Java has an Object class in the java.lang package.
All Java classes extend the Object class directly or indirectly.
Object class is the superclass of all classes.
Object class is at the root of class hierarchy.
For the obj variable whose type is Object
You can assign a reference of any object in Java to obj.
assign the null reference
obj = null;
assign a reference of an object of the Object class
obj = new Object();
Can assign a reference of an object of the Account class
Account act = new Account(); obj = act;
The following code tries to assign the same reference back to a reference variable of the Account type.
Object obj2 = new Account(); Account act = (Account)obj2; // Must use a cast