* (byte)(b)
* </pre>
* <p>
* This method blocks until the byte is read, the end of the stream
* is detected, or an exception is thrown.
*
* @return the next byte of this file as a signed eight-bit
* {@code byte}.
* @exception EOFException if this file has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final byte readByte() throws IOException {
int ch = this.read();
if (ch < 0)
throw new EOFException();
return (byte)(ch);
}
/**
* Reads an unsigned eight-bit number from this file. This method reads
* a byte from this file, starting at the current file pointer,
* and returns that byte.
* <p>
* This method blocks until the byte is read, the end of the stream
* is detected, or an exception is thrown.
*
* @return the next byte of this file, interpreted as an unsigned
* eight-bit number.
* @exception EOFException if this file has reached the end.
* @exception IOException if an I/O error occurs.
*/
public final int readUnsignedByte() throws IOException {
int ch = this.read();
if (ch < 0)
throw new EOFException();
return ch;
}
/**
* Reads a signed 16-bit number from this file. The method reads two
* bytes from this file, starting at the current file pointer.
* If the two bytes read, in order, are
* {@code b1} and {@code b2}, where each of the two values is
* between {@code 0} and {@code 255}, inclusive, then the
* result is equal to:
* <blockquote> * (short)((b1 << 8) | b2)
* </pre>
* <p>
* This method blocks until the two bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next two bytes of this file, interpreted as a signed
* 16-bit number.
* @exception EOFException if this file reaches the end before reading
* two bytes.
* @exception IOException if an I/O error occurs.
*/
public final short readShort() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (short)((ch1 << 8) + (ch2 << 0));
}
/**
* Reads an unsigned 16-bit number from this file. This method reads
* two bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are
* {@code b1} and {@code b2}, where
* <code>0 <= b1, b2 <= 255,
* then the result is equal to:
* <blockquote> * (b1 << 8) | b2
* </pre>
* <p>
* This method blocks until the two bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next two bytes of this file, interpreted as an unsigned
* 16-bit integer.
* @exception EOFException if this file reaches the end before reading
* two bytes.
* @exception IOException if an I/O error occurs.
*/
public final int readUnsignedShort() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (ch1 << 8) + (ch2 << 0);
}
/**
* Reads a character from this file. This method reads two
* bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are
* {@code b1} and {@code b2}, where
* <code>0 <= b1, b2 <= 255,
* then the result is equal to:
* <blockquote> * (char)((b1 << 8) | b2)
* </pre>
* <p>
* This method blocks until the two bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next two bytes of this file, interpreted as a
* {@code char}.
* @exception EOFException if this file reaches the end before reading
* two bytes.
* @exception IOException if an I/O error occurs.
*/
public final char readChar() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
if ((ch1 | ch2) < 0)
throw new EOFException();
return (char)((ch1 << 8) + (ch2 << 0));
}
/**
* Reads a signed 32-bit integer from this file. This method reads 4
* bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are {@code b1},
* {@code b2}, {@code b3}, and {@code b4}, where
* <code>0 <= b1, b2, b3, b4 <= 255,
* then the result is equal to:
* <blockquote> * (b1 << 24) | (b2 << 16) + (b3 << 8) + b4
* </pre>
* <p>
* This method blocks until the four bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next four bytes of this file, interpreted as an
* {@code int}.
* @exception EOFException if this file reaches the end before reading
* four bytes.
* @exception IOException if an I/O error occurs.
*/
public final int readInt() throws IOException {
int ch1 = this.read();
int ch2 = this.read();
int ch3 = this.read();
int ch4 = this.read();
if ((ch1 | ch2 | ch3 | ch4) < 0)
throw new EOFException();
return ((ch1 << 24) + (ch2 << 16) + (ch3 << 8) + (ch4 << 0));
}
/**
* Reads a signed 64-bit integer from this file. This method reads eight
* bytes from the file, starting at the current file pointer.
* If the bytes read, in order, are
* {@code b1}, {@code b2}, {@code b3},
* {@code b4}, {@code b5}, {@code b6},
* {@code b7}, and {@code b8,} where:
* <blockquote> * 0 <= b1, b2, b3, b4, b5, b6, b7, b8 <=255,
* </pre>
* <p>
* then the result is equal to:
* <blockquote> * ((long)b1 << 56) + ((long)b2 << 48)
* + ((long)b3 << 40) + ((long)b4 << 32)
* + ((long)b5 << 24) + ((long)b6 << 16)
* + ((long)b7 << 8) + b8
* </pre>
* <p>
* This method blocks until the eight bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next eight bytes of this file, interpreted as a
* {@code long}.
