I encountered a problem, when I was in the process of compiling solr6.0 source error, I have installed the ant and ivy, and then solr6 source code catalog Executive eclipse ant eclipse would like to generate a project error as follows " Buildfile: D: \ solr-6.0.0-src \ solr-6.0.0 \ build.xml
BUILD FAILED D: \ solr-6.0.0-src \ solr-6.0.0 \ build.xml: 21: The following error occurred while executing this lin D: \ solr-6.0.0-src \ solr-6.0.0 \ lucene \ common-build.xml: 570: java.lang.NullPointerException at java.util.Arrays.stream (Arrays.java:5004) at java.util.stream.Stream.of (Stream.java:1000) at java.util.stream.ReferencePipeline $ 7 $ 1.accept (ReferencePipeline.java:267) at java.util.stream.ReferencePipeline $ 3 $ 1.accept (ReferencePipeline.java:193) at java.util.Spliterators $ ArraySpliterator.forEachRemaining (Spliterators.java:948) " The same is true for my other ant commands, 570 lines are "<pathconvert property =" dist.jar.dir.suffix ">" This variable is defined earlier as: "<property name =" dist.jar.dir.prefix "value =" $ {lucene.tgz.unpack.dir} /lucene.tgz.unpacked "/> <property name = "lucene.tgz.unpack.dir" location = "$ {common.build.dir} / lucene" /> " lucene.tgz.unpacked This directory does not exist in the system, what do I do wrong?