This document provides an overview of RandomAccessFile in Java and how it can be used to implement CRUD functions to manipulate data stored in a file. It includes use case diagrams, sequence diagrams, and class diagrams showing classes like DVD, DVDClient, and DvdFileAccess that can be used to create, read, update, and delete DVD records from a random access file by record ID without rewriting the entire file.

1. RandomAccessFile Quick StartAlbert Guojunyuo@gmail.com1

2. AgendaRandomAccessFile overviewImplement CRUD functions by RandomAccessFileUse case diagramSequence diagramClass diagramclasses2

3. What is RandomAccessFile?A random access file behaves like a large array of bytes stored in the file system. There is a kind of cursor, or index into the implied array, called the file pointer; input operations read bytes starting at the file pointer and advance the file pointer past the bytes read.Random-access files are solutionInstant accessInsert record without destroying other dataUpdate/delete items without changing other data3

4. What is RandomAccessFile?imposes no structure on filesProgrammer must create random-access filesSimplest way: fixed-length recordsCalculate position in file from record size and key4

5. Use Case Diagram5

6. Class Diagram6

7. DVD.javaBe made up of a couple of setter and getter methodsDefined length for each column7A DVD record

8. 8

9. DVDClient.javaPlay the role of client to do CRUDC (Create): addDVD()R (Read): findAll() and findByCriteria()U (Update): modifyDVD()D (Delete): deleteDVD9

10. DvdFileAccess.javaAll random access file-related codes are in this class10

11. findAll()11

12. 12Retrieve DVD data based on the cursor

13. 13

14. 14

15. findByCriteria()15

16. findByCriteria() – cont.16

17. persistDvd()17

18. 18

19. 19

20. modifyDVD()20

21. 21

22. 22

23. deleteDVD()23

24. 24