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author | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
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committer | upstream source tree <ports@midipix.org> | 2015-03-15 20:14:05 -0400 |
commit | 554fd8c5195424bdbcabf5de30fdc183aba391bd (patch) | |
tree | 976dc5ab7fddf506dadce60ae936f43f58787092 /libjava/classpath/java/io/DataInput.java | |
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Diffstat (limited to 'libjava/classpath/java/io/DataInput.java')
-rw-r--r-- | libjava/classpath/java/io/DataInput.java | 456 |
1 files changed, 456 insertions, 0 deletions
diff --git a/libjava/classpath/java/io/DataInput.java b/libjava/classpath/java/io/DataInput.java new file mode 100644 index 000000000..a713319cf --- /dev/null +++ b/libjava/classpath/java/io/DataInput.java @@ -0,0 +1,456 @@ +/* DataInput.java -- Interface for reading data from a stream + Copyright (C) 1998, 1999, 2001, 2003, 2005 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA +02110-1301 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.io; + +/* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3 + * "The Java Language Specification", ISBN 0-201-63451-1 + * plus online API docs for JDK 1.2 beta from http://www.javasoft.com. + * Status: Believed complete and correct. */ + +/** + * This interface is implemented by classes that can data from streams + * into Java primitive types. + * + * @author Aaron M. Renn (arenn@urbanophile.com) + * @author Warren Levy (warrenl@cygnus.com) + */ +public interface DataInput +{ + + /** + * This method reads a Java boolean value from an input stream. It does + * so by reading a single byte of data. If that byte is zero, then the + * value returned is <code>false</code>. If the byte is non-zero, then + * the value returned is <code>true</code>. + * <p> + * This method can read a <code>boolean</code> written by an object + * implementing the <code>writeBoolean()</code> method in the + * <code>DataOutput</code> interface. + * + * @return The <code>boolean</code> value read + * + * @exception EOFException If end of file is reached before + * reading the boolean + * @exception IOException If any other error occurs + * + * @see DataOutput#writeBoolean + */ + boolean readBoolean() throws EOFException, IOException; + + /** + * This method reads a Java byte value from an input stream. The value + * is in the range of -128 to 127. + * <p> + * This method can read a <code>byte</code> written by an object + * implementing the + * <code>writeByte()</code> method in the <code>DataOutput</code> interface. + * <p> + * @return The <code>byte</code> value read + * + * @exception EOFException If end of file is reached before reading the byte + * @exception IOException If any other error occurs + * + * @see DataOutput#writeByte + */ + byte readByte() throws EOFException, IOException; + + /** + * This method reads 8 unsigned bits into a Java <code>int</code> value from + * the stream. The value returned is in the range of 0 to 255. + * <p> + * This method can read an unsigned byte written by an object + * implementing the + * <code>writeByte()</code> method in the <code>DataOutput</code> + * interface. + * + * @return The unsigned bytes value read as a Java <code>int</code>. + * + * @exception EOFException If end of file is reached before reading the value + * @exception IOException If any other error occurs + * + * @see DataOutput#writeByte + */ + int readUnsignedByte() throws EOFException, IOException; + + /** + * This method reads a Java <code>char</code> value from an input stream. + * It operates by reading two bytes from the stream and converting them to + * a single 16-bit Java <code>char</code>. The two bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> represent the + * first and second byte read from the stream respectively, they will be + * transformed to a <code>char</code> in the following manner: + * <p> + * <code>(char)((byte1 << 8) + byte2)</code> + * <p> + * This method can read a <code>char</code> written by an object implementing + * the + * <code>writeChar()</code> method in the <code>DataOutput</code> interface. + * + * @return The <code>char</code> value read + * + * @exception EOFException If end of file is reached before reading the char + * @exception IOException If any other error occurs + * + * @see DataOutput#writeChar + */ + char readChar() throws EOFException, IOException; + + /** + * This method reads a signed 16-bit value into a Java in from the stream. + * It operates by reading two bytes from the stream and converting them to + * a single 16-bit Java <code>short</code>. The two bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> represent the + * first and second byte read from the stream respectively, they will be + * transformed to a <code>short</code> in the following manner: + * <p> + * <code>(short)(((byte1 & 0xFF) << 8) + (byte2 & 0xFF))</code> + * <p> + * The value returned is in the range of -32768 to 32767. + * <p> + * This method can read a <code>short</code> written by an object + * implementing + * the <code>writeShort()</code> method in the <code>DataOutput</code> + * interface. + * + * @return The <code>short</code> value read + * + * @exception EOFException If end of file is reached before reading the value + * @exception IOException If any other error occurs + * + * @see DataOutput#writeShort + */ + short readShort() throws EOFException, IOException; + + /** + * This method reads 16 unsigned bits into a Java int value from the stream. + * It operates by reading two bytes from the stream and converting them to + * a single Java <code>int</code>. The two bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> represent the + * first and second byte read from the stream respectively, they