* @exception EOFException if this file reaches the end before reading
* eight bytes.
* @exception IOException if an I/O error occurs.
*/
public final long readLong() throws IOException {
return ((long)(readInt()) << 32) + (readInt() & 0xFFFFFFFFL);
}
/**
* Reads a {@code float} from this file. This method reads an
* {@code int} value, starting at the current file pointer,
* as if by the {@code readInt} method
* and then converts that {@code int} to a {@code float}
* using the {@code intBitsToFloat} method in class
* {@code Float}.
* <p>
* This method blocks until the four bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next four bytes of this file, interpreted as a
* {@code float}.
* @exception EOFException if this file reaches the end before reading
* four bytes.
* @exception IOException if an I/O error occurs.
* @see java.io.RandomAccessFile#readInt()
* @see java.lang.Float#intBitsToFloat(int)
*/
public final float readFloat() throws IOException {
return Float.intBitsToFloat(readInt());
}
/**
* Reads a {@code double} from this file. This method reads a
* {@code long} value, starting at the current file pointer,
* as if by the {@code readLong} method
* and then converts that {@code long} to a {@code double}
* using the {@code longBitsToDouble} method in
* class {@code Double}.
* <p>
* This method blocks until the eight bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return the next eight bytes of this file, interpreted as a
* {@code double}.
* @exception EOFException if this file reaches the end before reading
* eight bytes.
* @exception IOException if an I/O error occurs.
* @see java.io.RandomAccessFile#readLong()
* @see java.lang.Double#longBitsToDouble(long)
*/
public final double readDouble() throws IOException {
return Double.longBitsToDouble(readLong());
}
/**
* Reads the next line of text from this file. This method successively
* reads bytes from the file, starting at the current file pointer,
* until it reaches a line terminator or the end
* of the file. Each byte is converted into a character by taking the
* byte's value for the lower eight bits of the character and setting the
* high eight bits of the character to zero. This method does not,
* therefore, support the full Unicode character set.
*
* <p> A line of text is terminated by a carriage-return character
* ({@code '\u005Cr'}), a newline character ({@code '\u005Cn'}), 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.
*
* <p> 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.
*
* @return the next line of text from this file, or null if end
* of file is encountered before even one byte is read.
* @exception IOException if an I/O error occurs.
*/
public final String readLine() throws IOException {
StringBuffer input = new StringBuffer();
int c = -1;
boolean eol = false;
while (!eol) {
switch (c = read()) {
case -1:
case '\n':
eol = true;
break;
case '\r':
eol = true;
long cur = getFilePointer();
if ((read()) != '\n') {
seek(cur);
}
break;
default:
input.append((char)c);
break;
}
}
if ((c == -1) && (input.length() == 0)) {
return null;
}
return input.toString();
}
/**
* Reads in a string from this file. The string has been encoded
* using a
* <a href="DataInput.html#modified-utf-8">modified UTF-8
* format.
* <p>
* The first two bytes are read, starting from the current file
* pointer, as if by
* {@code 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 modified UTF-8 format
* and are converted into characters.
* <p>
* This method blocks until all the bytes are read, the end of the
* stream is detected, or an exception is thrown.
*
* @return a Unicode string.
* @exception EOFException if this file reaches the end before
* reading all the bytes.
* @exception IOException if an I/O error occurs.
* @exception UTFDataFormatException if the bytes do not represent
* valid modified UTF-8 encoding of a Unicode string.
* @see java.io.RandomAccessFile#readUnsignedShort()
*/
public final String readUTF() throws IOException {
return DataInputStream.readUTF(this);
}
/**
* Writes a {@code boolean} to the file as a one-byte value. The
* value {@code true} is written out as the value
* {@code (byte)1}; the value {@code false} is written out
* as the value {@code (byte)0}. The write starts at
* the current position of the file pointer.
