Java in a Nutshell, 5th Edition [Electronic resources] نسخه متنی

This class allows you to read and write
arbitrary bytes, text, and primitive Java data types from or to any
specified location in a file. Because this class provides random,
rather than sequential, access to files, it is neither a subclass of
InputStream nor of
OutputStream, but provides an entirely independent
method for reading and writing data from or to files.
RandomAccessFile implements the same interfaces as
DataInputStream and
DataOutputStream, and thus defines the same
methods for reading and writing data as those classes do.

The seek(
) method provides random access to the file; it is used to
select the position in the file where data should be read or written.
The various read and write methods update this file position so that
a sequence of read or write operations can be performed on a
contiguous portion of the file without having to call the
seek( ) method before each read or write.

The mode argument to the constructor
methods should be "r" for a file
that is to be read-only or "rw" for
a file that is to be written (and perhaps read as well). In Java 1.4
and later, two other values for the mode
argument are allowed as well. A mode of
"rwd" opens the file for reading
and writing, and requires that (if the file resides on a local
filesystem) every update to the file content be written synchronously
to the underlying file. The "rws"
mode is similar, but requires synchronous updates to both the
file's content and its metadata (which includes
things such as file access times). Using
"rws" mode may require that the
file metadata be modified every time the file is read.

In Java 1.4 and later, use the getChannel(
)
method to obtain a
FileChannel object that you can use to access the
file using the New I/O API of java.nio and its
subpackages. If the RandomAccessFile was opened
with a mode of "r", the
FileChannel allows only reading. Otherwise, it
allows both reading and writing.

Figure 9-53. java.io.RandomAccessFile

public class

RandomAccessFile implements Closeable, DataInput, DataOutput {
// Public Constructors
public

RandomAccessFile (File

file , String

mode ) throws FileNotFoundException;
public

RandomAccessFile (String

name , String

mode ) throws FileNotFoundException;
// Public Instance Methods
public void

close ( ) throws IOException; Implements:Closeable

1.4 public final java.nio.channels.FileChannel

getChannel ( );
public final FileDescriptor

getFD ( ) throws IOException;
public long

getFilePointer ( ) throws IOException; native
public long

length ( ) throws IOException; native
public int

read ( ) throws IOException; native
public int

read (byte[ ]

b ) throws IOException;
public int

read (byte[ ]

b , int

off , int

len ) throws IOException;
public void

seek (long

pos ) throws IOException; native

1.2 public void

setLength (long

newLength ) throws IOException; native
// Methods Implementing Closeable
public void

close ( ) throws IOException;
// Methods Implementing DataInput
public final boolean

readBoolean ( ) throws IOException;
public final byte

readByte ( ) throws IOException;
public final char

readChar ( ) throws IOException;
public final double

readDouble ( ) throws IOException;
public final float

readFloat ( ) throws IOException;
public final void

readFully (byte[ ]

b ) throws IOException;
public final void

readFully (byte[ ]

b , int

off , int

len ) throws IOException;
public final int

readInt ( ) throws IOException;
public final String

readLine ( ) throws IOException;
public final long

readLong ( ) throws IOException;
public final short

readShort ( ) throws IOException;
public final int

readUnsignedByte ( ) throws IOException;
public final int

readUnsignedShort ( ) throws IOException;
public final String

readUTF ( ) throws IOException;
public int

skipBytes (int

n ) throws IOException;
// Methods Implementing DataOutput
public void

write (int

b ) throws IOException; native
public void

write (byte[ ]

b ) throws IOException;
public void

write (byte[ ]

b , int

off , int

len ) throws IOException;
public final void

writeBoolean (boolean

v ) throws IOException;
public final void

writeByte (int

v ) throws IOException;
public final void

writeBytes (String

s ) throws IOException;
public final void

writeChar (int

v ) throws IOException;
public final void

writeChars (String

s ) throws IOException;
public final void

writeDouble (double

v ) throws IOException;
public final void

writeFloat (float

v ) throws IOException;
public final void

writeInt (int

v ) throws IOException;
public final void

writeLong (long

v ) throws IOException;
public final void

writeShort (int

v ) throws IOException;
public final void

writeUTF (String

str ) throws IOException;
}