class LandAnimal 
{
//some code here

}
class WaterAnimal extends LandAnimal
{
//soma code here
}
class Animal extends landAnimal
{
// here we can access properties  both class
}

class WaterAnimal
{
// code 
}
class LandAnimal extends WaterAnimal
{
  //This class has WaterAnimal properties
}
class Animal extends LandAnimal
{
//This class has both LandAnimal and WaterAnimal properties
}

interface LandAnimals {

   class LandAnimal {
     
         // define the Land Animal prperties
   }
}

interface WaterAnimals{

   class WaterAnimal{
     
         // define the Water Animal prperties
   }
}

Now define the "Animal" class by implementing the two 
interfaces(WaterAnimals and LandAnimals ).

Note1 : Java supports defining the class inside an 
interface.

Note 2 : In the previous answer somebody has defined two 
seperate classes for WaterAnimal and Land animal
and his LandAnimal extends WaterAnimal then LandAnmal 
becomes the Water animal this is poor object orientation.