*
* @param v a {@code boolean} value to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeBoolean(boolean v) throws IOException {
write(v ? 1 : 0);
//written++;
}
/**
* Writes a {@code byte} to the file as a one-byte value. The
* write starts at the current position of the file pointer.
*
* @param v a {@code byte} value to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeByte(int v) throws IOException {
write(v);
//written++;
}
/**
* Writes a {@code short} to the file as two bytes, high byte first.
* The write starts at the current position of the file pointer.
*
* @param v a {@code short} to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeShort(int v) throws IOException {
write((v >>> 8) & 0xFF);
write((v >>> 0) & 0xFF);
//written += 2;
}
/**
* Writes a {@code char} to the file as a two-byte value, high
* byte first. The write starts at the current position of the
* file pointer.
*
* @param v a {@code char} value to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeChar(int v) throws IOException {
write((v >>> 8) & 0xFF);
write((v >>> 0) & 0xFF);
//written += 2;
}
/**
* Writes an {@code int} to the file as four bytes, high byte first.
* The write starts at the current position of the file pointer.
*
* @param v an {@code int} to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeInt(int v) throws IOException {
write((v >>> 24) & 0xFF);
write((v >>> 16) & 0xFF);
write((v >>> 8) & 0xFF);
write((v >>> 0) & 0xFF);
//written += 4;
}
/**
* Writes a {@code long} to the file as eight bytes, high byte first.
* The write starts at the current position of the file pointer.
*
* @param v a {@code long} to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeLong(long v) throws IOException {
write((int)(v >>> 56) & 0xFF);
write((int)(v >>> 48) & 0xFF);
write((int)(v >>> 40) & 0xFF);
write((int)(v >>> 32) & 0xFF);
write((int)(v >>> 24) & 0xFF);
write((int)(v >>> 16) & 0xFF);
write((int)(v >>> 8) & 0xFF);
write((int)(v >>> 0) & 0xFF);
//written += 8;
}
/**
* Converts the float argument to an {@code int} using the
* {@code floatToIntBits} method in class {@code Float},
* and then writes that {@code int} value to the file as a
* four-byte quantity, high byte first. The write starts at the
* current position of the file pointer.
*
* @param v a {@code float} value to be written.
* @exception IOException if an I/O error occurs.
* @see java.lang.Float#floatToIntBits(float)
*/
public final void writeFloat(float v) throws IOException {
writeInt(Float.floatToIntBits(v));
}
/**
* Converts the double argument to a {@code long} using the
* {@code doubleToLongBits} method in class {@code Double},
* and then writes that {@code long} value to the file as an
* eight-byte quantity, high byte first. The write starts at the current
* position of the file pointer.
*
* @param v a {@code double} value to be written.
* @exception IOException if an I/O error occurs.
* @see java.lang.Double#doubleToLongBits(double)
*/
public final void writeDouble(double v) throws IOException {
writeLong(Double.doubleToLongBits(v));
}
/**
* Writes the string to the file as a sequence of bytes. Each
* character in the string is written out, in sequence, by discarding
* its high eight bits. The write starts at the current position of
* the file pointer.
*
* @param s a string of bytes to be written.
* @exception IOException if an I/O error occurs.
*/
@SuppressWarnings("deprecation")
public final void writeBytes(String s) throws IOException {
int len = s.length();
byte[] b = new byte[len];
s.getBytes(0, len, b, 0);
writeBytes(b, 0, len);
}
/**
* Writes a string to the file as a sequence of characters. Each
* character is written to the data output stream as if by the
* {@code writeChar} method. The write starts at the current
* position of the file pointer.
*
* @param s a {@code String} value to be written.
* @exception IOException if an I/O error occurs.
* @see java.io.RandomAccessFile#writeChar(int)
*/
public final void writeChars(String s) throws IOException {
int clen = s.length();
int blen = 2*clen;
byte[] b = new byte[blen];
char[] c = new char[clen];
s.getChars(0, clen, c, 0);
for (int i = 0, j = 0; i < clen; i++) {
b[j++] = (byte)(c[i] >>> 8);
b[j++] = (byte)(c[i] >>> 0);
}
writeBytes(b, 0, blen);
}
/**
* Writes a string to the file using
* <a href="DataInput.html#modified-utf-8">modified UTF-8
* encoding in a machine-independent manner.
