At what file size is it advisable to start applying optimization methods to improve efficiency?

Optimization of file handling is usually applied when the file size becomes large enough to noticeably affect performance and resource usage. In Java, there is no specific universal threshold, but optimizations are often considered when working with files of several megabytes (for example, 10 MB and above).

Reasons for optimization:

• Reading or writing large files entirely into memory can lead to high RAM consumption.
• Long processing times due to inefficient I/O operations.

Typical optimization methods:

• Using stream-based reading/writing (BufferedInputStream, BufferedOutputStream).
• Reading the file in chunks rather than entirely.
• Using NIO (java.nio) for more efficient input/output.

Example of reading a file in chunks using BufferedReader:

try (BufferedReader reader = new BufferedReader(new FileReader("largefile.txt"))) {
    String line;
    while ((line = reader.readLine()) != null) {
        // Process the line
    }
}