RandomAccessFile

While FileInputStreams are useful for reading files sequentially, RandomAccessFiles allow users to access files in a non-sequential fashion.

RandomAccessFile classes are instantiated using ‘r’ or ‘rw’ mode to specify read or read-write access, respectively. One of the following constructors may be used:

• RandomAccessFile(String name, String mode)
• RandomAccessFile(File file, String mode)

Like FileInputStream and FileOutputStream, RandomAccessFiles support the baseline read and write methods. Several methods are available to work with RandomAccessFile objects.

• long getFilePointer();
• void seek(long startpos);
• long length();

The getFilePointer() method returns the current location of the file pointer within a file. The seek() method sets the file pointer to a particular location within the file. The length() method returns the length of the file. As shown in the diagram, all read/write operations on Java primitive types are implemented through the DataInput and DataOutput interfaces.