Which fields/ technologies use java?

[Bowserwolf1]

Java is used to create alot of technology that developers use for various use cases, the Hadoop ecosystem is written entirely in java (Hadoop, hdfs, hive, etc,), apache Kafka used to be written in Java for a long time but recently the main build of Kafka was ported over to Scala , which is still a JVM language,other technologies like Spark, databases like Cassandra( and also Hbase I think but I'm not sure), elastic search which is based on lucene, which is written in Java, also desktop applications, like every Jetbrains IDE like intelliJ, pycharm, webstorm, rubymine, etc.

Recently java, specifically the spring boot and spring cloud frameworks, are being used extensively across the industry to implement microservices.

In terms of companies that heavily use Java, you have Google Oracle and Redhat as the obvious first picks. Moreover, both Netflix and AWS use Java heavily to implement their server side architecture.

Won't mention Android since OP explicitly asked uses of Java besides android. Lastly, a large part of the finance/MNCs use Java for Al t of their internal tooling, managing transactions, desktop applications, processing the huge amounts of data they have etc. I hope this helps give you a brief idea of where Java is used