public interface JNLPRandomAccessFile
extends java.io.DataInput, java.io.DataOutput
getFilePointer
method and set by the seek
method.
It is generally true of all the reading routines in this class that
if end-of-file is reached before the desired number of bytes has been
read, an EOFException
(which is a kind of
IOException
) is thrown. If any byte cannot be read for
any reason other than end-of-file, an IOException
other
than EOFException
is thrown. In particular, an
IOException
may be thrown if the stream has been closed.
Implementations are encouraged to enforce a maximum amount of data that may be written to a file.
Modifier and Type | Method and Description |
---|---|
void |
close()
Closes this random access file stream and releases any system
resources associated with the stream.
|
long |
getFilePointer()
Returns the current offset in this file.
|
long |
length()
Returns the length of this file.
|
int |
read()
Reads a byte of data from this file.
|
int |
read(byte[] b)
Reads up to
b.length bytes of data from this file
into an array of bytes. |
int |
read(byte[] b,
int off,
int len)
Reads up to
len bytes of data from this file into an
array of bytes. |
boolean |
readBoolean()
Reads a
boolean from this file. |
byte |
readByte()
Reads a signed eight-bit value from this file.
|
char |
readChar()
Reads a Unicode character from this file.
|
double |
readDouble()
Reads a
double from this file. |
float |
readFloat()
Reads a
float from this file. |
void |
readFully(byte[] b)
Reads
b.length bytes from this file into the byte
array, starting at the current file pointer. |
void |
readFully(byte[] b,
int off,
int len)
Reads exactly
len bytes from this file into the byte
array, starting at the current file pointer. |
int |
readInt()
Reads a signed 32-bit integer from this file.
|
java.lang.String |
readLine()
Reads the next line of text from this file.
|
long |
readLong()
Reads a signed 64-bit integer from this file.
|
short |
readShort()
Reads a signed 16-bit number from this file.
|
int |
readUnsignedByte()
Reads an unsigned eight-bit number from this file.
|
int |
readUnsignedShort()
Reads an unsigned 16-bit number from this file.
|
java.lang.String |
readUTF()
Reads in a string from this file.
|
void |
seek(long pos)
Sets the file-pointer offset, measured from the beginning of this
file, at which the next read or write occurs.
|
void |
setLength(long newLength)
Sets the length of this file.
|
int |
skipBytes(int n)
Attempts to skip over
n bytes of input discarding the
skipped bytes. |
void |
write(byte[] b)
Writes
b.length bytes from the specified byte array
to this file, starting at the current file pointer. |
void |
write(byte[] b,
int off,
int len)
Writes
len bytes from the specified byte array
starting at offset off to this file. |
void |
write(int b)
Writes the specified byte to this file.
|
void |
writeBoolean(boolean v)
Writes a
boolean to the file as a one-byte value. |
void |
writeByte(int v)
Writes a
byte to the file as a one-byte value. |
void |
writeBytes(java.lang.String s)
Writes the string to the file as a sequence of bytes.
|
void |
writeChar(int v)
Writes a
char to the file as a two-byte value, high
byte first. |
void |
writeChars(java.lang.String s)
Writes a string to the file as a sequence of characters.
|
void |
writeDouble(double v)
Converts the double argument to a
long using the
doubleToLongBits method in class Double ,
and then writes that long value to the file as an
eight-byte quantity, high byte first. |
void |
writeFloat(float v)
Converts the float argument to an
int using the
floatToIntBits method in class Float ,
and then writes that int value to the file as a
four-byte quantity, high byte first. |
void |
writeInt(int v)
Writes an
int to the file as four bytes, high byte first. |
void |
writeLong(long v)
Writes a
long to the file as eight bytes, high byte first. |
void |
writeShort(int v)
Writes a
short to the file as two bytes, high byte first. |
void |
writeUTF(java.lang.String str)
Writes a string to the file using UTF-8 encoding in a
machine-independent manner.
|
void close() throws java.io.IOException
java.io.IOException
- if an I/O error occurs.long length() throws java.io.IOException
java.io.IOException
- if an I/O error occurs.long getFilePointer() throws java.io.IOException
java.io.IOException
- if an I/O error occurs.int read() throws java.io.IOException
0x00-0x0ff
). This
method blocks if no input is yet available.
Although JNLPRandomAccessFile
is not a subclass of
InputStream
, this method behaves in exactly the same
way as the read method of
InputStream
.
-1
if the end of the
file has been reached.java.io.IOException
- if an I/O error occurs. Not thrown if
end-of-file has been reached.int read(byte[] b, int off, int len) throws java.io.IOException
len
bytes of data from this file into an
array of bytes. This method blocks until at least one byte of input
is available.
Although JNLPRandomAccessFile
is not a subclass of
InputStream
, this method behaves in the exactly the
same way as the read(byte[], int, int) method of
InputStream
.
b
- the buffer into which the data is read.off
- the start offset of the data.len
- the maximum number of bytes read.-1
if there is no more data because the end of
the file has been reached.java.io.IOException
- if an I/O error occurs.int read(byte[] b) throws java.io.IOException
b.length
bytes of data from this file
into an array of bytes. This method blocks until at least one byte
of input is available.
Although JNLPRandomAccessFile
is not a subclass of
InputStream
, this method behaves in the exactly the
same way as the read(byte[]) method of
InputStream
.
b
- the buffer into which the data is read.-1
if there is no more data because the end of
this file has been reached.java.io.IOException
- if an I/O error occurs.void readFully(byte[] b) throws java.io.IOException
b.length
bytes from this file into the byte
array, starting at the current file pointer. This method reads
repeatedly from the file until the requested number of bytes are
read. This method blocks until the requested number of bytes are
read, the end of the stream is detected, or an exception is thrown.readFully
in interface java.io.DataInput
b
- the buffer into which the data is read.java.io.EOFException
- if this file reaches the end before reading
all the bytes.java.io.IOException
- if an I/O error occurs.void readFully(byte[] b, int off, int len) throws java.io.IOException
len
bytes from this file into the byte
array, starting at the current file pointer. This method reads
repeatedly from the file until the requested number of bytes are
read. This method blocks until the requested number of bytes are
read, the end of the stream is detected, or an exception is thrown.readFully
in interface java.io.DataInput
b
- the buffer into which the data is read.off
- the start offset of the data.len
- the number of bytes to read.java.io.EOFException
- if this file reaches the end before reading
all the bytes.java.io.IOException
- if an I/O error occurs.int skipBytes(int n) throws java.io.IOException
n
bytes of input discarding the
skipped bytes.
This method may skip over some smaller number of bytes, possibly zero.
This may result from any of a number of conditions; reaching end of
file before n
bytes have been skipped is only one
possibility. This method never throws an EOFException
.
The actual number of bytes skipped is returned. If n
is negative, no bytes are skipped.
skipBytes
in interface java.io.DataInput
n
- the number of bytes to be skipped.java.io.IOException
- if an I/O error occurs.boolean readBoolean() throws java.io.IOException
boolean
from this file. This method reads a
single byte from the file, starting at the current file pointer.
A value of 0
represents
false
. Any other value represents true
.
This method blocks until the byte is read, the end of the stream
is detected, or an exception is thrown.readBoolean
in interface java.io.DataInput
boolean
value read.java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.byte readByte() throws java.io.IOException
b
, where
0 <= b <= 255
,
then the result is:
(byte)(b)
This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.
readByte
in interface java.io.DataInput
byte
.java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.int readUnsignedByte() throws java.io.IOException
This method blocks until the byte is read, the end of the stream is detected, or an exception is thrown.
readUnsignedByte
in interface java.io.DataInput
java.io.EOFException
- if this file has reached the end.java.io.IOException
- if an I/O error occurs.short readShort() throws java.io.IOException
b1
and b2
, where each of the two values is
between 0
and 255
, inclusive, then the
result is equal to:
(short)((b1 << 8) | b2)
This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.
readShort
in interface java.io.DataInput
java.io.EOFException
- if this file reaches the end before reading
two bytes.java.io.IOException
- if an I/O error occurs.int readUnsignedShort() throws java.io.IOException
b1
and b2
, where
0 <= b1, b2 <= 255
,
then the result is equal to:
(b1 << 8) | b2
This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.
readUnsignedShort
in interface java.io.DataInput
java.io.EOFException
- if this file reaches the end before reading
two bytes.java.io.IOException
- if an I/O error occurs.char readChar() throws java.io.IOException
b1
and b2
, where
0 <= b1, b2 <= 255
,
then the result is equal to:
(char)((b1 << 8) | b2)
This method blocks until the two bytes are read, the end of the stream is detected, or an exception is thrown.
readChar
in interface java.io.DataInput
java.io.EOFException
- if this file reaches the end before reading
two bytes.java.io.IOException
- if an I/O error occurs.int readInt() throws java.io.IOException
b1
,
b2
, b3
, and b4
, where
0 <= b1, b2, b3, b4 <= 255
,
then the result is equal to:
(b1 << 24) | (b2 << 16) + (b3 << 8) + b4
This method blocks until the four bytes are read, the end of the stream is detected, or an exception is thrown.
readInt
in interface java.io.DataInput
int
.java.io.EOFException
- if this file reaches the end before reading
four bytes.java.io.IOException
- if an I/O error occurs.long readLong() throws java.io.IOException
b1
, b2
, b3
,
b4
, b5
, b6
,
b7
, and b8,
where:
0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
then the result is equal to:
((long)b1 << 56) + ((long)b2 << 48) + ((long)b3 << 40) + ((long)b4 << 32) + ((long)b5 << 24) + ((long)b6 << 16) + ((long)b7 << 8) + b8
This method blocks until the eight bytes are read, the end of the stream is detected, or an exception is thrown.
readLong
in interface java.io.DataInput
long
.java.io.EOFException
- if this file reaches the end before reading
eight bytes.java.io.IOException
- if an I/O error occurs.float readFloat() throws java.io.IOException
float
from this file. This method reads an
int
value, starting at the current file pointer,
as if by the readInt
method
and then converts that int
to a float
using the intBitsToFloat
method in class
Float
.
This method blocks until the four bytes are read, the end of the stream is detected, or an exception is thrown.
readFloat
in interface java.io.DataInput
float
.java.io.EOFException
- if this file reaches the end before reading
four bytes.java.io.IOException
- if an I/O error occurs.readInt()
double readDouble() throws java.io.IOException
double
from this file. This method reads a
long
value, starting at the current file pointer,
as if by the readLong
method
and then converts that long
to a double
using the longBitsToDouble
method in
class Double
.
This method blocks until the eight bytes are read, the end of the stream is detected, or an exception is thrown.
readDouble
in interface java.io.DataInput
double
.java.io.EOFException
- if this file reaches the end before reading
eight bytes.java.io.IOException
- if an I/O error occurs.readLong()
java.lang.String readLine() throws java.io.IOException
A line of text is terminated by a carriage-return character
('\r'
), a newline character ('\n'
), a
carriage-return character immediately followed by a newline character,
or the end of the file. Line-terminating characters are discarded and
are not included as part of the string returned.
This method blocks until a newline character is read, a carriage return and the byte following it are read (to see if it is a newline), the end of the file is reached, or an exception is thrown.
readLine
in interface java.io.DataInput
java.io.IOException
- if an I/O error occurs.java.lang.String readUTF() throws java.io.IOException
The first two bytes are read, starting from the current file
pointer, as if by
readUnsignedShort
. This value gives the number of
following bytes that are in the encoded string, not
the length of the resulting string. The following bytes are then
interpreted as bytes encoding characters in the UTF-8 format
and are converted into characters.
This method blocks until all the bytes are read, the end of the stream is detected, or an exception is thrown.
readUTF
in interface java.io.DataInput
java.io.EOFException
- if this file reaches the end before
reading all the bytes.java.io.IOException
- if an I/O error occurs.java.io.UTFDataFormatException
- if the bytes do not represent
valid UTF-8 encoding of a Unicode string.readUnsignedShort()
void seek(long pos) throws java.io.IOException
pos
- the offset position, measured in bytes from the
beginning of the file, at which to set the file
pointer.java.io.IOException
- if pos
is less than
0
or if an I/O error occurs.void setLength(long newLength) throws java.io.IOException
If the present length of the file as returned by the
length
method is greater than the newLength
argument then the file will be truncated. In this case, if the file
offset as returned by the getFilePointer
method is greater
then newLength
then after this method returns the offset
will be equal to newLength
.
