Implicit promotion for constructor arguments

[Andreas Sandberg]

Hi Folks,

Can somebody explain why the code below compiles. Why does Main a = new Main(3) call the constructor that takes the float argument. How does JAVA handle implicit promotion for constructor arguments? Thanks!

 
class Main
{
 int i;
    Main()
    {
        i = 3;
        System.out.println(i);
    }
    
    Main(float i)
    {
        this();
    }
 
    public static void main(String[] args)
    {
        Main a = new Main(3); // Compiles but argument is an int, not float.
    }
 
}
  

[Seb Mathe]

That's because an int can be automaticly converted to a float (or to a long, or a double)

[Raghu Shree]

Hi,

int value 3 is converted into float. So Math(3) is executed. For more information about casting refer this link.

http://www.javaranch.com/maha/Resources/CarlsNotes.txt

[A Kumar]

Hi,

You can look at this way


byte->short->int->long->float->double

In fact here you can have char converts into int...apart from short...

char->int..



[ October 20, 2005: Message edited by: A Kumar ]

[ October 20, 2005: Message edited by: A Kumar ]
[ October 20, 2005: Message edited by: A Kumar ]

[Henry Wong]

Try it with code tags...

Henry

  byte->short->int->long->float->double
                ^
                |
               char

[A Kumar]

Hi.

Thanks Henry...Thats what i was trying to convey...

[Thomas Drew]

Andreas
In your constructor Main(float i) you pass the float value for i in but you never assign it to anything. The this() call your constructor with no arguments which is always going to assign the value 3 to i.