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Chapter 11 The java.io Package |
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Chapter 11 The java.io Package |
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java.io.DataInputStream
java.io.FilterInputStream
None
java.io.DataInput
JDK 1.0 or later
The DataInputStream class provides methods for reading primitive data types and lines of text from an underlying input stream in a machine-independent manner. Many of the methods of DataInputStream read a single primitive data type, in binary format, from an underlying input stream. All multibyte quantities are assumed to be in a format that stores the most significant byte as the first byte and the least significant byte as the last byte.
public class java.io.DataInputStream extends java.io.FilterInputStream
implements java.io.DataInput {
// Constructors
public DataInputStream(InputStream in);
// Class Methods
public final static String readUTF(DataInput in);
// Instance Methods
public final int read(byte[] b);
public final int read(byte[] b, int off, int len);
public final boolean readBoolean();
public final byte readByte();
public final char readChar();
public final double readDouble();
public final float readFloat();
public final void readFully(byte[] b);
public final void readFully(byte[] b, int off, int len);
public final int readInt();
public final String readLine(); // Deprecated in 1.1
public final long readLong();
public final short readShort();
public final int readUnsignedByte();
public final int readUnsignedShort();
public final String readUTF() throws IOException;
public final int skipBytes(int n) throws IOException;
}
The input stream to use.
This constructor creates a DataInputStream object that reads from, or wraps, the given input stream.
public final static String readUTF(DataInput in) throws IOException
The data input stream to use.
The String read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
If the bytes do not represent a valid UTF-8 encoding.
This method reads a UTF-8 encoded string from the given DataInput object. To get the number of bytes in the encoded string, the first two bytes are read as an unsigned short value. Then the following bytes are read and interpreted as UTF-8 encoded bytes; these bytes are converted into characters for the resulting String. This method blocks until all of the bytes in the encoded string have been read, the end of the stream is encountered, or an exception is thrown.
For details on the UTF-8 encoding, see Appendix B, The UTF-8 Encoding.
An array of bytes to be filled from the stream.
The number of bytes read, or -1 if the end of file is encountered immediately.
If any kind of I/O error occurs.
FilterInputStream.read(byte[])
This method reads bytes of input into the given array by calling the read() method of the underlying stream. The method reads up to b.length bytes of data from the stream. The method blocks until there is some input available.
public final int read(byte b[], int off, int len) throws IOException
An array of bytes to be filled from the stream.
An offset into the byte array.
The number of bytes to read.
The number of bytes read, or -1 if the end of file is encountered immediately.
If any kind of I/O error occurs.
FilterInputStream.read(byte[], int, int)
This method reads up to len bytes of input into the given array starting at index off. The method reads the bytes by calling the read() method of the underlying stream and blocks until there is some input available.
The boolean value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readBoolean()
This method reads a byte as a boolean value from the underlying input stream. A byte that contains a zero is read as false; that which contains any other value is read as true. The method blocks until the byte is read, the end of the stream is encountered, or an exception is thrown.
The byte value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readByte()
This method reads a signed 8-bit value--a byte--from the underlying input stream. The method blocks until the byte is read, the end of the stream is encountered, or an exception is thrown.
The char value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readChar()
This method reads a 16-bit Unicode character from the stream. The method reads two bytes from the underlying input stream and then creates a char value, using the first byte read as the most significant byte. The method blocks until the two bytes are read, the end of the stream is encountered, or an exception is thrown.
The double value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readDouble()
This method reads a 64-bit double quantity from the stream. The method reads a long value from the underlying input stream as if using the readLong() method. The long value is then converted to a double using the longBitsToDouble() method in Double. The method blocks until the necessary eight bytes are read, the end of the stream is encountered, or an exception is thrown.
The float value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readFloat()
This method reads a 32-bit float quantity from the stream. The method reads an int value from the underlying input stream as if using the readInt() method. The int value is then converted to a float using the intBitsToFloat() method in Float. The method blocks until the necessary four bytes are read, the end of the stream is encountered, or an exception is thrown.
The array to fill.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readFully(byte[])
This method reads bytes into the given array b until the array is full. The method reads repeatedly from the underlying stream to fill the array. The method blocks until all of the bytes are read, the end of the stream is encountered, or an exception is thrown.
public final void readFully(byte b[], int off, int len) throws IOException
The array to fill.
An offset into the array.
The number of bytes to read.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readFully(byte[], int, int)
This method reads len bytes into the given array, starting at offset off. The method reads repeatedly from the underlying stream to fill the array. The method blocks until all the bytes are read, the end of the stream is encountered, or an exception is thrown.
The int value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readInt()
This method reads a signed 32-bit int quantity from the stream. The method reads four bytes from the underlying input stream and then creates an int quantity, using the first byte read as the most significant byte. The method blocks until the four bytes are read, the end of the stream is encountered, or an exception is thrown.
Deprecated as of JDK 1.1
A String that contains the line read from the stream.
If the end of the file is encountered.
If any other I/O error occurs.
DataInput.readLine()
This method reads the next line of text from the stream. The method reads bytes of data from the underlying input stream until it encounters a line terminator. A line terminator is a carriage return ("\r"), a newline character ("\n"), a carriage return immediately followed by a newline character, or the end of the stream. The method blocks until a line terminator is read, the end of the stream is encountered, or an exception is thrown.
This method is deprecated as of JDK 1.1 because it does not convert bytes to characters correctly. It's replaced by BufferedReader.readLine().
The long value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readLong()
This method reads a signed 64-bit long quantity from the stream. The method reads eight bytes from the underlying input stream and then creates a long quantity, using the first byte read as the most significant byte. The method blocks until the eight bytes are read, the end of the stream is encountered, or an exception is thrown.
The short value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readShort()
This method reads a signed 16-bit short quantity from the stream. The method reads two bytes from the underlying input stream and then creates a short quantity, using the first byte read as the most significant byte. The method blocks until the two bytes are read, the end of the stream is encountered, or an exception is thrown.
The unsigned byte value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readUnsignedByte()
This method reads an unsigned 8-bit quantity from the stream. The method reads a byte from the underlying input stream and returns that byte, and blocks until the byte is read, the end of the stream is encountered, or an exception is thrown.
The unsigned short value read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
DataInput.readUnsignedShort()
This method reads an unsigned 16-bit quantity from the stream. The method reads two bytes from the underlying input stream and creates an unsigned short quantity, using the first byte read as the most significant byte. The method blocks until the two bytes are read, the end of the stream is encountered, or an exception is thrown.
The String read from the stream.
If the end of the file is encountered.
If any other kind of I/O error occurs.
If the bytes do not represent a valid UTF-8 encoding.
DataInput.readUTF()
This method reads a UTF-8 encoded string from the stream. See the description of the readUTF(DataInput) class method for more information.
The number of bytes to skip.
The actual number of skipped bytes.
If the end of the file is encountered.
If any other kind I/O error occurs.
DataInput.skipBytes()
This method skips over n bytes in the underlying input stream. The method blocks until all of the bytes are skipped, the end of the stream is encountered, or an exception is thrown.
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Method |
Inherited From |
Method |
Inherited From |
|---|---|---|---|
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available () |
FilterInputStream |
clone() |
Object |
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close() |
FilterInputStream |
equals(Object) |
Object |
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finalize() |
Object |
getClass() |
Object |
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hashCode() |
Object |
mark(int) |
FilterInputStream |
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markSupported() |
FilterInputStream |
notify() |
Object |
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notifyAll() |
Object |
read() |
FilterInputStream |
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reset() |
FilterInputStream |
skip(long) |
FilterInputStream |
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toString() |
Object |
wait() |
Object |
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wait(long) |
Object |
wait(long, int) |
Object |
DataOutputStream, Double, EOFException, FilterInputStream, Float, InputStream, IOException, String, UTFDataFormatException
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| DataInput |  |
DataOutput |
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