If the present length of the file as returned by the
length
method is smaller than the newLength
argument then the file will be extended. In this case, the contents of
the extended portion of the file are not defined.
newLength
- The desired length of the filejava.io.IOException
- If an I/O error occursvoid write(int b) throws java.io.IOException
write
in interface java.io.DataOutput
b
- the byte
to be written.java.io.IOException
- if an I/O error occurs.void write(byte[] b) throws java.io.IOException
b.length
bytes from the specified byte array
to this file, starting at the current file pointer.write
in interface java.io.DataOutput
b
- the data.java.io.IOException
- if an I/O error occurs.void write(byte[] b, int off, int len) throws java.io.IOException
len
bytes from the specified byte array
starting at offset off
to this file.write
in interface java.io.DataOutput
b
- the data.off
- the start offset in the data.len
- the number of bytes to write.java.io.IOException
- if an I/O error occurs.void writeBoolean(boolean v) throws java.io.IOException
boolean
to the file as a one-byte value. The
value true
is written out as the value
(byte)1
; the value false
is written out
as the value (byte)0
. The write starts at
the current position of the file pointer.writeBoolean
in interface java.io.DataOutput
v
- a boolean
value to be written.java.io.IOException
- if an I/O error occurs.void writeByte(int v) throws java.io.IOException
byte
to the file as a one-byte value. The
write starts at the current position of the file pointer.writeByte
in interface java.io.DataOutput
v
- a byte
value to be written.java.io.IOException
- if an I/O error occurs.void writeShort(int v) throws java.io.IOException
short
to the file as two bytes, high byte first.
The write starts at the current position of the file pointer.writeShort
in interface java.io.DataOutput
v
- a short
to be written.java.io.IOException
- if an I/O error occurs.void writeChar(int v) throws java.io.IOException
char
to the file as a two-byte value, high
byte first. The write starts at the current position of the
file pointer.writeChar
in interface java.io.DataOutput
v
- a char
value to be written.java.io.IOException
- if an I/O error occurs.void writeInt(int v) throws java.io.IOException
int
to the file as four bytes, high byte first.
The write starts at the current position of the file pointer.writeInt
in interface java.io.DataOutput
v
- an int
to be written.java.io.IOException
- if an I/O error occurs.void writeLong(long v) throws java.io.IOException
long
to the file as eight bytes, high byte first.
The write starts at the current position of the file pointer.writeLong
in interface java.io.DataOutput
v
- a long
to be written.java.io.IOException
- if an I/O error occurs.void writeFloat(float v) throws java.io.IOException
int
using the
floatToIntBits
method in class Float
,
and then writes that int
value to the file as a
four-byte quantity, high byte first. The write starts at the
current position of the file pointer.writeFloat
in interface java.io.DataOutput
v
- a float
value to be written.java.io.IOException
- if an I/O error occurs.void writeDouble(double v) throws java.io.IOException
long
using the
doubleToLongBits
method in class Double
,
and then writes that long
value to the file as an
eight-byte quantity, high byte first. The write starts at the current
position of the file pointer.writeDouble
in interface java.io.DataOutput
v
- a double
value to be written.java.io.IOException
- if an I/O error occurs.void writeBytes(java.lang.String s) throws java.io.IOException
writeBytes
in interface java.io.DataOutput
s
- a string of bytes to be written.java.io.IOException
- if an I/O error occurs.void writeChars(java.lang.String s) throws java.io.IOException
writeChar
method. The write starts at the current
position of the file pointer.writeChars
in interface java.io.DataOutput
s
- a String
value to be written.java.io.IOException
- if an I/O error occurs.writeChar(int)
void writeUTF(java.lang.String str) throws java.io.IOException
First, two bytes are written to the file, starting at the
current file pointer, as if by the
writeShort
method giving the number of bytes to
follow. This value is the number of bytes actually written out,
not the length of the string. Following the length, each character
of the string is output, in sequence, using the UTF-8 encoding
for each character.
writeUTF
in interface java.io.DataOutput
str
- a string to be written.java.io.IOException
- if an I/O error occurs.Copyright © 1998, 2015, Oracle and/or its affiliates. All rights reserved.