Today 25 years ago Java made its first public appearance. Back then, Java promised to be a general-purpose programming language that you “write once, run anywhere“. It came with a new and unique way to compile Java source code down to bytecode, an intermediate representation that could be understood, compiled at runtime and run by the Java Virtual Machine (JVM). It was the combination of Java bytecode and the JVM that made it possible for Java to keep that “write once, run anywhere” promise. The Java Virtual Machine was for Java programs exactly what the name suggests, a (virtual) machine. Regardless of which computer you had, which OS you were running, if you had a JVM installed, you could run your compiled Java program on it without the need for porting or recompiling the program first.
Since then Java has come a long way. In some respect, one could argue that Java powers the modern world. Both, TIOBE and Redmonk recon Java to be one of the top programming languages out there today. If you don’t trust analysts, it’s still hard to deny the importance of Java. Some very popular software has been implemented in Java, such as Hadoop, Cassandra, Kafka, Elasticsearch, Jenkins, Jetty, Maven, Liquibase, Spark, and Tomcat. Entire standards and frameworks have emerged thanks to Java and its wider ecosystem: JAX-RS, JMS, Jarkata EE, JDBC, Spring, Log4j, Hibernate, JOOQ. And even other languages have been created that run on top of the Java Virtual Machine, e.g. Scala, Groovy, Kotlin, Jython, JRuby, and Clojure.
It is fair to say that: “Java, you rock! Happy birthday!”