This week's book giveaway is in the OCMJEA forum. We're giving away four copies of OCM Java EE 6 Enterprise Architect Exam Guide and have Paul Allen & Joseph Bambara on-line! See this thread for details.
I'll try to explain by way of example and diagram: Object obj = new Object(); With the above statement, two things are created: 1) a variable that can refer to an Object (obj) 2) a new instance of the Object class.
Your code gains access to the object via the reference 'obj'. When using it to invoke methods and access data members, you can think of the reference obj as if it were the object itself. However, when doing assignments and passing obj as a parameter to other methods, you have to remember that it is just a reference. For example, if you wrote Object obj = new Object(); Object x = obj;
You now have two references pointing to the same Object. The assignment does not create a new object but merely copies the reference obj to x, in effect, making both x and obj refer to the same Object. The same principle applies when passing obj as a parameter to a method. HTH, Junilu