253 lines
7.0 KiB
Java
253 lines
7.0 KiB
Java
/* Copyright (C) 1998, 1999 Cygnus Solutions
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This file is part of libgcj.
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This software is copyrighted work licensed under the terms of the
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Libgcj License. Please consult the file "LIBGCJ_LICENSE" for
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details. */
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package java.io;
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/**
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* @author Warren Levy <warrenl@cygnus.com>
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* @date October 20, 1998.
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*/
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/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
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* "The Java Language Specification", ISBN 0-201-63451-1
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* plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
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* Status: Believed complete and correct.
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*/
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public class DataInputStream extends FilterInputStream implements DataInput
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{
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public DataInputStream(InputStream in)
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{
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super(in);
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}
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public final int read(byte[] b) throws IOException
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{
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return super.read(b, 0, b.length);
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}
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public final int read(byte[] b, int off, int len) throws IOException
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{
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if (off < 0 || len < 0 || off + len > b.length)
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throw new ArrayIndexOutOfBoundsException();
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return super.read(b, off, len);
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}
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public final boolean readBoolean() throws IOException
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{
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return (readByte() != 0);
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}
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public final byte readByte() throws IOException
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{
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int i = read();
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if (i < 0)
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throw new EOFException();
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return (byte) i;
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}
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public final char readChar() throws IOException
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{
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return (char) ((readByte() << 8) | readUnsignedByte());
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}
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public final double readDouble() throws IOException
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{
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return Double.longBitsToDouble(readLong());
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}
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public final float readFloat() throws IOException
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{
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return Float.intBitsToFloat(readInt());
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}
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public final void readFully(byte[] b) throws IOException
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{
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readFully(b, 0, b.length);
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}
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public final void readFully(byte[] b, int off, int len) throws IOException
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{
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if (off < 0 || len < 0 || off + len > b.length)
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throw new ArrayIndexOutOfBoundsException();
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while (len > 0)
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{
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// super.read will block until some data is available.
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int numread = super.read(b, off, len);
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if (numread < 0)
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throw new EOFException();
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len -= numread;
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off += numread;
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}
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}
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public final int readInt() throws IOException
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{
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int retval = 0;
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for (int i = 0; i < 4; i++)
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retval |= readUnsignedByte() << (24 - i * 8);
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return retval;
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}
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// Deprecated as of JDK 1.1
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public final String readLine() throws IOException
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{
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StringBuffer strb = new StringBuffer();
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while (true)
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{
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int c = read();
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if (c < 0) // got an EOF
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return strb.length() > 0 ? strb.toString() : null;
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char ch = (char) c;
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if ((ch &= 0xFF) == '\n')
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break;
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if (ch == '\r')
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{
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// FIXME: The following code tries to adjust the stream back one
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// character if the next char read is '\n'. As a last resort,
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// it tries to mark the position before reading but the bottom
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// line is that it is possible that this method will not properly
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// deal with a '\r' '\n' combination thus not fulfilling the
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// DataInput contract for readLine. It's not a particularly
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// safe approach threadwise since it is unsynchronized and
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// since it might mark an input stream behind the users back.
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// Along the same vein it could try the same thing for
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// ByteArrayInputStream and PushbackInputStream, but that is
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// probably overkill since this is deprecated & BufferedInputStream
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// is the most likely type of input stream.
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//
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// The alternative is to somehow push back the next byte if it
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// isn't a '\n' or to have the reading methods of this class
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// keep track of whether the last byte read was '\r' by readLine
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// and then skip the very next byte if it is '\n'. Either way,
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// this would increase the complexity of the non-deprecated methods
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// and since it is undesirable to make non-deprecated methods
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// less efficient, the following seems like the most reasonable
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// approach.
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if (in instanceof BufferedInputStream && (read() & 0xFF) != '\n')
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{
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BufferedInputStream bin = (BufferedInputStream) in;
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if (bin.pos > 0)
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bin.pos--;
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}
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else if (markSupported())
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{
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mark(1);
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if ((read() & 0xFF) != '\n')
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reset();
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}
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break;
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}
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strb.append(ch);
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}
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return strb.length() > 0 ? strb.toString() : "";
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}
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public final long readLong() throws IOException
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{
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long retval = 0L;
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for (int i = 0; i < 8; i++)
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retval |= (long) readUnsignedByte() << (56 - i * 8);
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return retval;
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}
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public final short readShort() throws IOException
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{
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return (short) ((readByte() << 8) | readUnsignedByte());
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}
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public final int readUnsignedByte() throws IOException
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{
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int i = read();
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if (i < 0)
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throw new EOFException();
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return (i & 0xFF);
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}
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public final int readUnsignedShort() throws IOException
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{
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return (readUnsignedByte() << 8) | readUnsignedByte();
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}
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public final String readUTF() throws IOException
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{
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return readUTF(this);
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}
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public final static String readUTF(DataInput in) throws IOException
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{
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final int UTFlen = in.readUnsignedShort();
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byte[] buf = new byte[UTFlen];
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StringBuffer strbuf = new StringBuffer();
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// This blocks until the entire string is available rather than
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// doing partial processing on the bytes that are available and then
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// blocking. An advantage of the latter is that Exceptions
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// could be thrown earlier. The former is a bit cleaner.
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in.readFully(buf, 0, UTFlen);
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for (int i = 0; i < UTFlen; )
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{
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if ((buf[i] & 0x80) == 0) // bit pattern 0xxxxxxx
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strbuf.append((char) (buf[i++] & 0xFF));
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else if ((buf[i] & 0xE0) == 0xC0) // bit pattern 110xxxxx
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{
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if (i + 1 >= UTFlen || (buf[i+1] & 0xC0) != 0x80)
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throw new UTFDataFormatException();
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strbuf.append((char) (((buf[i++] & 0x1F) << 6) |
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(buf[i++] & 0x3F)));
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}
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else if ((buf[i] & 0xF0) == 0xE0) // bit pattern 1110xxxx
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{
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if (i + 2 >= UTFlen ||
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(buf[i+1] & 0xC0) != 0x80 || (buf[i+2] & 0xC0) != 0x80)
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throw new UTFDataFormatException();
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strbuf.append((char) (((buf[i++] & 0x0F) << 12) |
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((buf[i++] & 0x3F) << 6) |
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(buf[i++] & 0x3F)));
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}
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else // must be ((buf[i] & 0xF0) == 0xF0 || (buf[i] & 0xC0) == 0x80)
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throw new UTFDataFormatException(); // bit patterns 1111xxxx or
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// 10xxxxxx
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}
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return strbuf.toString();
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}
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public final int skipBytes(int n) throws IOException
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{
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// The contract in the Java Lang. Spec. says that this never
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// throws an EOFException and infers that it doesn't block (since
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// it may skip less than the requested number of bytes).
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// BUT, the JCL book specifically says that this method blocks
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// and can throw an EOFException. Finally, the Java 1.2 online
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// doc simply refers to the general contract. As such, we will
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// stick to the contract and assume for now that the JCL book
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// is incorrect.
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// Since we're only skipping at most an int number of bytes, the cast
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// of return value to an int is fine.
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if (n > 0)
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{
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n = Math.min(n, available());
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return (int) super.skip((long) n);
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}
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return 0;
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}
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}
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