Java Serialization Example

This code illustrates marking a class as Serializable so it can be written to and read from a file easily. This is also useful if transmitting data via RMI.

PhoneEntry.java: phone book entry: a simple name/number pair
PhoneBook.java: a collection of phone entries
Note that both PhoneEntry.java and PhoneBook.java are marked as Serializable; no other work was done to these two classes to make them work with serialization.
Phones.java: the main. This loads the phone book (if phone-book.dat exists in the current directory), and either adds entries (re-writing phone-book.dat) or looks them up. Note especially the functions Phones.save() and Phones.load(); these illustrate reading and writing a serializable object.

Build the solution by typing

        javac Phones.java

Run the solution by typing

        java -ea Phones add zoe 555-9876

or the like. The -ea option enables assertion checking, which is helpful during development.

For example (where % marks lines entered by the user):

        ls phone-book.dat
        /bin/ls: phone-book.dat: No such file or directory
        % java -ea Phones add zoe 555-9876
        % java -ea Phones get zoe
        Phone # for zoe: 555-9876
        % java -ea Phones get rich
        No phone entry for rich
        % java -ea Phones add zoe 555-6789
        % java -ea Phones get zoe
        Phone # for zoe: 555-6789