I have Java code that looks something like this:
public class Animal { Animal(String name) { // some code } } And a subclass like this:
public class Dog extends Animal { Dog(String name) { // SAME code as Animal constructor } } The only difference between Dog and the Animal is that Dog has some methods that override the superclass. Their constructors have exactly the same code. How can I avoid this duplicated code? I know that an object can't inherit constructors.
If the constructors are the same you don't need to it in Dog. You have access to the Animal constructor from Dog by calling super(name);.
public class Animal { Animal(String name) { // some code } } And in Dog:
public class Dog { Dog(String name) { super(name); } } It's worth noting that a call to a superclass' constructor must be the first line in your constructor. But after you have called super(name) you can go on and do other Dog-specific code.
For example:
public class Dog { Dog(String name) { // You can't put any code here super(name); // But you can put other code here } } You can delegate to the super constructor:
Dog(String name) { super(name); } See also: http://docs.oracle.com/javase/tutorial/java/IandI/super.html.
Dog object is an Animal object, regardless of whether you call the super constructor. For example, if you have class Dog, class Cat, and class Fish, which all extend class Animal, they can all be put into the same Animal array.