Is null a Java keyword?

Question

Is null is a keyword in Java?

probably because it would've taken less time to google the answer than to ask it. The second google result has the answer in the summary, you wouldn't even have to click the link. — DevinB, Feb 06 '09 at 13:16
No it is literal in Java.You can what null is [here][1] [1]: http://stackoverflow.com/questions/2707322/what-is-null-in-java/7258515#7258515 — Sanjay Jain, Aug 31 '11 at 14:35

score 47 · Answer 1 · edited Sep 18 '14 at 13:36

47

Not according to the Java Language Specification list of keywords. On the other hand, this doesn't compile:

int null = 10;

The rules for identifiers specify that:

An identifier is an unlimited-length sequence of Java letters and Java digits, the first of which must be a Java letter. An identifier cannot have the same spelling (Unicode character sequence) as a keyword (§3.9), boolean literal (§3.10.3), or the null literal (§3.10.7).

I'm not sure what the benefit of making it not-a-keyword is, to be honest.

edited Sep 18 '14 at 13:36

Vy Do

46,709
59
215
313

answered Feb 06 '09 at 09:12

Jon Skeet

1,421,763
867
9,128
9,194

Lol, this answer implies that there are implementations of Java that accept null as a keyword. – Toon Krijthe Feb 06 '09 at 09:12
1

Gamecat, the way i read it, it says clearly the spec does _not_ consider null a keyword. – tehvan Feb 06 '09 at 09:17

score 11 · Answer 2 · edited Jan 22 '19 at 02:12

11

Not a keyword - the null literal.

an identifier (oops, no it isn't)

edited Jan 22 '19 at 02:12

Pang

9,564
146
81
122

answered Feb 06 '09 at 09:13

Marc Gravell

1,026,079
266
2,566
2,900

1

It's not an identifier either, according to http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#40625 – Jon Skeet Feb 06 '09 at 09:15

score 9 · Answer 3 · edited Jan 22 '19 at 02:06

9

null is a literal similar to true and false in Java. These are not keywords because these are the values of something. As null is the value of a reference variable, true is the value of a boolean variable.

edited Jan 22 '19 at 02:06

Pang

9,564
146
81
122

answered Nov 15 '12 at 14:42

saurabh kimothi

91
1
1

score 7 · Answer 4 · answered Feb 07 '09 at 01:38

null is a literal, in the same sense that false, 10, and '\n' are literals. It's not a "keyword", technically, but it is a character string that is treated specially by the compiler if the compiler encounters it in a java source file.

So, no, you cannot name a variable "null". The lexical analyzer will decide that it is not an identifier.

score 6 · Accepted Answer · edited Feb 06 '09 at 09:13

6

No.It is not a keyword.

edited Feb 06 '09 at 09:13

Toon Krijthe

52,876
38
145
202

answered Feb 06 '09 at 09:10

Warrior

39,156
44
139
214

score 3 · Answer 6 · edited Jan 22 '19 at 02:08

3

No. See this for complete list: Java Language Keywords

edited Jan 22 '19 at 02:08

Pang

9,564
146
81
122

answered Feb 06 '09 at 09:14

Nrj

6,723
7
46
58

score 1 · Answer 7 · answered Feb 06 '09 at 21:28

1

true and false are also literals. Java trivia: const and goto are keywords.

answered Feb 06 '09 at 21:28

Peter Lawrey

525,659
79
751
1,130

score 0 · Answer 8 · edited Jan 22 '19 at 02:05

0

No. null is not a keyword in Java.

edited Jan 22 '19 at 02:05

Pang

9,564
146
81
122

answered Dec 11 '13 at 15:29

Pankaj Goyal

950
9
15

score 0 · Answer 9 · edited Jan 22 '19 at 02:04

0

It represents a special value but it's not a keyword in Java, and it doesn't mean that we can use it as an identifier. It's restricted to be used as an identifier and that is obvious because we cannot have a special value as an identifier because the compiler will treat that word (null) as special value, not as identifier.

edited Jan 22 '19 at 02:04

Pang

9,564
146
81
122

answered Oct 22 '17 at 07:28

NAGHMAAN MOHASEEN

45
1
5

Is null a Java keyword?

9 Answers9

Linked