CODEWITHSUNDEEP
java
Tom
Tom

Reputation: 91

Variable within constructor is returning null?

I am doing a project based around the concepts of inheritance and have created a super constructor which has two variables within itself (String, int), this super constructor is then called within a sub constructor that inherited the super constructors class. I then use two methods to return the properties of those variables within the constructors. The age property is outputting fine but the String property is returning null. Here's the code:

Animal super-class

abstract public class Animal 
{

    int age;
    String name;

Animal(String name, int age)   
{
    this.age = age;
    this.name = name;
} 


Animal()
{
  this("newborn", 0);
}


public String getName() {
        return name;
    }

    public void setName(String newName) {
        name = newName;
    }

}

Wolf sub-class

public class Wolf extends Carnivore
{

    String name;
    int age;

Wolf(String name, int age)   
{  
    this.name = name;
    this.age = age;
}

Wolf()
{
  super();
}

    public String getName() 
    {
        return name;
    }  

    public int getAge()
    {
        return age;
    }

}

Main method class

public class Main {


    public static void main(String[] args) 
    {

    Wolf newWolf = new Wolf();
    System.out.println("Name = " + newWolf.getName());
    System.out.println("Age = " + newWolf.getAge());

}
}

Age is returning as 0 which is correct but System.out.println("Name = " + newWolf.getName()); seems to be returning null instead of "newborn". Any help on resolving this issue is appreciated thanks.

Update - I need the getName() method for another constructor that I haven't included in this example so is there a way to have them both exist?

Upvotes: 2

Views: 356

Answers (1)

Nir Levy
Nir Levy

Reputation: 12953

The issue here is that you are defining your fields in the sub-class, you don't need to as they are inherited from the parent.

Your class has two sets of fields, one from the super (these are the ones set by your constructor, which is calling super() and the other from the child class (these are the ones returned by your getters, which are not initialized. the zero is int's default, not set either).

So simply remove the fields definition from the child class

Upvotes: 2

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