Class: java.io.DataInputStream

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.

Authors:
@author Arthur van Hoff
See:
@see java.io.DataOutputStream
Since:
@since JDK1.0

Inheritance

Superclass tree: Implements:

Methods

  • DataInputStreamtop

    public DataInputStream(InputStream in)
    Creates a DataInputStream that uses the specified underlying InputStream.
    Parameters:
    @param in the specified input stream
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  • readtop

    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)
    Parameters:
    @param b the buffer into which the data is read.
    Return:
    @return 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.
    Exceptions:
    @exception 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.
    See:
    @see java.io.FilterInputStream.in
    @see java.io.InputStream.read(byte[], int, int)
    Override hierarchy:
    read from FilterInputStream
    read from InputStream
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  • readtop

    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.

    Parameters:
    @param b the buffer into which the data is read.
    @param off the start offset in the destination array b
    @param len the maximum number of bytes read.
    Return:
    @return 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.
    Exceptions:
    @exception NullPointerException If b is null.
    @exception IndexOutOfBoundsException If off is negative, len is negative, or len is greater than b.length - off
    @exception 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.
    See:
    @see java.io.FilterInputStream.in
    @see java.io.InputStream.read(byte[], int, int)
    Override hierarchy:
    read from FilterInputStream
    read from InputStream
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  • readBooleantop

    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.

    Return:
    @return the boolean value read.
    Exceptions:
    @exception EOFException if this input stream has reached the end.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readBoolean from DataInput
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  • readBytetop

    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.

    Return:
    @return the next byte of this input stream as a signed 8-bit byte.
    Exceptions:
    @exception EOFException if this input stream has reached the end.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readByte from DataInput
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  • readChartop

    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.

    Return:
    @return the next two bytes of this input stream, interpreted as a char.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading two bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readChar from DataInput
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  • readDoubletop

    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.

    Return:
    @return the next eight bytes of this input stream, interpreted as a double.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading eight bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.DataInputStream.readLong()
    @see Double.longBitsToDouble(long)
    Specified by:
    readDouble from DataInput
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  • readFloattop

    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.

    Return:
    @return the next four bytes of this input stream, interpreted as a float.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading four bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.DataInputStream.readInt()
    @see Float.intBitsToFloat(int)
    Specified by:
    readFloat from DataInput
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  • readFullytop

    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:
    @param b the buffer into which the data is read.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading all the bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readFully from DataInput
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  • readFullytop

    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:
    @param b the buffer into which the data is read.
    @param off the start offset of the data.
    @param len the number of bytes to read.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading all the bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readFully from DataInput
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  • readInttop

    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.

    Return:
    @return the next four bytes of this input stream, interpreted as an int.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading four bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readInt from DataInput
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  • readLinetop

    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.

    Return:
    @return the next line of text from this input stream.
    Exceptions:
    @exception IOException if an I/O error occurs.
    Deprecated:
    @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:
    @see java.io.BufferedReader.readLine()
    @see java.io.FilterInputStream.in
    Specified by:
    readLine from DataInput
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  • readLongtop

    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.

    Return:
    @return the next eight bytes of this input stream, interpreted as a long.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading eight bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readLong from DataInput
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  • readShorttop

    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.

    Return:
    @return the next two bytes of this input stream, interpreted as a signed 16-bit number.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading two bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readShort from DataInput
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  • readUTFtop

    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.

    Return:
    @return a Unicode string.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading all the bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    @exception UTFDataFormatException if the bytes do not represent a valid modified UTF-8 encoding of a string.
    See:
    @see java.io.DataInputStream.readUTF(java.io.DataInput)
    Specified by:
    readUTF from DataInput
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  • readUTFtop

    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:
    @param in a data input stream.
    Return:
    @return a Unicode string.
    Exceptions:
    @exception EOFException if the input stream reaches the end before all the bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    @exception UTFDataFormatException if the bytes do not represent a valid modified UTF-8 encoding of a Unicode string.
    See:
    @see java.io.DataInputStream.readUnsignedShort()
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  • readUnsignedBytetop

    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.

    Return:
    @return the next byte of this input stream, interpreted as an unsigned 8-bit number.
    Exceptions:
    @exception EOFException if this input stream has reached the end.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readUnsignedByte from DataInput
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  • readUnsignedShorttop

    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.

    Return:
    @return the next two bytes of this input stream, interpreted as an unsigned 16-bit integer.
    Exceptions:
    @exception EOFException if this input stream reaches the end before reading two bytes.
    @exception IOException the stream has been closed and the contained input stream does not support reading after close, or another I/O error occurs.
    See:
    @see java.io.FilterInputStream.in
    Specified by:
    readUnsignedShort from DataInput
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  • skipBytestop

    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:
    @param n the number of bytes to be skipped.
    Return:
    @return the actual number of bytes skipped.
    Exceptions:
    @exception 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.
    Specified by:
    skipBytes from DataInput
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