* <p>
* First, two bytes are written to the file, starting at the
* current file pointer, as if by the
* {@code 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 modified UTF-8 encoding
* for each character.
*
* @param str a string to be written.
* @exception IOException if an I/O error occurs.
*/
public final void writeUTF(String str) throws IOException {
DataOutputStream.writeUTF(str, this);
}
private static native void initIDs();
private native void close0() throws IOException;
static {
initIDs();
}
}
Other Java examples (source code examples)
Here is a short list of links related to this Java RandomAccessFile.java source code file:
The search page
Other Java source code examples at this package level
Click here to learn more about this project
Java example source code file (RandomAccessFile.java)
The RandomAccessFile.java Java example source code/*
* Copyright (c) 1994, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.io;
import java.nio.channels.FileChannel;
import sun.nio.ch.FileChannelImpl;
/**
* Instances of this class support both reading and writing to a
* random access file. A random access file behaves like a large
* array of bytes stored in the file system. There is a kind of cursor,
* or index into the implied array, called the <em>file pointer;
* input operations read bytes starting at the file pointer and advance
* the file pointer past the bytes read. If the random access file is
* created in read/write mode, then output operations are also available;
* output operations write bytes starting at the file pointer and advance
* the file pointer past the bytes written. Output operations that write
* past the current end of the implied array cause the array to be
* extended. The file pointer can be read by the
* {@code getFilePointer} method and set by the {@code seek}
* method.
* <p>
* 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 {@code EOFException} (which is a kind of
* {@code IOException}) is thrown. If any byte cannot be read for
* any reason other than end-of-file, an {@code IOException} other
* than {@code EOFException} is thrown. In particular, an
* {@code IOException} may be thrown if the stream has been closed.
*
* @author unascribed
* @since JDK1.0
*/
public class RandomAccessFile implements DataOutput, DataInput, Closeable {
private FileDescriptor fd;
private FileChannel channel = null;
private boolean rw;
private Object closeLock = new Object();
private volatile boolean closed = false;
private static final int O_RDONLY = 1;
private static final int O_RDWR = 2;
private static final int O_SYNC = 4;
private static final int O_DSYNC = 8;
/**
* Creates a random access file stream to read from, and optionally
* to write to, a file with the specified name. A new
* {@link FileDescriptor} object is created to represent the
* connection to the file.
*
* <p> The mode argument specifies the access mode with which the
* file is to be opened. The permitted values and their meanings are as
* specified for the <a
* href="#mode"><tt>RandomAccessFile(File,String) constructor.
*
* <p>
* If there is a security manager, its {@code checkRead} method
* is called with the {@code name} argument
* as its argument to see if read access to the file is allowed.
* If the mode allows writing, the security manager's
* {@code checkWrite} method
* is also called with the {@code name} argument
* as its argument to see if write access to the file is allowed.
*
* @param name the system-dependent filename
* @param mode the access <a href="#mode">mode
* @exception IllegalArgumentException if the mode argument is not equal
* to one of <tt>"r", "rw", "rws", or
* <tt>"rwd"
* @exception FileNotFoundException
* if the mode is <tt>"r" but the given string does not
* denote an existing regular file, or if the mode begins with
* <tt>"rw" but the given string does not denote an
* existing, writable regular file and a new regular file of
* that name cannot be created, or if some other error occurs
* while opening or creating the file
* @exception SecurityException if a security manager exists and its
* {@code checkRead} method denies read access to the file
* or the mode is "rw" and the security manager's
* {@code checkWrite} method denies write access to the file
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkRead(java.lang.String)
* @see java.lang.SecurityManager#checkWrite(java.lang.String)
* @revised 1.4
* @spec JSR-51
*/
public RandomAccessFile(String name, String mode)
throws FileNotFoundException
{
this(name != null ? new File(name) : null, mode);
}
/**
* Creates a random access file stream to read from, and optionally to
* write to, the file specified by the {@link File} argument. A new {@link
* FileDescriptor} object is created to represent this file connection.
*
* <p>The mode argument specifies the access mode
* in which the file is to be opened. The permitted values and their
* meanings are:
*
* <table summary="Access mode permitted values and meanings">
* <tr> | Value | Meaning | |
|---|---|---|---|
| "r" | |||
| "rw" | |||
| "rws" | |||
| "rwd" |
