Main method Signature

[anand phulwani]

HI friends,
can main method method have a parameter other than String[]?

I tried the follwing code...

 
public class test21
{
public static void main(Object a[])
{
System.out.println("HI");
}
} 

it gave to following error:

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

and when i modified the code to be...

 
public class test21
{
public static void main(Object<String> a[])
{
System.out.println("hI");
}
} 

now this code is of generics...and the parameter of main only accepts String. but this gave the following error

 
test21.java:3: type java.lang.Object does not take parameters
        public static void main(Object<String> a[])
                                      ^ 

Can anyone explain me about this?

Thanx

[Barry Gaunt]

Here is the API for class Object. You will see that Object is not a parameterized type, so Object<String> is meaningless.

The main method must have a signature of main(String[] <identifier> ) , and must have modifiers public and static, and a return type of void. It can have additional modifiers and a throws clause.

It seems that you can also use an argument list of String... <identifier>, but that is just "syntatical sugar" for String[] <identifier>.
[ September 11, 2005: Message edited by: Barry Gaunt ]

[Sandeep Chhabra]

Hi,
Instead of posting a new topic I am using the same topic again regarding the main method.
just a small question:

in the statement

public static void main(String[]a)
{
System.out.println(a);//1
}

i want to know whether any object is created? if an object is created is it a String object? and if no object is created then how is the line commented as 1 printing the value [Ljava.lang.String;@10b62c9, it should print null;

Thanx
Sandy

[fred rosenberger]

when you run it, are you passing it any arguments?

My guess is that you are not. so, (and again, this is a guess), an ARRAY object is created, that happens to hold nothing. you then tell it to print the array, which calls the default toString method every object inherits from the Object class, thus giving you that output.

[anand phulwani]

Dear Mr Sandeep,

Here is a simple explaination for it

1)Yes,an object is created.
2)Its an Array Of String Object
which is created ,in the same way as
String b[]=new String[0];
so its printing the class and its hashcode
3)And in Array it prints null only when
we access an Array Element

String b[]=new String[1];
System.out.println(b[0]);//this will print null

heres a code for your help

class Test
{
public static void main(String a[])
{
System.out.println(a);
String b[]=new String[0];
System.out.println(b);
}
}

this results into
[Ljava.lang.String;@10b62c9
[Ljava.lang.String;@82ba41


apart from this Mr Sandeep,
One Small Doubt of mine,i would like to ask that
4)As this is an Member Variable ,it does implicitly initialize a default value, so should it print null if no object is created???,as far as i have learned it is that Member Variables are needed to initialize explicitly otherwise it gives a Compiler Error, that the variable might not have been initialized.

Please Correct Me If I am Wrong.