DataInputStream (Java 2 Platform SE 5.0) (original) (raw)

java.io

Class DataInputStream

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

All Implemented Interfaces:

Closeable, DataInput

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.

Since:

JDK1.0

See Also:

DataOutputStream

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.

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 has the same effect as:

read(b, 0, b.length)

Overrides:

[read](../../java/io/FilterInputStream.html#read%28byte[]%29) in class [FilterInputStream](../../java/io/FilterInputStream.html "class in java.io")

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](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in, [InputStream.read(byte[], int, int)](../../java/io/InputStream.html#read%28byte[], int, int%29)

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 b is null, aNullPointerException is thrown.

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

If len is zero, then no bytes are read and0 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 elementsb[off] through b[off+k-1], leaving elements b[off+k] throughb[off+len-1] unaffected.

In every case, elements b[0] throughb[off] and elements b[off+len] throughb[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, anIOException is thrown if the input stream has been closed.

Overrides:

[read](../../java/io/FilterInputStream.html#read%28byte[], int, int%29) in class [FilterInputStream](../../java/io/FilterInputStream.html "class in java.io")

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

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](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in, [InputStream.read(byte[], int, int)](../../java/io/InputStream.html#read%28byte[], int, int%29)

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.

Specified by:

[readFully](../../java/io/DataInput.html#readFully%28byte[]%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Parameters:

b - the buffer into which the data is read.

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading all the bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readFully](../../java/io/DataInput.html#readFully%28byte[], int, int%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

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](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading all the bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[skipBytes](../../java/io/DataInput.html#skipBytes%28int%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

[IOException](../../java/io/IOException.html "class in java.io") - if an 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.

Specified by:

[readBoolean](../../java/io/DataInput.html#readBoolean%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

the boolean value read.

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream has reached the end.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readByte](../../java/io/DataInput.html#readByte%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream has reached the end.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readUnsignedByte](../../java/io/DataInput.html#readUnsignedByte%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream has reached the end.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readShort](../../java/io/DataInput.html#readShort%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading two bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readUnsignedShort](../../java/io/DataInput.html#readUnsignedShort%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading two bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readChar](../../java/io/DataInput.html#readChar%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

the next two bytes of this input stream as a Unicode character.

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading two bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readInt](../../java/io/DataInput.html#readInt%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading four bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readLong](../../java/io/DataInput.html#readLong%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading eight bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

FilterInputStream.in

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.

Specified by:

[readFloat](../../java/io/DataInput.html#readFloat%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading four bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

readInt(), Float.intBitsToFloat(int)

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.

Specified by:

[readDouble](../../java/io/DataInput.html#readDouble%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

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

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading eight bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

readLong(), Double.longBitsToDouble(long)

readLine

@Deprecated public final String readLine() throws IOException

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 theBufferedReader.readLine() method. Programs that use theDataInputStream 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.

Specified by:

[readLine](../../java/io/DataInput.html#readLine%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

the next line of text from this input stream.

Throws:

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

See Also:

BufferedReader.readLine(), FilterInputStream.in

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.

Specified by:

[readUTF](../../java/io/DataInput.html#readUTF%28%29) in interface [DataInput](../../java/io/DataInput.html "interface in java.io")

Returns:

a Unicode string.

Throws:

[EOFException](../../java/io/EOFException.html "class in java.io") - if this input stream reaches the end before reading all the bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

[UTFDataFormatException](../../java/io/UTFDataFormatException.html "class in java.io") - if the bytes do not represent a valid modified UTF-8 encoding of a string.

See Also:

readUTF(java.io.DataInput)

readUTF

public static final String readUTF(DataInput in) throws IOException

Reads from the stream in a representation of a Unicode character string encoded inmodified 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](../../java/io/EOFException.html "class in java.io") - if the input stream reaches the end before all the bytes.

[IOException](../../java/io/IOException.html "class in java.io") - if an I/O error occurs.

[UTFDataFormatException](../../java/io/UTFDataFormatException.html "class in java.io") - if the bytes do not represent a valid modified UTF-8 encoding of a Unicode string.

See Also:

readUnsignedShort()

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For further API reference and developer documentation, see Java 2 SDK SE Developer Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.

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