Why do people leave unused `String args[]` in Java?

Question

When I see Java programs, many leave the String args[] on even though the program doesn't use them. Why is this? Anything in particular?

http://stackoverflow.com/q/1672083/139010 – Matt Ball May 09 '13 at 00:50 — Matt Ball, May 09 '13 at 00:50

score 10 · Accepted Answer · edited May 09 '13 at 00:49

10

String args[] is part of the method signature for main. If you don't have it you will get the exception below when you try and run the code.

Exception in thread "main" java.lang.NoSuchMethodError: main

edited May 09 '13 at 00:49

Andrew Thompson

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answered May 09 '13 at 00:48

FDinoff

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http://pastebin.com/5KQYZ1VV This runs fine for me, though... – MarJamRob May 09 '13 at 00:50
I get the exception when I use the java compiler for mac (version javac 1.6.0_45). What compiler are you using? – FDinoff May 09 '13 at 00:52
javac 1.7.0_10 on OSX 10.7 – MarJamRob May 09 '13 at 00:54
I don't have that specific compiler on my computer. When I tried it with a javac version 1.7.0_11 on Fedora. I got a `Error: Main method not found in class tut21, please define the main method as: public static void main(String[] args)` So I do not know why you can run it. You shouldn't be able to. – FDinoff May 09 '13 at 00:58
@MarJamRob, either your compiler is broken or you're not running the class file you think you are. JLS7 explicitly states the parameter is required (see KevinB's answer). – paxdiablo May 09 '13 at 01:01

score 7 · Answer 2 · answered May 09 '13 at 00:48

7

If it is for a main(String[]) it is to fulfill the method signature & therefore vital.

answered May 09 '13 at 00:48

Andrew Thompson

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score 3 · Answer 3 · answered May 09 '13 at 00:51

3

Its required by the specification.

The method main must be declared public, static, and void. It must specify a formal parameter (§8.4.1) whose declared type is array of String. Therefore, either of the following declarations is acceptable:

public static void main(String[] args)

public static void main(String... args)

Specification

answered May 09 '13 at 00:51

Kevin Bowersox

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+1 for the JLS7 reference. – paxdiablo May 09 '13 at 01:02

score 2 · Answer 4 · answered May 09 '13 at 00:52

The code within the main may not directly use it, but it is still required. 'String args[]' is where any command line arguments are passed. Even if you pass in 0 arguments, there needs to be a way for that to be verified. It is also the required signature for main by the requirements of the JVM.

Why do people leave unused `String args[]` in Java?

4 Answers4