Abstract classes: Why do they need constructors?

Question

As we cannot instantiate an abstract class. Why does an abstract class need a constructor?.can anyone please help me out..Thnq in advance
OBELISK

Answer 1

import java.util.*;
import static java.lang.System.out;
interface LineItem{
    public int getCost();
abstract class AbstractLineItem implements LineItem{
  protected String name;
  AbstractLineItem(String name){
     this.name = name;
  public String toString(){
    return this.name+" "+getCost();
  public abstract int getCost();
class ProductItem extends AbstractLineItem{
   private int quantity, peritem;
   ProductItem(String name, int quantity, int peritem){
     super(quantity+" "+name);
     this.quantity = quantity;
     this.peritem = peritem;
   public int getCost(){
     return this.quantity*this.peritem;
class FlatFeeItem extends AbstractLineItem{
   private int fee;
   FlatFeeItem(String name, int fee){
     super(name);
     this.fee = fee;
   public int getCost(){
     return this.fee;
public class Test{
  public static void main(String ... args){
    List<LineItem> items = new ArrayList<LineItem>();
    items.add(new ProductItem("Banana",6,1));
    items.add(new FlatFeeItem("Some boring thing or another",35));
    items.add(new ProductItem("Kiwi",3,3));
    for(LineItem item : items)
      out.println(item);
}