Java can't find method main

Question

Im having trouble with a simple hello world program lol! Im hoping someone can shed some light on this.

So the error im receiving is the following:

$ javac Hello.java
$ java Hello
Exception in thread "main" java.lang.NoSuchMethodError: main

So by the error, I can see that it's obviously missing main, but it's there:

class Hello
{
  public static void main(String argv)
  {
    System.out.println("hello world");
  }
}

I'm on Mac OS/X if it's any help.

String[] argv and not String argv – Sid Aug 03 '12 at 15:31 — Sid, Aug 03 '12 at 15:31

score 10 · Accepted Answer · edited Feb 02 '13 at 00:19

10

Problem is that your method does not take String array as a argument. Use following signature instead:

public static void main(String[] argv)

or

public static void main(String argv[])

Other valid option is:

public static void main(String ... argv)

In Java Language Specification this is told as follows:

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.

edited Feb 02 '13 at 00:19

Pshemo

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answered Jul 30 '12 at 11:20

Mikko Maunu

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You do not have to give it any actual arguments when starting JVM. In such a case main method will receive empty array. – Mikko Maunu Jul 30 '12 at 11:34
Just a side question; Im still receiving the error by removing the args part to just this: `public static void main()` – Menztrual Jul 31 '12 at 00:54
1

That's how it is, main simply needs to have array as an argument. But you do not have to give arguments when you execute it with 'java Hello'. – Mikko Maunu Jul 31 '12 at 04:40

Pshemo · Answer 2 · 2012-07-30T11:34:19.823

4

You forgot about [] in String[] argv or ... in String... argv. This array is used to store arguments used in command creating JVM for your class like

java Hello argument0 argument1 argument2`

and so on.

edited Jul 30 '12 at 11:34

answered Jul 30 '12 at 11:20

Pshemo

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score 4 · Answer 3 · edited May 23 '17 at 12:21

4

Main method has signature that accepts String[] and you wrote String which is wrong,

Make it

public static void main(String[] argv)

or varargs

public static void main(String... argv)

edited May 23 '17 at 12:21

Community

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answered Jul 30 '12 at 11:20

jmj

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score 4 · Answer 4 · answered Jul 30 '12 at 11:23

4

You forgot to put the array syntax, You can even use varargs as per JAVA 1.5

public static void main(String... argv)

answered Jul 30 '12 at 11:23

code-jaff

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Harmeet Singh · Answer 5 · 2012-07-30T11:35:09.743

2

problem is with main signature, which should be

public static void main(String[] argv)

or could be

public static void main(String ... argv) // known as varargs

instead of public static void main(String argv) which is in your case

have a look at this

for varargs look

edited Jul 30 '12 at 11:35

answered Jul 30 '12 at 11:23

Harmeet Singh

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score 2 · Answer 6 · answered Jul 30 '12 at 12:08

2

public static void main(String[] args)
public static void main(String... args)
public static void main(String args[])

Java programs start executing at the main method, which has the above method prototype

answered Jul 30 '12 at 12:08

swapy

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score 1 · Answer 7 · answered Jul 30 '12 at 11:35

1

Your main method signature is wrong String instead of String []

use

public static void main(String[] argv)

or

public static void main(String... argv)

read here

answered Jul 30 '12 at 11:35

subodh

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Java can't find method main

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