Summary: Inherited Fields | Ctors | Methods | Inherited Methods | [Expand All]

public class

DataInputStream

extends FilterInputStream
implements DataInput

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

Class Overview

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.

Summary

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Inherited Fields

From class java.io.FilterInputStream

Public Constructors
	DataInputStream(InputStream in) Creates a DataInputStream that uses the specified underlying InputStream.

Public Methods
final int	read(byte[] b, int off, int len) Reads up to `len` bytes of data from the contained input stream into an array of bytes.
final int	read(byte[] b) Reads some number of bytes from the contained input stream and stores them into the buffer array `b`.
final boolean	readBoolean() See the general contract of the `readBoolean` method of `DataInput`.
final byte	readByte() See the general contract of the `readByte` method of `DataInput`.
final char	readChar() See the general contract of the `readChar` method of `DataInput`.
final double	readDouble() See the general contract of the `readDouble` method of `DataInput`.
final float	readFloat() See the general contract of the `readFloat` method of `DataInput`.
final void	readFully(byte[] b) See the general contract of the `readFully` method of `DataInput`.
final void	readFully(byte[] b, int off, int len) See the general contract of the `readFully` method of `DataInput`.
final int	readInt() See the general contract of the `readInt` method of `DataInput`.
final String	readLine() This method is deprecated. This method does not properly convert bytes to characters. As of JDK 1.1, the preferred way to read lines of text is via the `BufferedReader.readLine()` method. Programs that use the `DataInputStream` class to read lines can be converted to use the `BufferedReader` class by replacing code of the form: DataInputStream d = new DataInputStream(in); with: BufferedReader d = new BufferedReader(new InputStreamReader(in));
final long	readLong() See the general contract of the `readLong` method of `DataInput`.
final short	readShort() See the general contract of the `readShort` method of `DataInput`.
final static String	readUTF(DataInput in) 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`.
final String	readUTF() See the general contract of the `readUTF` method of `DataInput`.
final int	readUnsignedByte() See the general contract of the `readUnsignedByte` method of `DataInput`.
final int	readUnsignedShort() See the general contract of the `readUnsignedShort` method of `DataInput`.
final int	skipBytes(int n) See the general contract of the `skipBytes` method of `DataInput`.

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Inherited Methods

From class java.io.FilterInputStream

int	available() Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
void	close() Closes this input stream and releases any system resources associated with the stream.
synchronized void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the `mark` and `reset` methods.
int	read(byte[] b) Reads up to `byte.length` bytes of data from this input stream into an array of bytes.
int	read() Reads the next byte of data from this input stream.
int	read(byte[] b, int off, int len) Reads up to `len` bytes of data from this input stream into an array of bytes.
synchronized void	reset() Repositions this stream to the position at the time the `mark` method was last called on this input stream.
long	skip(long n) Skips over and discards `n` bytes of data from this input stream. This method simply performs `in.skip(n)`.

From class java.io.InputStream

int	available() Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream.
void	close() Closes this input stream and releases any system resources associated with the stream.
synchronized void	mark(int readlimit) Marks the current position in this input stream.
boolean	markSupported() Tests if this input stream supports the `mark` and `reset` methods.
int	read(byte[] b) Reads some number of bytes from the input stream and stores them into the buffer array `b`.
abstract int	read() Reads the next byte of data from the input stream.
int	read(byte[] b, int off, int len) Reads up to `len` bytes of data from the input stream into an array of bytes.
synchronized void	reset() Repositions this stream to the position at the time the `mark` method was last called on this input stream.
long	skip(long n) Skips over and discards `n` bytes of data from this input stream.

From class java.lang.Object

Object	clone() Creates and returns a copy of this object.
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
final Class<?>	getClass() Returns the runtime class of this `Object`.
int	hashCode() Returns a hash code value for the object.
final void	notify() Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll() Wakes up all threads that are waiting on this object's monitor.
String	toString() Returns a string representation of the object.
final void	wait() Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object.
final void	wait(long timeout, int nanos) Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
final void	wait(long timeout) Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.

