Question

I have two classes

public class PrepaidPackage {

    private String name;
    private String serviceClassID;
    private boolean isTranferable;

    public boolean isTranferable() {
        return isTranferable;
    }
    public void setTranferable(boolean isTranferable) {
        this.isTranferable = isTranferable;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getServiceClassID() {
        return serviceClassID;
    }
    public void setServiceClassID(String serviceClassID) {
        this.serviceClassID = serviceClassID;
    }
}

other class is

public class PostpaidPackage {
    private String name;
    private boolean isTranferable;
    public boolean isTranferable() {
        return isTranferable;
    }
    public void setTranferable(boolean isTranferable) {
        this.isTranferable = isTranferable;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

I want to create a factory class which on base of package type create relevant class. But if you look at above clasess they dont have same type of methods and variables. So please guide how create interface or abstract class for above class?

Now factory will return class name Package. Would i able to call methods which are not present in other class.

Updates

Please suggest if i break my package into two classes like

public abstract class MyPackage {
    public abstract PackageSpec getSpec();
    public abstract PackagePrepaidDetails getDetail();
}

Now common attributes will be in PackageSpec and prepaid stuff in packageDetails.

Its kind of abstract factory pattern.

public class PrepaidPackage extends MyPackage{
    PackageSpec spec;
    public Spec getSpec() {
      spec = new PackageSpec();
      spec.setTranferable(true)
      spec.setName("abc");
      return spec;
    }
    public PackagePrepaidDetails getDetails() {
      details = new PackagePrepaidDetails ();
      details.setServiceClassID(123)
      return details;
    }
}

public class PostpaidPackage extends MyPackage{
    PackageSpec spec;
    public Spec getSpec() {
        spec = new PackageSpec();
        spec.setTranferable(true)
        spec.setName("abc");
        return spec;
    }
}

Answer 1

I recomment you to have an interface if you don’t have already. You do not neccessarily need it, but it is a good practice if they are so similar:

public interface Package {
    public boolean isTranferable();
    public void setTranferable(boolean isTranferable);
    public String getName();
    public void setName(String name);
}

Then in your calling code, you have a Package from your factory and:

Package p = myFactory.nextPackage();    // or something
if (p instanceof PrepaidPackage) {
    PrepaidPackage prepaid = (PrefpaidPackage)p;
    // and do the thing you want
} else if (p instanceof PostpaidPackage) {
    PostpaidPackage postpaid = (PostpaidPackage)p;
    // amd do the other things
}

Thing you are recommended to llok into is the instanceof operator and type casting.