CODEWITHSUNDEEP
javaabstract-classclonesubclasssuperclass
Keval
Keval

Reputation: 1602

Make a new instance of an unknown subclass using superclass object in java

Here I have an abstract class Person and multiple subclasses:

public abstract class Person {

    public String name;

    public Person(String name) {
        this.name = name;
    }
}

public class ComputerScientist extends Person {

    public String job;

    public ComputerScientist(String name, String job) {
        super(name);
        this.job = job;
    }
}

public class SoftwareEngineer extends Person {

    public String job;

    public SoftwareEngineer(String name, String job) {
        super(name);
        this.job = null;
    }
}

This is what I run:

public static void main(String[] args) {
    List<Person> people = new ArrayList<Person>();
    person.add(new ComputerScientist("ben", "job"));
    person.add(new SoftwareEngineer("larry", "job"));
    Random r = new Random();

    Person person = people.get(r.nextInt(people.size() - 1);
}

Person becomes the same as the Person in the list, how do I get it as a person clone. Cloning and new Instance do not work.

I can probably do it using a copy method (requres me to rewrite a great deal of code) but is there any (perhaps more efficient) way to do it without?

Upvotes: 0

Views: 751

Answers (3)

nits.kk
nits.kk

Reputation: 5316

You can create a method to create a new Object of the Person(as per the sub class) and another method to copy the states in the new object. Refer below approach for the basic implementation of the same.

public abstract class Person{
  ...//your states and methods
  protected void copy(Person copiedPerson){
        copiedPerson.name = this.name;
  }

  public abstract Person getCopyPerson();
}

public class SoftwareEngineer extends Person{

     ....//your states and methods
    @override
     protected void copy( Person copiedPerson ){
          super(copiedPerson);
          copiedPerson.job = this.job;
     }

    @override
    public Person getCopyPerson(){
       Person copyPerson = new SoftwareEngineer();
       copy(copyPerson);
       return copyPerson;
    }

}

Now whenever you fetch the object of Person, simply call getCopyPerson() on it to get a copy object.

Upvotes: 1

Emerson Cod
Emerson Cod

Reputation: 2090

I'm not a fan of clone() - see also Clone() vs Copy constructor- which is recommended in java

So, instead use a copy constructor or copy method, that accepts a person and then transfers the relevant information

Upvotes: 1

Birbal Singh
Birbal Singh

Reputation: 1072

Make your class cloneable with implements with Cloneable interface. and at object user .clone() method to clone of person class object

Upvotes: 0

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