Help with cast, equals and clone

Hi

Can you tell what a cast of object does?
If we you do for example (int)3.45, it gives the integer part that is 3, but if we do a cast to a object, what it returns?
I have a fraction class and i have to put a clone() and a equals() method, but why and for what i need this methods?
Can you give concret examples?

Thanks

Although I haven't tried it, I believe a cast of "3.45" to an Object will not compile. However, if you cast it to an Integer, it might. Autoboxing obfuscates code IMHO, so I don't use it, which means I'm not that familiar with the details of the rules.