Identifier
It is used to identify name, class name, method, variables, object name, interfaces, etc.
class A{
public static void main(String args[])
{
int x=12;
}
}Rules
In the above example A, main, String, args and x are identifier.
- Identifier include a to z, A to Z, 0-9, $
- total_number (valid)
- total# (invalid)
- Identifier can’t stop with digits
- total123 (valid)
- 123total (invalid)
- Uppercase and lowercase are differ meaning
- Maximum characters are allowed there is no length limit
- Reserved words are not allowed
- All Java class names and interfaces names can use as identifiers, but it is worst kind of use
Reserved words
- 53 Reserved words are there
- 50 keyword
48 used
2 unused (goto, const)
- Reserved literal( true, false, null)
- Default return type is int
goto create several problems in old languages that is why Java banned go
Instead
const Already final is there
- All reserved words in Java contains only lower case alphabet symbols
- In Java we have only new and there is no delete keyword because distribution of useless object is the responsibility of garbage collection
- strictfp comes in 1.2 version
- assert comes in 1.4 version
- enum comes in 1.5 version