will be + * transformed to an <code>int</code> in the following manner: + * <p> + * <code>(int)(((byte1 0xFF) << 8) + (byte2 & 0xFF))</code> + * <p> + * The value returned is in the range of 0 to 65535. + * <p> + * This method can read an unsigned short written by an object implementing + * the <code>writeShort()</code> method in the + * <code>DataOutput</code> + * interface. + * + * @return The unsigned short value read as a Java <code>int</code>. + * + * @exception EOFException If end of file is reached before reading + * the value + * @exception IOException If any other error occurs + * + * @see DataOutput#writeShort + */ + int readUnsignedShort() throws EOFException, IOException; + + /** + * This method reads a Java <code>int</code> value from an input stream + * It operates by reading four bytes from the stream and converting them to + * a single Java <code>int</code>. The bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> through <code>byte4</code> represent + * the first four bytes read from the stream, they will be + * transformed to an <code>int</code> in the following manner: + * <p> + * <code>(int)(((byte1 & 0xFF) << 24) + ((byte2 & 0xFF) << 16) + + * ((byte3 & 0xFF)<< 8) + (byte4 & 0xFF)))</code> + * <p> + * The value returned is in the range of -2147483648 to 2147483647. + * <p> + * This method can read an <code>int</code> written by an object + * implementing the <code>writeInt()</code> method in the + * <code>DataOutput</code> interface. + * + * @return The <code>int</code> value read + * + * @exception EOFException If end of file is reached before reading the int + * @exception IOException If any other error occurs + * + * @see DataOutput#writeInt + */ + int readInt() throws EOFException, IOException; + + /** + * This method reads a Java <code>long</code> value from an input stream + * It operates by reading eight bytes from the stream and converting them to + * a single Java <code>long</code>. The bytes are stored most + * significant byte first (i.e., "big endian") regardless of the native + * host byte ordering. + * <p> + * As an example, if <code>byte1</code> through <code>byte8</code> represent + * the first eight bytes read from the stream, they will be + * transformed to an <code>long</code> in the following manner: + * <p> + * <code>(long)(((byte1 & 0xFF) << 56) + ((byte2 & 0xFF) << 48) + + * ((byte3 & 0xFF) << 40) + ((byte4 & 0xFF) << 32) + + * ((byte5 & 0xFF) << 24) + ((byte6 & 0xFF) << 16) + + * ((byte7 & 0xFF) << 8) + (byte8 & 0xFF))) + * </code> + * <p> + * The value returned is in the range of -9223372036854775808 to + * 9223372036854775807. + * <p> + * This method can read an <code>long</code> written by an object + * implementing the <code>writeLong()</code> method in the + * <code>DataOutput</code> interface. + * + * @return The <code>long</code> value read + * + * @exception EOFException If end of file is reached before reading the long + * @exception IOException If any other error occurs + * + * @see DataOutput#writeLong + */ + long readLong() throws EOFException, IOException; + + /** + * This method reads a Java float value from an input stream. It operates + * by first reading an <code>int</code> value from the stream by calling the + * <code>readInt()</code> method in this interface, then converts that + * <code>int</code> to a <code>float</code> using the + * <code>intBitsToFloat</code> method in the class + * <code>java.lang.Float</code>. + * <p> + * This method can read a <code>float</code> written by an object + * implementing + * the <code>writeFloat()</code> method in the <code>DataOutput</code> + * interface. + * + * @return The <code>float</code> value read + * + * @exception EOFException If end of file is reached before reading the + * float + * @exception IOException If any other error occurs + * + * @see DataOutput#writeFloat + * @see java.lang.Float#intBitsToFloat + */ + float readFloat() throws EOFException, IOException; + + /** + * This method reads a Java double value from an input stream. It operates + * by first reading a <code>long</code> value from the stream by calling the + * <code>readLong()</code> method in this interface, then converts that + * <code>long</code> to a <code>double</code> using the + * <code>longBitsToDouble</code> method in the class + * <code>java.lang.Double</code>. + * <p> + * This method can read a <code>double</code> written by an object + * implementing the <code>writeDouble()</code> method in the + * <code>DataOutput</code> interface. + * + * @return The <code>double</code> value read + * + * @exception EOFException If end of file is reached before reading the + * double + * @exception IOException If any other error occurs + * + * @see DataOutput#writeDouble + * @see java.lang.Double#longBitsToDouble + */ + double readDouble() throws EOFException, IOException; + + /** + * This method reads the next line of text data from an input stream. + * It operates by reading bytes and converting those bytes to + * <code>char</code> + * values by treating the byte read as the low eight bits of the + * <code>char</code> and using 0 as the high eight bits. Because of this, + * it does not support the full 16-bit Unicode character set. + * <P> + * The reading of bytes ends when either the end of file or a line terminator + * is encountered. The bytes read are then returned as a + * <code>String</code>. + * A line terminator is a byte sequence consisting of either + * <code>\r</code>, <code>\n</code> or <code>\r\n</code>. These termination + * charaters are discarded and are not returned as part of the string. + * A line is also terminated by an end of file condition. + * <p> + * + * @return The line read as a <code>String</code> + * + * @exception IOException If an error occurs + */ + String readLine() throws