java.io
class DataInputStream

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

All Implemented Interfaces:

Closeable, DataInput

Most common way to construct:

InputStream in = …;

DataInputStream d = new DataInputStream(in);

Based on 75 examples

public class DataInputStream
extends FilterInputStream
implements DataInput

A data input stream lets an application read primitive Java data types from an underlying input stream in a machine-independent way. An application uses a data output stream to write data that can later be read by a data input stream.

DataInputStream is not necessarily safe for multithreaded access. Thread safety is optional and is the responsibility of users of methods in this class.

See Also (auto-generated):

FileInputStream

InputStream

Thread

DataInputStream

public DataInputStream(InputStream in)

Creates a DataInputStream that uses the specified underlying InputStream.

Parameters:

in - the specified input stream

read

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

Reads some number of bytes from the contained 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.

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

 read(b, 0, b.length) 
 

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is 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 the first byte cannot be read for any reason other than end of file, the stream has been closed and the underlying input stream does not support reading after close, or another I/O error occurs.

read

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

Reads up to len bytes of data from the contained 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 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.

Overrides:

read in class FilterInputStream

Parameters:

b - the buffer into which the data is read.

off - the start offset in the destination array b

len - the maximum number of bytes 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 the first byte cannot be read for any reason other than end of file, the stream has been closed and the underlying input stream does not support reading after close, or another I/O error occurs.

readBoolean

public final boolean readBoolean()
                          throws IOException

See the general contract of the readBoolean method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the boolean value read.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readByte

public final byte readByte()
                    throws IOException

See the general contract of the readByte method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next byte of this input stream as a signed 8-bit byte.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readChar

public final char readChar()
                    throws IOException

See the general contract of the readChar method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next two bytes of this input stream, interpreted as a char.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readDouble

public final double readDouble()
                        throws IOException

See the general contract of the readDouble method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next eight bytes of this input stream, interpreted as a double.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readFloat

public final float readFloat()
                      throws IOException

See the general contract of the readFloat method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next four bytes of this input stream, interpreted as a float.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readFully

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

See the general contract of the readFully method of DataInput.

Bytes for this operation are read from the contained input stream.

Parameters:

b - the buffer into which the data is read.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readFully

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

See the general contract of the readFully method of DataInput.

Bytes for this operation are read from the contained input stream.

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the number of bytes to read.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readInt

public final int readInt()
                  throws IOException

See the general contract of the readInt method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next four bytes of this input stream, interpreted as an int.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readLine

public final String readLine()
                      throws IOException

See the general contract of the readLine method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next line of text from this input stream.

Throws:

IOException - if an I/O error occurs.

readLong

public final long readLong()
                    throws IOException

See the general contract of the readLong method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next eight bytes of this input stream, interpreted as a long.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readShort

public final short readShort()
                      throws IOException

See the general contract of the readShort method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next two bytes of this input stream, interpreted as a signed 16-bit number.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readUnsignedByte

public final int readUnsignedByte()
                           throws IOException

See the general contract of the readUnsignedByte method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next byte of this input stream, interpreted as an unsigned 8-bit number.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readUnsignedShort

public final int readUnsignedShort()
                            throws IOException

See the general contract of the readUnsignedShort method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

the next two bytes of this input stream, interpreted as an unsigned 16-bit integer.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readUTF

public final String readUTF()
                     throws IOException

See the general contract of the readUTF method of DataInput.

Bytes for this operation are read from the contained input stream.

Returns:

a Unicode string.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

readUTF

public static final String readUTF(DataInput in)
                            throws IOException

Reads from the stream in a representation of a Unicode character string encoded in modified UTF-8 format; this string of characters is then returned as a String. The details of the modified UTF-8 representation are exactly the same as for the readUTF method of DataInput.

Parameters:

in - a data input stream.

Returns:

a Unicode string.

Throws:

IOException - the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

skipBytes

public final int skipBytes(int n)
                    throws IOException

See the general contract of the skipBytes method of DataInput.

Bytes for this operation are read from the contained input stream.

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if the contained input stream does not support seek, or the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.