Java: Variables, References and Objects

Adapted with permission from Arnold Rosenbloom, University of Toronto

*added by MisterV

Variable is a named loaction in main memory.

Primitive Variable

    • A primitve variable will hold the value of a primitive data type.
    • ie. :byte, short, int, long, float, double, char, boolean.

Referenced Variable

    • A Reference holds the address of an instance of an class (a.k.a. an object)
    • A reference is NOT the instance
    • The VALUE of a reference is the address it holds
    • Speed Dial analogy (no Inheritence)

Using Objects

Booloon b1=new Booloon(); does the following :

    1. Create a new instance of Balloon
    2. Call the initialization code for a new Balloon (constructor)
    3. Create a new reference to Balloon called b1
    4. Assign the address of the newly created/initialized balloon to b1

The following are equivalant statments:

Booloon b1=new Booloon();

Booloon b1;

b1=new Booloon();