Java FileInputStream

📂 Java FileInputStream

FileInputStream is a byte stream class used to read raw byte data from a file.
It is mainly used for binary files like images, videos, or any non-text files, but can also read text files.

  • Package: java.io

  • Superclass: InputStream

✅ Syntax


1. Reading a File Byte by Byte


 

  • Reads one byte at a time.

  • Returns -1 when end-of-file (EOF) is reached.

2. Reading Multiple Bytes into a Byte Array


 

  • More efficient than reading byte by byte.

  • Converts bytes to string using new String(buffer, 0, bytesRead).

3. Reading a Binary File (Example: Image)


 

  • Reads binary data efficiently using a buffer.

  • Useful for copying files, images, audio, etc.

4. Important Methods

Method Description
read() Reads one byte; returns -1 at EOF
read(byte[] b) Reads multiple bytes into array
available() Returns number of bytes that can be read without blocking
close() Closes the stream to release system resources

✅ Best Practices

  1. Always close the stream after usage (use try-with-resources).

  2. Use buffers for reading large files to improve performance.

  3. Handle IOException properly.

Summary

  • FileInputStream = byte stream → suitable for binary files

  • Read byte by byte or in chunks using a byte array.

  • Use try-with-resources to automatically close streams.

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