Compile Error and correct Syntax

Question

Here is my code; apparently I am missing main. Please help

class A {

    A get(){return this;}

}


class B1 extends A{
    B1 get(){return this;}
    void message(){System.out.println("welcome to covariant return type");}

    public static void main(String args[]){
        new B1().get().message();
    }
}

More likely you are not running the program correctly. e.g. are you running java -cp . B1 ? I suggest you try running (and formatting your code) in your IDE. — Peter Lawrey
– Peter Lawrey, Commented Dec 9, 2014 at 19:00
@MichalWilkowski, B1 must be declared public and you are right. Nothing has changed since you have learned java specs :).. — User27854
– User27854, Commented Dec 9, 2014 at 19:23

cno · Accepted Answer · 2014-12-09 19:44:19Z

1

Class A

public class A
{
    public A get()
    {
        return this;
    }
}

Class B1

public class B1 extends A
{
    public B1 get()
    {
        return this;
    }

    public void message()
    {
        System.out.println("welcome to covariant return type");
    }
}

Main method

public static void main(String[] args)
{
     B1 b1 = new B1();
     B1 b2 = b1.get();

     b2.message();
}

If you write it out like this, it's a bit clearer for you and for others to read. The main method should be enclosed in a class, but I separated it out so you can see each component of your code.

edited Dec 9, 2014 at 19:44

answered Dec 9, 2014 at 19:27

cno

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1 Comment

fjf2002 Over a year ago

The main method has to be inside some class.

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