From interface java.io.Closeable

From interface java.io.DataInput

abstract boolean	readBoolean() Reads one input byte and returns `true` if that byte is nonzero, `false` if that byte is zero.
abstract byte	readByte() Reads and returns one input byte.
abstract char	readChar() Reads two input bytes and returns a `char` value.
abstract double	readDouble() Reads eight input bytes and returns a `double` value.
abstract float	readFloat() Reads four input bytes and returns a `float` value.
abstract void	readFully(byte[] b) Reads some bytes from an input stream and stores them into the buffer array `b`.
abstract void	readFully(byte[] b, int off, int len) Reads `len` bytes from an input stream.
abstract int	readInt() Reads four input bytes and returns an `int` value.
abstract String	readLine() Reads the next line of text from the input stream.
abstract long	readLong() Reads eight input bytes and returns a `long` value.
abstract short	readShort() Reads two input bytes and returns a `short` value.
abstract String	readUTF() Reads in a string that has been encoded using a modified UTF-8 format.
abstract int	readUnsignedByte() Reads one input byte, zero-extends it to type `int`, and returns the result, which is therefore in the range `0` through `255`.
abstract int	readUnsignedShort() Reads two input bytes and returns an `int` value in the range `0` through `65535`.
abstract int	skipBytes(int n) Makes an attempt to skip over `n` bytes of data from the input stream, discarding the skipped bytes.

Public Constructors

public DataInputStream (InputStream in)

Creates a DataInputStream that uses the specified underlying InputStream.

Parameters

in	the specified input stream

Public Methods

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

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.

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

NullPointerException	If `b` is `null`.
IndexOutOfBoundsException	If `off` is negative, `len` is negative, or `len` is greater than `b.length - off`
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.

public final int read (byte[] b)

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)

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.

public final boolean readBoolean ()

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

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

public final byte readByte ()

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

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

public final char readChar ()

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

EOFException	if this input stream reaches the end before reading two bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public final double readDouble ()

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

EOFException	if this input stream reaches the end before reading eight bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public final float readFloat ()

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

EOFException	if this input stream reaches the end before reading four bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public final void readFully (byte[] b)

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

EOFException	if this input stream reaches the end before reading all the bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

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

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

EOFException	if this input stream reaches the end before reading all the bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public final int readInt ()

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

EOFException	if this input stream reaches the end before reading four bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public final String readLine ()

This method is deprecated.
This method does not properly convert bytes to characters. As of JDK 1.1, the preferred way to read lines of text is via the BufferedReader.readLine() method. Programs that use the DataInputStream class to read lines can be converted to use the BufferedReader class by replacing code of the form:

     DataInputStream d = new DataInputStream(in);

with:

     BufferedReader d
          = new BufferedReader(new InputStreamReader(in));

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.

public final long readLong ()

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

EOFException	if this input stream reaches the end before reading eight bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public final short readShort ()

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

EOFException	if this input stream reaches the end before reading two bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public static final String readUTF (DataInput in)

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

EOFException	if the input stream reaches the end before all the bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
UTFDataFormatException	if the bytes do not represent a valid modified UTF-8 encoding of a Unicode string.

public final String readUTF ()

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

EOFException	if this input stream reaches the end before reading all the bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
UTFDataFormatException	if the bytes do not represent a valid modified UTF-8 encoding of a string.

public final int readUnsignedByte ()

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

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

public final int readUnsignedShort ()

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

EOFException	if this input stream reaches the end before reading two bytes.
IOException	the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.

public final int skipBytes (int n)

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.

Interfaces

Classes

Exceptions

Errors

DataInputStream

Class Overview

See Also

Summary

Public Constructors

public DataInputStream (InputStream in)

Parameters

Public Methods

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

Parameters

Returns

Throws

See Also

public final int read (byte[] b)

Parameters

Returns

Throws

See Also

public final boolean readBoolean ()

Returns

Throws

See Also

public final byte readByte ()

Returns

Throws

See Also

public final char readChar ()

Returns

Throws

See Also

public final double readDouble ()

Returns

Throws

See Also

public final float readFloat ()

Returns

Throws

See Also

public final void readFully (byte[] b)

Parameters

Throws

See Also

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

Parameters

Throws

See Also

public final int readInt ()

Returns

Throws

See Also

public final String readLine ()

Returns

Throws

See Also

public final long readLong ()

Returns

Throws

See Also

public final short readShort ()

Returns

Throws

See Also

public static final String readUTF (DataInput in)

Parameters

Returns

Throws

See Also

public final String readUTF ()

Returns

Throws

See Also

public final int readUnsignedByte ()

Returns

Throws

See Also

public final int readUnsignedShort ()