IB Computing: Java file handling

Files

SL students can even use SQL statements to save, retrieve and edit records in an external (eg Access) database.

This was mentioned in the May 2006 Subject Report (essential reading on mastery aspects).

.Java has a number of different ways to handle file i/o; any of them are appropriate to SL mastery factors the situation for HL is more complex. The mastery factors for HL are:

adding data to an instance of RandomAccessFile Class
deleting data from an instance of RandomAccessFile Class
searching for specified data in an instance of RandomAccessFile Class
parsing a text file (or other data stream)

The file handling in an HL dossier needs some thought because the requirements of the application will also determine the file structure that is required. This topic will obviously relate to the theory topic, Topic 7. The different structures described there and the links to be found here are:

File Structure Name	Structure Details	Access Method (searching)	Links to Java examples
Sequential file	Ordered or unordered records	Sequential access	The dead simple approach, serialization of an array so the entire thing can be written to file.
Text files	Not in IB Guide	Not in IB Guide	Also a useful way for SL students to do file handling.
Partially-indexed file	Ordered records	Sequential access to index, followed by direct access to the first record in the group, then sequential access to find the desired record.	Example of maintaining an ordered RandomAccessFile .
Fully-indexed file	Unordered records	Sequential access to the index, followed by direct access to the data file.
Direct access file	Unordered or ordered records	A calculation provides the address (location) of a record, followed by direct access to the record.

Searching a data file can be a long process unless a special type of search (binary search) is applied. However, this method can only be applied to sorted collections of records . Therefore searching and sorting will also be included in this section.

These pages were written in a sequence (as indicated by the navigation bar at the bottom of each page, however it is not neccessary to follow this order, hopefully each segment stands alone.

Related: [ Java home | Next: serialization ]

See this page for an example and some further suggestions of using text files in a dossier.

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