File I/O - Absolute Java - page 635

Display 10.21 Some Methods of the Class RandomAccessFile (part 3 of 3)

public final int readInt) throws IOException

Reads an int value from the file and returns that value. If an attempt is made to read beyond the
end of the file, an EOFException is thrown.

public final long readLong() throws IOException

Reads a long value from the file and returns that value. If an attempt is made to read beyond the
end of the file, an EOFException is thrown.

public final double readDouble() throws IOException

Reads a double value from the file and returns that value. If an attempt is made to read beyond
the end of the file, an EOFException is thrown.

public final float readFloat() throws IOException

Reads a float value from the file and returns that value. If an attempt is made to read beyond
the end of the file, an EOFException is thrown.

public final char readChar() throws IOException

Reads a char value from the file and returns that value. If an attempt is made to read beyond the
end of the file, an EOFException is thrown.

public final boolean readBoolean() throws IOException

Reads a boolean value from the file and returns that value. If an attempt is made to read beyond
the end of the file, an EOFException is thrown.

public final String readUTF() throws IOException

Reads a String value from the file and returns that value. If an attempt is made to read beyond
the end of the file, an EOFException is thrown.

readUTF , and so on. However, the class RandomAccessFile does not have the
methods writeObject or readObject . The most important methods of the class
RandomAccessFile are given in Display 10.21. A demonstration program for random
access files is given in Display 10.22 .
The constructor for RandomAccessFile takes either a string name for the file or
an object of the class File as its first argument. The second argument must be one of
the four strings "rw" , "r" , and two modes we do not discuss in this topic, "rws" and
"rwd" . The string "rw" means your code can both read and write to the file after it is
open. The string "r" means your code can read from the file but cannot write to the file.
If the file already exists, then when it is opened, the length is not reset to 0 , but the
file pointer will be positioned at the start of the file, which is what you would expect at
least for "r" . If the length of the file is not what you want, you can change it with the
method setLength . In particular, you can use setLength to empty the file.

opening a file