Difference between identifier and keyword

[jose chiramal]

Whats the difference between identifier and keyword.

I read this "You can use assert as a keyword or as an identifier but not both" What does this mean ?

[Swati Save]

Keywords are reserved words like(static,public......) which has a special meaning for compilers.

Identifier can be name of any variable or any name used to identify an object or entity .hence keywords cannot be used as an identifier

[Rob Spoor]

There are a few exceptions, mostly caused by changes during a major Java version upgrade.
- Java 1.4 introduced assertions. "assert" became a keyword. You can turn this off by using the compiler flags (-source 1.3) to use Java 1.3 source compatibility, thereby using the keyword "assert" as an identifier
- Java 5.0 introduced enumerations. "enum" became a keyword. See the above; -source 1.4 allows you to use enum as an identifier.

Both will still show a warning but it will no longer be an error.