IOException; + + /** + * This method reads a <code>String</code> from an input stream that is + * encoded in a modified UTF-8 format. This format has a leading two byte + * sequence that contains the remaining number of bytes to read. + * This two byte + * sequence is read using the <code>readUnsignedShort()</code> method of this + * interface. + * + * After the number of remaining bytes have been determined, these bytes + * are read an transformed into <code>char</code> values. These + * <code>char</code> values are encoded in the stream using either a one, + * two, or three byte format. + * The particular format in use can be determined by examining the first + * byte read. + * <p> + * If the first byte has a high order bit of 0, then + * that character consists on only one byte. This character value consists + * of seven bits that are at positions 0 through 6 of the byte. As an + * example, if <code>byte1</code> is the byte read from the stream, it would + * be converted to a <code>char</code> like so: + * <p> + * <code>(char)byte1</code> + * <p> + * If the first byte has 110 as its high order bits, then the + * character consists of two bytes. The bits that make up the character + * value are in positions 0 through 4 of the first byte and bit positions + * 0 through 5 of the second byte. (The second byte should have + * 10 as its high order bits). These values are in most significant + * byte first (i.e., "big endian") order. + * <p> + * As an example, if <code>byte1</code> and <code>byte2</code> are the first + * two bytes read respectively, and the high order bits of them match the + * patterns which indicate a two byte character encoding, then they would be + * converted to a Java <code>char</code> like so: + * <p> + * <code>(char)(((byte1 & 0x1F) << 6) + (byte2 & 0x3F))</code> + * <p> + * If the first byte has a 1110 as its high order bits, then the + * character consists of three bytes. The bits that make up the character + * value are in positions 0 through 3 of the first byte and bit positions + * 0 through 5 of the other two bytes. (The second and third bytes should + * have 10 as their high order bits). These values are in most + * significant byte first (i.e., "big endian") order. + * <p> + * As an example, if <code>byte1</code>, <code>byte2</code>, and + * <code>byte3</code> are the three bytes read, and the high order bits of + * them match the patterns which indicate a three byte character encoding, + * then they would be converted to a Java <code>char</code> like so: + * + * <code> + * (char)(((byte1 & 0x0F) << 12) + ((byte2 & 0x3F) + (byte3 & 0x3F)) + * </code> + * + * Note that all characters are encoded in the method that requires the + * fewest number of bytes with the exception of the character with the + * value of <code>\<llll>u0000</code> which is encoded as two bytes. + * This is a modification of the UTF standard used to prevent C language + * style <code>NUL</code> values from appearing in the byte stream. + * <p> + * This method can read data that was written by an object implementing the + * <code>writeUTF()</code> method in <code>DataOutput</code>. + * + * @return The <code>String</code> read + * + * @exception EOFException If end of file is reached before reading the + * String + * @exception UTFDataFormatException If the data is not in UTF-8 format + * @exception IOException If any other error occurs + * + * @see DataOutput#writeUTF + */ + String readUTF() throws EOFException, UTFDataFormatException, IOException; + + /** + * This method reads raw bytes into the passed array until the array is + * full. Note that this method blocks until the data is available and + * throws an exception if there is not enough data left in the stream to + * fill the buffer. Note also that zero length buffers are permitted. + * In this case, the method will return immediately without reading any + * bytes from the stream. + * + * @param buf The buffer into which to read the data + * + * @exception EOFException If end of file is reached before filling the + * buffer + * @exception IOException If any other error occurs + */ + void readFully(byte[] buf) throws EOFException, IOException; + + /** + * This method reads raw bytes into the passed array <code>buf</code> + * starting + * <code>offset</code> bytes into the buffer. The number of bytes read + * will be + * exactly <code>len</code>. Note that this method blocks until the data is + * available and throws an exception if there is not enough data left in + * the stream to read <code>len</code> bytes. Note also that zero length + * buffers are permitted. In this case, the method will return immediately + * without reading any bytes from the stream. + * + * @param buf The buffer into which to read the data + * @param offset The offset into the buffer to start storing data + * @param len The number of bytes to read into the buffer + * + * @exception EOFException If end of file is reached before filling the + * buffer + * @exception IOException If any other error occurs + */ + void readFully(byte[] buf, int offset, int len) + throws EOFException, IOException; + + /** + * This method skips and discards the specified number of bytes in an + * input stream. Note that this method may skip less than the requested + * number of bytes. The actual number of bytes skipped is returned. + * No bytes are skipped if a negative number is passed to this method. + * + * @param numBytes The number of bytes to skip + * + * @return The number of bytes actually skipped, which will always be + * <code>numBytes</code> + * + * @exception EOFException If end of file is reached before all bytes can be + * skipped + * @exception IOException If any other error occurs + */ + int skipBytes(int numBytes) throws EOFException, IOException; + +} // interface DataInput |