I have created a class to hold currency types. 
Class is called Currency. Its contents are - 

```
public class Currency{
            public enum CurrencyType {PENNY(1), NICKLE(5), DIME(10), QUARTER(25)};
}

```

In Eclipse, PENNY, NICKLE etc are highlighted in red and error message reads - 

```
The constructor Currency.CurrencyType(int) is undefined

```

Why this error?