Java is the language, the JRE is the runtime environment, and the JDK are the development tools? The JLS is the spec that says that the JRE must do x,y,z, and therefore makes Java what it is? Are these views correct, and if not can someone enlighten me?
Are there any things we think are Java but are not? I think I heard that about Android -- is it true?
To some extent this is a problem of the ambiguity of natural language; some of these things can mean different things at different times.
"Java" can refer to the Java language, as in "I wrote this amazing FooWidget in Java." It can also be shorthand for the Java platform including the language, runtime, tools, etc., as in "You'll need Java to use this web application."
JRE stands for Java Runtime Environment and is the bundled set of APIs included with the Java Virtual Machine. The JDK, or Java Development Kit, is the set of developer tools including the Java compiler, debugger, javadoc compiler, etc. Confusingly, it also includes a JRE (as seen in Eclipse, for example, where the JDK can be specified as the runtime for a project).
The Java Language Specification (JLS) is, um, the spec for the Java Language. Put another way, it describes the technical details of how the language is implemented.
Android is a platform in which the code is written in Java, but compiled to run on the Dalvik virtual machine rather than the JVM. In that sense, it isn't actually Java, but from the perspective of the developer the difference is mostly library use; the syntax is the same.
Similar questions: