java.lang.Object java.io.InputStream java.io.FilterInputStream 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.
Data input streams and data output streams represent Unicode strings in a format that is a slight modification of UTF-8. (For more information, see X/Open Company Ltd., "File System Safe UCS Transformation Format (FSS_UTF)", X/Open Preliminary Specification, Document Number: P316. This information also appears in ISO/IEC 10646, Annex P.) Note that in the following tables, the most significant bit appears in the far left-hand column.
All characters in the range '\u0001' to '\u007F' are represented by a single byte:
Bit Values |
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Byte 1 | 0 | bits 6-0 |
The null character '\u0000' and characters in the range '\u0080' to '\u07FF' are represented by a pair of bytes:
Bit Values |
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Byte 1 | 1 | 1 | 0 | bits 10-6 |
Byte 2 | 1 | 0 | bits 5-0 |
Bit Values |
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Byte 1 | 1 | 1 | 1 | 0 | bits 15-12 |
Byte 2 | 1 | 0 | bits 11-6 | ||
Byte 3 | 1 | 0 | bits 5-0 |
The two differences between this format and the "standard" UTF-8 format are the following:
Field Summary |
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Fields inherited from class java.io. FilterInputStream |
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in |
Constructor Summary | |
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DataInputStream
(
InputStream
in) Creates a DataInputStream that uses the specified underlying InputStream. |
Method Summary | |
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int |
read
(byte[] b) Reads some number of bytes from the contained 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 contained input stream into an array of bytes. |
boolean |
readBoolean
() See the general contract of the readBoolean method of DataInput. |
byte |
readByte
() See the general contract of the readByte method of DataInput. |
char |
readChar
() See the general contract of the readChar method of DataInput. |
double |
readDouble
() See the general contract of the readDouble method of DataInput. |
float |
readFloat
() See the general contract of the readFloat method of DataInput. |
void |
readFully
(byte[] b) See the general contract of the readFully method of DataInput. |
void |
readFully
(byte[] b, int off, int len) See the general contract of the readFully method of DataInput. |
int |
readInt
() See the general contract of the readInt method of DataInput. |
String |
readLine
() 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: with:DataInputStream d = new DataInputStream(in); BufferedReader d = new BufferedReader(new InputStreamReader(in)); |
long |
readLong
() See the general contract of the readLong method of DataInput. |
short |
readShort
() See the general contract of the readShort method of DataInput. |
int |
readUnsignedByte
() See the general contract of the readUnsignedByte method of DataInput. |
int |
readUnsignedShort
() See the general contract of the readUnsignedShort method of DataInput. |
String |
readUTF
() See the general contract of the readUTF method of DataInput. |
static String |
readUTF
(
DataInput
in) Reads from the stream in a representation of a Unicode character string encoded in Java modified UTF-8 format; this string of characters is then returned as a String. |
int |
skipBytes
(int n) See the general contract of the skipBytes method of DataInput. |
Methods inherited from class java.io. FilterInputStream |
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available , close , mark , markSupported , read , reset , skip |
Methods inherited from class java.lang. Object |
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clone , equals , finalize , getClass , hashCode , notify , notifyAll , toString , wait , wait , wait |
Constructor Detail |
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public DataInputStream(InputStream in)
Method Detail |
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public final int read(byte[] b) throws IOException
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)
public final int read(byte[] b, int off, int len) throws IOException
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.
public final void readFully(byte[] b) throws IOException
Bytes for this operation are read from the contained input stream.
public final void readFully(byte[] b, int off, int len) throws IOException
Bytes for this operation are read from the contained input stream.
public final int skipBytes(int n) throws IOException
Bytes for this operation are read from the contained input stream.
public final boolean readBoolean() throws IOException
Bytes for this operation are read from the contained input stream.
public final byte readByte() throws IOException
Bytes for this operation are read from the contained input stream.
public final int readUnsignedByte() throws IOException
Bytes for this operation are read from the contained input stream.
public final short readShort() throws IOException
Bytes for this operation are read from the contained input stream.
public final int readUnsignedShort() throws IOException
Bytes for this operation are read from the contained input stream.
public final char readChar() throws IOException
Bytes for this operation are read from the contained input stream.
public final int readInt() throws IOException
Bytes for this operation are read from the contained input stream.
public final long readLong() throws IOException
Bytes for this operation are read from the contained input stream.
public final float readFloat() throws IOException
Bytes for this operation are read from the contained input stream.
public final double readDouble() throws IOException
Bytes for this operation are read from the contained input stream.
public final String readLine() throws IOException
with:DataInputStream d = new DataInputStream(in);
BufferedReader d = new BufferedReader(new InputStreamReader(in));
Bytes for this operation are read from the contained input stream.
public final String readUTF() throws IOException
Bytes for this operation are read from the contained input stream.
public static final String readUTF(DataInput in) throws IOException