Java developers absolutely must learn Maven. Maven is the most popular and pervasive build tool in the Java world. Even if you don't use Maven directly, alternatives such as Gradle, Jenkins or Ivy ...
Every programming language comes with a learning curve, but Java shares many similarities with C, C++ and JavaScript. Anyone with experience in any of those languages will pick up Java syntax quickly.
Three years ago, I wrote an article for JavaWorld called “Java Scripting Languages: Which Is Right for You?” When I collected the interpreters to compare, I tried to choose ones that seemed a good fit ...