Class java.io.RandomAccessFile
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Class java.io.RandomAccessFile
java.lang.Object
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+----java.io.RandomAccessFile
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public class
RandomAccessFile
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extends Object
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implements DataOutput, DataInput
Random access files can be constructed from file descriptors, file
names, or file objects. This class provides a sense of security
by offering methods that allow specified mode accesses of
read-only or read-write to files.
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RandomAccessFile(String, String)
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Creates a RandomAccessFile with the specified system dependent
file name and the specified mode.
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RandomAccessFile(int)
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Creates a RandomAccessFile with the specified system dependent
file descriptor.
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RandomAccessFile(File, String)
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Creates a RandomAccessFile from a specified File object
and mode ("r" or "rw").
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close()
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Closes the file.
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getFilePointer()
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Returns the current location of the file pointer.
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length()
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Returns the length of the file.
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read()
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Reads a byte of data.
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read(byte[], int, int)
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Reads a sub array as a sequence of bytes.
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read(byte[])
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Reads data into an array of bytes.
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readBoolean()
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Reads a boolean.
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readByte()
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Reads a byte.
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readChar()
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Reads a 16 bit char.
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readDouble()
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Reads a 64 bit double.
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readFloat()
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Reads a 32 bit float.
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readFully(byte[])
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Reads bytes, blocking until all bytes are read.
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readFully(byte[], int, int)
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Reads bytes, blocking until all bytes are read.
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readInt()
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Reads a 32 bit int.
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readLine()
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Reads a line terminated by a '\n' or EOF.
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readLong()
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Reads a 64 bit long.
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readShort()
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Reads 16 bit short.
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readUTF()
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Reads a UTF formatted String.
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readUnsignedByte()
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Reads an unsigned 8 bit byte.
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readUnsignedShort()
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Reads 16 bit short.
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seek(long)
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Sets the file pointer to the specified absolute position.
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skipBytes(int)
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write(int)
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Writes a byte of data.
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write(byte[])
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Writes an array of bytes.
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write(byte[], int, int)
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Wrotes a sub array of bytes.
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writeBoolean(boolean)
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Writes a boolean.
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writeByte(int)
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Writes a byte.
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writeBytes(String)
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Writes a String as a sequence of bytes.
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writeChar(int)
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Writes a character.
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writeChars(String)
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Writes a String as a sequence of chars.
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writeDouble(double)
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writeFloat(float)
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writeInt(int)
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Writes an integer.
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writeLong(long)
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Writes a long.
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writeShort(int)
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Writes a short.
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writeUTF(String)
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Writes a String in UTF format.
RandomAccessFile
public RandomAccessFile(String name,
String mode) throws IOException
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Creates a RandomAccessFile with the specified system dependent
file name and the specified mode.
Mode "r" is for read-only and mode "rw" is for read+write.
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Parameters:
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name
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the system dependent file name
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mode
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the access mode
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Throws: IOException
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If an I/O error has occurred.
RandomAccessFile
public RandomAccessFile(int fd) throws IOException
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Creates a RandomAccessFile with the specified system dependent
file descriptor.
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Parameters:
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fd
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the system dependent file descriptor
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Throws: IOException
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If an I/O error has occurred.
RandomAccessFile
public RandomAccessFile(File file,
String mode) throws IOException
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Creates a RandomAccessFile from a specified File object
and mode ("r" or "rw").
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Parameters:
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file
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the file object
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mode
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the access mode
read
public int read() throws IOException
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Reads a byte of data. This method will block if no input is
available.
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Returns:
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the byte read, or -1 if the end of the
stream is reached.
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Throws: IOException
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If an I/O error has occurred.
read
public int read(byte b[],
int off,
int len) throws IOException
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Reads a sub array as a sequence of bytes.
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Parameters:
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b
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the data to be written
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off
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the start offset in the data
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len
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the number of bytes that are written
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Throws: IOException
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If an I/O error has occurred.
read
public int read(byte b[]) throws IOException
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Reads data into an array of bytes. This method blocks
until some input is available.
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Returns:
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the actual number of bytes read, -1 is
returned when the end of the stream is reached.
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Throws: IOException
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If an I/O error has occurred.
readFully
public final void readFully(byte b[]) throws IOException
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Reads bytes, blocking until all bytes are read.
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Parameters:
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b
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the buffer into which the data is read
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Returns:
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the actual number of bytes read, -1 is
returned when the end of the stream is reached.
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Throws: IOException
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If an I/O error has occurred.
readFully
public final void readFully(byte b[],
int off,
int len) throws IOException
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Reads bytes, blocking until all bytes are read.
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Parameters:
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b
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the buffer into which the data is read
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off
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the start offset of the data
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len
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the maximum number of bytes read
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Returns:
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the actual number of bytes read, -1 is
returned when the end of the stream is reached.
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Throws: IOException
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If an I/O error has occurred.
skipBytes
public int skipBytes(int n) throws IOException
write
public void write(int b) throws IOException
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Writes a byte of data. This method will block until the byte
is actually written.
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Parameters:
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b
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the byte to be written
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Throws: IOException
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If an I/O error has occurred.
write
public void write(byte b[]) throws IOException
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Writes an array of bytes. Will block until the bytes
are actually written.
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Parameters:
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b
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the data to be written
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Throws: IOException
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If an I/O error has occurred.
write
public void write(byte b[],
int off,
int len) throws IOException
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Wrotes a sub array of bytes.
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Parameters:
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b
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the data to be written
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off
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the start offset in the data
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len
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the number of bytes that are written
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Throws: IOException
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If an I/O error has occurred.
getFilePointer
public long getFilePointer() throws IOException
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Returns the current location of the file pointer.
seek
public void seek(long pos) throws IOException
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Sets the file pointer to the specified absolute position.
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Parameters:
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pos
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the absolute position
length
public long length() throws IOException
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Returns the length of the file.
close
public void close() throws IOException
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Closes the file.
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Throws: IOException
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If an I/O error has occurred.
readBoolean
public final boolean readBoolean() throws IOException
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Reads a boolean.
readByte
public final byte readByte() throws IOException
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Reads a byte.
readUnsignedByte
public final int readUnsignedByte() throws IOException
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Reads an unsigned 8 bit byte.
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Returns:
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the 8 bit byte read.
readShort
public final short readShort() throws IOException
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Reads 16 bit short.
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Returns:
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the read 16 bit short.
readUnsignedShort
public final int readUnsignedShort() throws IOException
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Reads 16 bit short.
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Returns:
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the read 16 bit short.
readChar
public final char readChar() throws IOException
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Reads a 16 bit char.
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Returns:
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the read 16 bit char.
readInt
public final int readInt() throws IOException
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Reads a 32 bit int.
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Returns:
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the read 32 bit integer.
readLong
public final long readLong() throws IOException
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Reads a 64 bit long.
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Returns:
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the read 64 bit long.
readFloat
public final float readFloat() throws IOException
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Reads a 32 bit float.
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Returns:
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the read 32 bit float.
readDouble
public final double readDouble() throws IOException
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Reads a 64 bit double.
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Returns:
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the read 64 bit double.
readLine
public final String readLine() throws IOException
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Reads a line terminated by a '\n' or EOF.
readUTF
public final String readUTF() throws IOException
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Reads a UTF formatted String.
writeBoolean
public final void writeBoolean(boolean v) throws IOException
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Writes a boolean.
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Parameters:
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v
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the boolean value
writeByte
public final void writeByte(int v) throws IOException
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Writes a byte.
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Parameters:
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v
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the byte
writeShort
public final void writeShort(int v) throws IOException
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Writes a short.
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Parameters:
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v
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the short
writeChar
public final void writeChar(int v) throws IOException
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Writes a character.
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Parameters:
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v
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the char
writeInt
public final void writeInt(int v) throws IOException
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Writes an integer.
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Parameters:
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v
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the integer
writeLong
public final void writeLong(long v) throws IOException
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Writes a long.
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Parameters:
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v
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the long
writeFloat
public final void writeFloat(float v) throws IOException
writeDouble
public final void writeDouble(double v) throws IOException
writeBytes
public final void writeBytes(String s) throws IOException
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Writes a String as a sequence of bytes.
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Parameters:
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s
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the String
writeChars
public final void writeChars(String s) throws IOException
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Writes a String as a sequence of chars.
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Parameters:
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s
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the String
writeUTF
public final void writeUTF(String str) throws IOException
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Writes a String in UTF format.
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Parameters:
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str
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the String
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