在开发机器上典型地安装了cassandra之后，我启动了 nodetool 我得到了以下结果：

error: null
-- StackTrace --
java.lang.NullPointerException
    at org.apache.cassandra.config.DatabaseDescriptor.getDiskFailurePolicy(DatabaseDescriptor.java:1892)
    at org.apache.cassandra.utils.JVMStabilityInspector.inspectThrowable(JVMStabilityInspector.java:82)
    at org.apache.cassandra.io.util.FileUtils.<clinit>(FileUtils.java:79)
    at org.apache.cassandra.utils.FBUtilities.getToolsOutputDirectory(FBUtilities.java:860)
    at org.apache.cassandra.tools.NodeTool.printHistory(NodeTool.java:200)
    at org.apache.cassandra.tools.NodeTool.main(NodeTool.java:168)

我找了一个类似的问题，但是cassandra对java11的支持是非常新的，我不能安装java8，这是解决这个问题的唯一解决方案。
ubuntu版本

No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 18.04.2 LTS
Release:    18.04
Codename:   bionic

java版本

java 11.0.2 2019-01-15 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.2+9-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.2+9-LTS, mixed mode)

Cassandra状态

● cassandra.service - LSB: distributed storage system for structured data
   Loaded: loaded (/etc/init.d/cassandra; generated)
   Active: active (exited) since Wed 2019-05-08 12:30:58 CEST; 15min ago
     Docs: man:systemd-sysv-generator(8)
  Process: 2350 ExecStart=/etc/init.d/cassandra start (code=exited, status=0/SUCCESS)

提前感谢您的解决方案和建议