The I/O Package - The Java Programming Language - page 799

Creates a random access file stream to read from, and option-
ally write to, the file specified by the File argument. Modes
are the same as for the String -based constructor.
Since accessing a file requires a security check, these constructors could
throw a SecurityException if you do not have permission to access the
file in that modesee " Security " on page 677 .
The "random access" in the name of the class refers to the ability to set
the read/write file pointer to any position in the file and then perform
operations. The additional methods in RandomAccessFile to support this
functionality are:
public long getFilePointer() throws IOException
Returns the current location of the file pointer (in bytes) from
the beginning of the file.
public void seek(long pos) throws IOException
Sets the file pointer to the specified number of bytes from the
beginning of the file. The next byte written or read will be the
pos th byte in the file, where the initial byte is the 0 th . If you
position the file pointer beyond the end of the file and write to
the file, the file will grow.
public int skipBytes(int count) tHRows IOException
Attempts to advance the file pointer count bytes. Any bytes
skipped over can be read later after seek is used to reposition
the file pointer. Returns the actual number of bytes skipped.
This method is guaranteed never to throw an EOFException . If
count is negative, no bytes are skipped.
public long length() throws IOException
Returns the file length.