Java is a programming language originally developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995 as a core component of Sun Microsystems’ Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities. Java applications are typically compiled to bytecode (class file) that can run on any Java Virtual Machine (JVM) regardless of computer architecture. Java is a general-purpose, concurrent, class-based, object-oriented language that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers “write once, run anywhere”. Java is currently one of the most popular programming languages in use, and is widely used from application software to web applications. The original and reference implementation Java compilers, virtual machines, and class libraries were developed by Sun from 1995. As of May 2007, in compliance with the specifications of the Java Community Process, Sun relicensed most of its Java technologies under the GNU General Public License. Others have also developed alternative implementations of these Sun technologies, such as the GNU Compiler for Java, GNU Classpath, and Dalvik.
1st thing you should do that download the jdk (java development kit) from here and then download any of the IDE. For java you should know the java documentation (javadoc) and the Java Language Specification (JLS).
There were five primary goals in the creation of the Java language:
1. It should be “simple, object oriented, and familiar”.
2. It should be “robust and secure”.
3. It should have “an architecture-neutral and portable environment”.
4. It should execute with “high performance”.
5. It should be “interpreted, threaded, and dynamic”.
There are several IDE (Integrated development environment) for java like