— Scott McNealy, Sun Microsystems Chairman, President and ceo

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chapter 14
Objects on the heap have state—the 
value of the object’s instance 
variables. These values make one 
instance of a class different from 
another instance of the same class.
What really happens to an object 
when it’s serialized?
Foo myFoo = new Foo();
myFoo.setWidth(37);
myFoo.setHeight(70);
FileOutputStream fs = new FileOutputStream(“foo.ser”);
ObjectOutputStream os = new ObjectOutputStream(fs);
os.writeObject(myFoo);
1
Object on the heap
2
Object serialized
serialized 
objects
00100101
width
01000110
height
00100101
01000110
Serialized objects save the values 
of the instance variables, so that 
an identical instance (object) can be 
brought back to life on the heap.
The instance variable values 
for width and height are 
saved to the file “foo.ser”, 
along with a little more info 
the JVM needs to restore 
the object (like what its 
class type is).
foo.ser
Object with two primitive 
instance variables.
The values are sucked 
out and pumped into 
the stream.
Make a FileOutputStream that connects 
to the file “foo.ser”, then chain an 
ObjectOutputStream to it, and tell the 
ObjectOutputStream to write the object.

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