Extending object, without calling super constructor

Question

public class Object1
    byte index;
    public Object1(byte i)
        index = i;
public class Object2 extends Object1
    private byte j;
    public Object2() {
        super((byte) 0);
    public void setIndex(byte i)
        j = i;
import java.util.*;
public class Test1
    private ArrayList<Object1> aList;
    public Test1()
        aList = new ArrayList<Object1>();
    public void run()
        for (byte i = 0; i < 10; i++)
            aList.add(new Object1(i));
    public ArrayList<Object1> getResults()
        return aList;
import java.util.*;
public class Test2
    ArrayList<Object1> results;
     * Constructor for objects of class Test2
    public Test2()
        Test1 t1 = new Test1();
        t1.run();
        results = t1.getResults();
    public void run()
        Iterator<Object1> i = results.iterator();
        while (i.hasNext())
            Object2 o2 = (Object2) i.next();
public class Test3
    public static void main(String[] args)
        Test2 t2 = new Test2();
        t2.run();
}There are two things with this code that I'm having problems with.
1. I want to create an object of class Object1 in Test1. That works fine. In Test2 I then want to extract the object from the ArrayList, but since Object2 extends Object1, I want to get an Object2 out from the ArrayList. However with the code above, I get a ClassCastException. If I leave out the cast, I get an incompatible types error.
2. I want Object2 to be an extension of Object1, that is, with more fields and methods. But I have no need to create an object of class Object2, since I know I already have an ArrayList of Object1. So I want to remove the constructor from Object2, seeing as I won't need it. However, if I remove the super part (which, again, is not needed, as I will already have created my needed objects of class Object1 when I get there, and only need to EXTEND my Object1 objects), I get a cannot find symbol, constructor Object1() error.
I'm not sure that I can solve problem 2 without using a super. But I am convinced that I must be able to get the Object1 objects out as Object2 instead. I would just like some help with how to do that.

Answer 1

ThemePark wrote:
But I am convinced that I must be able to get the Object1 objects out as Object2 instead. I would just like some help with how to do that.Maybe you don't understand how inheritance works. Go read a basic tutorial on inheritance. You can use an Object2 as an Object1, but not an Object1 as an Object2. You either have to create Object2 objects in the first place; or have to make a wrapper class that takes an Object1 and passes things to the Object1 object; and use objects of this wrapper class.