Shopping cart problem.

Question

I have the following method in the ShoppingCart.class.
When an object of MusicRecording passed into this method, it is intended to return how many objects of the passed MusicRecording object there are in the shoppingCart ArrayList. But this method didn't work, it always returns 0 even when I was sure that the object I passed in should exist in the shoppingCart ArrayList.
Please help me. Many thanks to you all.
ArrayList shoppingCart;
public int getQuantity(MusicRecording m) throws RemoteException{
int quantity=0;
for(int i=0;i<shoppingCart.size();i++){
     if(  (  shoppingCart.get(i) ).equals(m)){
          quantity+=1;
.....................

Answer 1

public int getQuantity(MusicRecording m) throws
RemoteException{
int quantity=0;
for(int i=0;i<shoppingCart.size();i++){
     if(  ( (MusicRecording) shoppingCart.get(i) )==m){ //you're doing exactly the same the default behavior of equals() method does.
          quantity+=1;
return quantity;
}You should override both hashCode() and equals() in the MusicRecording class. Provide the logic that you consider will define two equal MusicRecording's