Unable to compile java file with gcj 4.1.1: undefined reference to main

Unable to compile java file with gcj 4.1.1: undefined reference to main

[Stephen Torri]

I am having trouble building a java file with gcj. If I attempt to build
it from the obfuscated class file (a.class) I get the error message:

storri@base$ gcj a.class
/usr/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../crt1.o: In function `_start':
init.c:(.text+0x18): undefined reference to `main'
collect2: ld returned 1 exit status

So I though okay I will let gcj reading the straight Java source file. I
get the same error message. Given the source file below is there any
reason why GCJ cannot compile it?

Stephen

----------------------
class Fibonacci {

	public int calculate ( int n )
	{
		int output = 0;

		if ( n > 1 )
		{
			output = calculate ( n - 1 ) + calculate ( n - 2 );
		}
		else
		{
			output = n;
		}

		return output;
	}

	public static void main ( String[] inc )
	{
		if ( inc.length > 0 )
		{
			Fibonacci f_ref = new Fibonacci();

			int n = Integer.parseInt(inc[0]);
			while ( n != -1 )
			{
				System.out.println( "Calculated fibonacci number: " +
f_ref.calculate ( n ) );
				n--;
			}
		}
		return;
	}
}

Re: Unable to compile java file with gcj 4.1.1: undefined reference to main

[Andrew Haley]

Stephen Torri writes:
 > I am having trouble building a java file with gcj. If I attempt to build
 > it from the obfuscated class file (a.class) I get the error message:
 > 
 > storri@base$ gcj a.class
 > /usr/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../crt1.o: In function `_start':
 > init.c:(.text+0x18): undefined reference to `main'
 > collect2: ld returned 1 exit status
 > 
 > So I though okay I will let gcj reading the straight Java source file. I
 > get the same error message. Given the source file below is there any
 > reason why GCJ cannot compile it?

Works for me:

zorro:~ $ gcj Fibonacci.java --main=Fibonacci
zorro:~ $ ./a.out 6
Calculated fibonacci number: 8
Calculated fibonacci number: 5
Calculated fibonacci number: 3
Calculated fibonacci number: 2
Calculated fibonacci number: 1
Calculated fibonacci number: 1
Calculated fibonacci number: 0

Andrew.

Re: Unable to compile java file with gcj 4.1.1: undefined reference to main

[Stephen Torri]

On Tue, 2007-02-27 at 10:03 +0000, Andrew Haley wrote:
> Stephen Torri writes:
>  > I am having trouble building a java file with gcj. If I attempt to build
>  > it from the obfuscated class file (a.class) I get the error message:
>  > 
>  > storri@base$ gcj a.class
>  > /usr/lib/gcc/i686-pc-linux-gnu/4.1.1/../../../crt1.o: In function `_start':
>  > init.c:(.text+0x18): undefined reference to `main'
>  > collect2: ld returned 1 exit status
>  > 
>  > So I though okay I will let gcj reading the straight Java source file. I
>  > get the same error message. Given the source file below is there any
>  > reason why GCJ cannot compile it?
> 
> Works for me:
> 
> zorro:~ $ gcj Fibonacci.java --main=Fibonacci
> zorro:~ $ ./a.out 6
> Calculated fibonacci number: 8
> Calculated fibonacci number: 5
> Calculated fibonacci number: 3
> Calculated fibonacci number: 2
> Calculated fibonacci number: 1
> Calculated fibonacci number: 1
> Calculated fibonacci number: 0

Ah. Thanks for the hint on using --main. I did not think to use that
since I never had to do that for a C/C++ program. Now I am back into to
business.

Stephen