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Reserved words vs. keywords


Joined: Sep 19, 2000
Posts: 6
What is the difference between a Java keyword and a java reserved word?
Gina Pandher

Joined: Sep 21, 2000
Posts: 19
Keywords are special reserved words in java.
There are 48 reserved keywords in the java language. These keywords cannot be used as names for a variable,class or method.
In addition to these 48 reserved keywords java also reserves : true, false and null. These also may not be used for names of variables, classes.
Any book on Java that you refer to will enumerate these reserved keywords.
Hope it is clear.
Marilyn de Queiroz

Joined: Jul 22, 2000
Posts: 9058
Yes, keywords are reserved words. Many books on java list the keywords and the reserved words together. Some books have 49 reserved/keywords. But why are the 3 extra reserved words not keywords? Why are they different?

"Yesterday is history, tomorrow is a mystery, and today is a gift; that's why they call it the present." Eleanor Roosevelt
Steve Fahlbusch

Joined: Sep 18, 2000
Posts: 596

From the language specification

The following character sequences, formed from ASCII letters, are reserved for use as keywords and cannot be used as identifiers (�3.8):
Keyword: one of
abstract default if private this
boolean do implements protected throw
break double import public throws
byte else instanceof return transient
case extends int short try
catch final interface static void
char finally long strictfp volatile
class float native super while
const for new switch
continue goto package synchronized
The keywords const and goto are reserved, even though they are not currently used. This may allow a Java compiler to produce better error messages if these C++ keywords incorrectly appear in programs.
While true and false might appear to be keywords, they are technically Boolean literals (�3.10.3). Similarly, while null might appear to be a keyword, it is technically the null literal (�3.10.7).

> Half of my Java books include true, false and null as
> keywords - half don't

Bhuvana Dhruva

Joined: Sep 11, 2000
Posts: 28
from Thinking in java by Bruce Eckel, we know that null, true and false are java reserved literals, ie they r values

I agree. Here's the link:
subject: Reserved words vs. keywords
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