public class MainClass
{

  public static void main(String[] args)
  {

    Object a = new A();
    A b = new B();

    System.out.println(a.equals(b));

  }
}


public class A
{
    public boolean equals (A other)
    {
      System.out.println("a");
      return true;
    }
}

public class B extends A
{

    public boolean equals (Object other)
    {
      System.out.println("b");
      return true;
    }

    public boolean equals (B other)
    {
      System.out.println("c");
      return true;
    }
}

a.equals(b);

b.equals(a);