Minimise accessing the hard disk.
Minimise accessing the underlying operating system.
Minimise processing bytes and characters individually.
1. Use buffering to minimise disk access and underlying operating system. As shown below, with buffering large chunks of a file are read from a disk and then accessed a byte or character at a time. BufferedInputStream, BufferedReader
2. Use the NIO package, if you are using JDK 1.4 or later, which uses performance-enhancing features like buffers to hold data, memory mapping of files, non-blocking I/O operations etc.
3. I/O performance can be improved by minimising the calls to the underlying operating systems. The Java runtime itself cannot know the length of a file, querying the file system for isDirectory(), isFile(), exists() etc must query the underlying operating system.
4. Where applicable caching can be used to improve performance by reading in all the lines of a file into a Java collection class like an ArrayList or a HashMap and subsequently access the data from an in-memory collection instead of the disk.
3. I/O performance can be improved by minimising the calls to the underlying operating systems. The Java runtime itself cannot know the length of a file, querying the file system for isDirectory(), isFile(), exists() etc must query the underlying operating system.
4. Where applicable caching can be used to improve performance by reading in all the lines of a file into a Java collection class like an ArrayList or a HashMap and subsequently access the data from an in-memory collection instead of the disk.
