RandomAccessFile Quick Start

1. RandomAccessFile Quick Start Albert Guo [email protected] 1

2. Agenda RandomAccessFile overview Implement CRUD functions by RandomAccessFile U se case diagram S equence diagram C lass diagram classes 2

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 solution Instant access Insert record without destroying other data Update/delete items without changing other data 3

4. What is RandomAccessFile ? imposes no structure on files Programmer must create random-access files Simplest way: fixed-length records Calculate position in file from record size and key 4

5. Use Case Diagram 5

6. Class Diagram 6

7. DVD.java B e made up of a couple of setter and getter methods D efined length for each column 7 A DVD record

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9. DVDClient.java Play the role of client to do CRUD C (Create): addDVD () R (Read): findAll () and findByCriteria () U (Update): modifyDVD () D (Delete): deleteDVD 9

10. DvdFileAccess.java A ll random access file-related codes are in this class 10

11. findAll () 11

12. 12 R etrieve DVD data based on the cursor

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15. findByCriteria () 15

16. findByCriteria ( ) – cont. 16

17. persistDvd () 17

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20. modifyDVD () 20

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23. deleteDVD () 23

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