) at scala.tools.nsc.classpath.DirectoryClassPath.listChildren(DirectoryClassPath.scala:297) at scala.tools.nsc.classpath.DirectoryClassPath.listChildren(DirectoryClassPath.scala:297) at scala.tools.nsc.classpath.DirectoryLookup.list(DirectoryClassPath.scala:84) at scala.tools.nsc.classpath.DirectoryLookup.list$(DirectoryClassPath.scala:108)atscala.tools.nsc.classpath.DirectoryClassPath.listChildren(DirectoryClassPath.scala:297)atscala.tools.nsc.classpath.DirectoryClassPath.listChildren(DirectoryClassPath.scala:297)atscala.tools.nsc.classpath.DirectoryLookup.list(DirectoryClassPath.scala:84)atscala.tools.nsc.classpath.DirectoryLookup.list(DirectoryClassPath.scala:80)
at scala.tools.nsc.classpath.DirectoryClassPath.list(DirectoryClassPath.scala:297)
at scala.tools.nsc.classpath.AggregateClassPath.$anonfun$anonfunlist$1(AggregateClassPath.scala:83) at scala.collection.StrictOptimizedIterableOps.map(StrictOptimizedIterableOps.scala:100) at scala.collection.StrictOptimizedIterableOps.map$1(AggregateClassPath.scala:83)atscala.collection.StrictOptimizedIterableOps.map(StrictOptimizedIterableOps.scala:100)atscala.collection.StrictOptimizedIterableOps.map(StrictOptimizedIterableOps.scala:87)
at scala.collection.immutable.Vector.map(Vector.scala:113)
at scala.tools.nsc.classpath.AggregateClassPath.list(AggregateClassPath.scala:81)
at scala.tools.nsc.symtab.SymbolLoaders$PackageLoader.doComplete(SymbolLoaders.scala:278) at scala.tools.nsc.symtab.SymbolLoaders$PackageLoader.doComplete(SymbolLoaders.scala:278)atscala.tools.nsc.symtab.SymbolLoadersSymbolLoader.$anonfun$anonfuncomplete$2(SymbolLoaders.scala:230) at scala.tools.nsc.symtab.SymbolLoaders$2(SymbolLoaders.scala:230)atscala.tools.nsc.symtab.SymbolLoadersSymbolLoader.complete(SymbolLoaders.scala:228)
at scala.reflect.internal.Symbols$Symbol.completeInfo(Symbols.scala:1544) at scala.reflect.internal.Symbols$Symbol.completeInfo(Symbols.scala:1544)atscala.reflect.internal.SymbolsSymbol.info(Symbols.scala:1517)
at scala.reflect.internal.Mirrors$RootsBase.init(Mirrors.scala:255) at scala.tools.nsc.Global.rootMirror$RootsBase.init(Mirrors.scala:255)atscala.tools.nsc.Global.rootMirrorlzycompute(Global.scala:76)
at scala.tools.nsc.Global.rootMirror(Global.scala:74)
at scala.tools.nsc.Global.rootMirror(Global.scala:46)
at scala.reflect.internal.Definitions$DefinitionsClass.ObjectClass$DefinitionsClass.ObjectClasslzycompute(Definitions.scala:286)
at scala.reflect.internal.Definitions$DefinitionsClass.ObjectClass(Definitions.scala:286) at scala.reflect.internal.Definitions$DefinitionsClass.ObjectClass(Definitions.scala:286)atscala.reflect.internal.DefinitionsDefinitionsClass.init(Definitions.scala:1572)
at scala.tools.nsc.Global$Run.(Global.scala:1204)
at scala.tools.nsc.interpreter.IMain.liftedTree1$1(IMain.scala:146) at scala.tools.nsc.interpreter.IMain.global$1(IMain.scala:146)atscala.tools.nsc.interpreter.IMain.globallzycompute(IMain.scala:145)
at scala.tools.nsc.interpreter.IMain.global(IMain.scala:136)
at scala.tools.nsc.interpreter.IMain.withSuppressedSettings(IMain.scala:102)
at scala.tools.nsc.interpreter.shell.ILoop.$anonfun$anonfunrun$2(ILoop.scala:997) at scala.runtime.java8.JFunction0$2(ILoop.scala:997)atscala.runtime.java8.JFunction0mcV$sp.apply(JFunction0$sp.apply(JFunction0mcV$sp.scala:18) at scala.tools.nsc.interpreter.shell.ReplReporterImpl.withoutPrintingResults(Reporter.scala:64) at scala.tools.nsc.interpreter.shell.ILoop.$sp.scala:18)atscala.tools.nsc.interpreter.shell.ReplReporterImpl.withoutPrintingResults(Reporter.scala:64)atscala.tools.nsc.interpreter.shell.ILoop.anonfun$run$1(ILoop.scala:997)
at scala.tools.nsc.interpreter.shell.ILoop.run(ILoop.scala:995)
at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:87)
at scala.tools.nsc.MainGenericRunner.run$1(MainGenericRunner.scala:91) at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:102) at scala.tools.nsc.MainGenericRunner$1(MainGenericRunner.scala:91)atscala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:102)atscala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala:107)
at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

ala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

Scala需要在环境变量中配置classpath(jkd)不配置或配置错就会报出这个错误