sbt命令抛出空指针异常。

Question

我是scala和sbt的新手，我想运行sbt命令，但是我得到了一些Null指针异常，不知道原因。

我在系统中安装了scala：

scala -version Scala代码运行程序版本2.11.8 --版权2002-2016年，LAMP/EPFL

另外，如果我试着检查sbt版本，效果很好：

sbt - sbt启动器版本0.13.5

但是当我运行sbt时，我得到了一个例外：

  info] Loading project definition from /home/workspace/myproject
    java.lang.NullPointerException
        at java.util.regex.Matcher.getTextLength(java.base@9-internal/Matcher.java:1747)
        at java.util.regex.Matcher.reset(java.base@9-internal/Matcher.java:402)
        at java.util.regex.Matcher.<init>(java.base@9-internal/Matcher.java:244)
        at java.util.regex.Pattern.matcher(java.base@9-internal/Pattern.java:1108)
        at java.util.regex.Pattern.split(java.base@9-internal/Pattern.java:1221)
        at java.util.regex.Pattern.split(java.base@9-internal/Pattern.java:1288)
        at sbt.IO$.pathSplit(IO.scala:744)
        at sbt.IO$.parseClasspath(IO.scala:859)
        at sbt.compiler.CompilerArguments.extClasspath(CompilerArguments.scala:62)
        at sbt.compiler.MixedAnalyzingCompiler$.withBootclasspath(MixedAnalyzingCompiler.scala:189)
        at sbt.compiler.MixedAnalyzingCompiler$.searchClasspathAndLookup(MixedAnalyzingCompiler.scala:167)
        at sbt.compiler.MixedAnalyzingCompiler$.apply(MixedAnalyzingCompiler.scala:177)
        at sbt.compiler.IC$.incrementalCompile(IncrementalCompiler.scala:138)
        at sbt.Compiler$.compile(Compiler.scala:128)
        at sbt.Compiler$.compile(Compiler.scala:114)
        at sbt.Defaults$.sbt$Defaults$$compileIncrementalTaskImpl(Defaults.scala:814)
        at sbt.Defaults$$anonfun$compileIncrementalTask$1.apply(Defaults.scala:805)
        at sbt.Defaults$$anonfun$compileIncrementalTask$1.apply(Defaults.scala:803)
        at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
        at sbt.$tilde$greater$$anonfun$$u2219$1.apply(TypeFunctions.scala:40)
        at sbt.std.Transform$$anon$4.work(System.scala:63)
        at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:226)
        at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:226)
        at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
        at sbt.Execute.work(Execute.scala:235)
        at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:226)
        at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:226)
        at sbt.ConcurrentRestrictions$$anon$4$$anonfun$1.apply(ConcurrentRestrictions.scala:159)
        at sbt.CompletionService$$anon$2.call(CompletionService.scala:28)
        at java.util.concurrent.FutureTask.run(java.base@9-internal/FutureTask.java:266)
        at java.util.concurrent.Executors$RunnableAdapter.call(java.base@9-internal/Executors.java:514)
        at java.util.concurrent.FutureTask.run(java.base@9-internal/FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(java.base@9-internal/ThreadPoolExecutor.java:1158)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(java.base@9-internal/ThreadPoolExecutor.java:632)
        at java.lang.Thread.run(java.base@9-internal/Thread.java:804)
    [error] (compile:compileIncremental) java.lang.NullPointerException

知道怎么解决这个问题吗？

Answer 1

堆栈跟踪

Loading project definition from /home/workspace/myproject
    java.lang.NullPointerException
        at java.util.regex.Matcher.getTextLength(java.base@9-internal/Matcher.java:1747)
        at java.util.regex.Matcher.reset(java.base@9-internal/Matcher.java:402)
        at java.util.regex.Matcher.<init>(java.base@9-internal/Matcher.java:244)
        at java.util.regex.Pattern.matcher(java.base@9-internal/Pattern.java:1108)
        at java.util.regex.Pattern.split(java.base@9-internal/Pattern.java:1221)
        at java.util.regex.Pattern.split(java.base@9-internal/Pattern.java:1288)

指示您尝试在JDK 9下运行SBT0.13.5，当时不支持该操作。正如第三位评论中所建议的那样，在建议的操作过程中使用JDK 8。

如果您使用的是JDK 9或10，那么使用最新的启动脚本SBT1.1.6或更高版本应该更好。