Classes and Objects - Beginning Java 8 Fundamentals - page 232

myCar 8192 9216

model Unknown

year 2000

9216

price 0.0

10240

xyCar 9216

Figure 6-17. Memory state showing myCar and xyCar referencing the same Car object in memory

At this time, you can use reference variables myCar or xyCar to access the Car object in memory. The following
snippet of code will access the same object in memory:

myCar.model = "Civic LX"; /* Use myCar to change model */
myCar.year = 1999; /* Use myCar to change year */
xyCar.price = 16000.00; /* Use xyCar to change the price */

After executing the above three statements, model , year , and price will be changed for the Car object and the
memory state will look as shown in Figure 6-18 .

8192

myCar 9216

model Civic LX

year 1999

9216

price 16000.0

xyCar 10240 9216

Figure 6-18. Memory state showing myCar and xyCar referencing the same Car object in memory after myCar and
xyCar have been used to change the state of the Car object

At this point, two reference variables myCar and xyCar and one Car object exist in memory. Both reference
variables are referencing the same Car object. Let's execute the following statement and label it as #5:

myCar = new Car(); /* #5 */

The above statement will create a new Car object in memory with initial values for its instance variables and
assign the reference of the new Car object to the myCar reference variable. The xyCar reference variable still references
the Car object it was referencing before. Suppose the new Car object has been allocated at memory address 5120 . The
memory state for two reference variables myCar and xyCar and two Car objects is shown in Figure 6-19 .