The Java, mostly used web application development software on the earth, has became very popular because of it's basic feature platform independence. In contact with this, Sun microsystems founder Jame Gausling and team have introduced lot of excitement features like JDBC (Java Database Connectivity), Swings (A window based application development tool), Threads (To make Java program to do more at a single point of time using a thread which is part of process), Servlets (A server side component which makes Java to support web), JSPs (A different kind of same Servlet technology).
Since Java is a open source product, many tools like Apache, Struts, Springs, Hibernate have been developed on the top of Java standard editions which will make programmers job very simple.
You can read my other post about Java evolution and it's features