java.io
Class DataInputStream

java.lang.Object
  java.io.InputStream
      java.io.DataInputStream

public class DataInputStream
extends InputStream

Reads java data types transmitted as bytes over an InputStream.

Author:

Sven Köhler

Field Summary

protected InputStream

in

Constructor Summary

DataInputStream(InputStream in)

Method Summary

void	close() Closes this input stream and releases any system resources associated with the stream.
int	read() Reads the next byte of data from this input stream.
int	read(byte[] b) Reads some number of bytes from the input stream and stores them into the buffer array b.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
boolean	readBoolean()
byte	readByte()
char	readChar()
double	readDouble()
float	readFloat()
void	readFully(byte[] b)
void	readFully(byte[] b, int off, int len)
int	readInt()
String	readLine() Deprecated. broken in various ways, use BufferedReader.readLine instead
long	readLong()
short	readShort()
int	readUnsignedByte()
int	readUnsignedShort()
int	skipBytes(int n)

Methods inherited from class java.io.InputStream

available, mark, markSupported, reset, skip

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

in

protected InputStream in

Constructor Detail

DataInputStream

public DataInputStream(InputStream in)

Method Detail

read

public int read()
         throws IOException

Reads the next byte of data from this input stream. The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

This method simply performs in.read() and returns the result.

Specified by:

read in class InputStream

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

IOException - if an I/O error occurs.

See Also:

java.io.FilterInputStream#in

read

public final int read(byte[] b)
               throws IOException

Description copied from class: InputStream

Reads some number of bytes from the input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown. If the length of b is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b) method for class InputStream has the same effect as:

 read(b, 0, b.length) 

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

See Also:

InputStream.read(byte[], int, int)

read

public final int read(byte[] b,
                      int off,
                      int len)
               throws IOException

Description copied from class: InputStream

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer.

This method blocks until input data is available, end of file is detected, or an exception is thrown.

If b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException is thrown.

If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.

The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.

In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. Subclasses are encouraged to provide a more efficient implementation of this method.

Overrides:

read in class InputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in array b at which the data is written.

len - the maximum number of bytes to read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

See Also:

InputStream.read()

readBoolean

public final boolean readBoolean()
                          throws IOException

Throws:

IOException

readByte

public final byte readByte()
                    throws IOException

Throws:

IOException

readChar

public final char readChar()
                    throws IOException

Throws:

IOException

readDouble

public final double readDouble()
                        throws IOException

Throws:

IOException

readFloat

public final float readFloat()
                      throws IOException

Throws:

IOException

readFully

public final void readFully(byte[] b)
                     throws IOException

Throws:

IOException

readFully

public final void readFully(byte[] b,
                            int off,
                            int len)
                     throws IOException

Throws:

IOException

readInt

public final int readInt()
                  throws IOException

Throws:

IOException

readLong

public final long readLong()
                    throws IOException

Throws:

IOException

readShort

public final short readShort()
                      throws IOException

Throws:

IOException

readUnsignedByte

public final int readUnsignedByte()
                           throws IOException

Throws:

IOException

readUnsignedShort

public final int readUnsignedShort()
                            throws IOException

Throws:

IOException

skipBytes

public final int skipBytes(int n)
                    throws IOException

Throws:

IOException

readLine

@Deprecated
public final String readLine()
                      throws IOException

Deprecated. broken in various ways, use BufferedReader.readLine instead

Deprecated. This method assumes ISO-8859-1 encoding and does only recognize \n and \r\n line-endings.

Throws:

IOException

close

public void close()
           throws IOException

Description copied from class: InputStream

Closes this input stream and releases any system resources associated with the stream.

The close method of InputStream does nothing.

Overrides:

close in class InputStream

Throws:

IOException - if an I/O error occurs.