/*
 * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 */

package java.lang;

import java.io.IOException;

/**
 * An object to which <tt>char</tt> sequences and values can be appended. The
 * <tt>Appendable</tt> interface must be implemented by any class whose
 * instances are intended to receive formatted output from a {@link
 * java.util.Formatter}.
 *
 * <p> The characters to be appended should be valid Unicode characters as
 * described in <a href="Character.html#unicode">Unicode Character
 * Representation</a>. Note that supplementary characters may be composed of
 * multiple 16-bit <tt>char</tt> values.
 *
 * <p> Appendables are not necessarily safe for multithreaded access. Thread
 * safety is the responsibility of classes that extend and implement this
 * interface.
 *
 * <p> Since this interface may be implemented by existing classes
 * with different styles of error handling there is no guarantee that
 * errors will be propagated to the invoker.
 *
 * @since 1.5
 */
public interface Appendable {

 /**
 * Appends the specified character sequence to this <tt>Appendable</tt>.
 *
 * <p> Depending on which class implements the character sequence
 * <tt>csq</tt>, the entire sequence may not be appended. For
 * instance, if <tt>csq</tt> is a {@link java.nio.CharBuffer} then
 * the subsequence to append is defined by the buffer's position and limit.
 *
 * @param csq
 * The character sequence to append. If <tt>csq</tt> is
 * <tt>null</tt>, then the four characters <tt>"null"</tt> are
 * appended to this Appendable.
 *
 * @return A reference to this <tt>Appendable</tt>
 *
 * @throws IOException
 * If an I/O error occurs
 */
 Appendable append(CharSequence csq) throws IOException;

 /**
 * Appends a subsequence of the specified character sequence to this
 * <tt>Appendable</tt>.
 *
 * <p> An invocation of this method of the form <tt>out.append(csq, start,
 * end)</tt> when <tt>csq</tt> is not <tt>null</tt>, behaves in
 * exactly the same way as the invocation
 *
 * <pre>
 * out.append(csq.subSequence(start, end)) </pre>
 *
 * @param csq
 * The character sequence from which a subsequence will be
 * appended. If <tt>csq</tt> is <tt>null</tt>, then characters
 * will be appended as if <tt>csq</tt> contained the four
 * characters <tt>"null"</tt>.
 *
 * @param start
 * The index of the first character in the subsequence
 *
 * @param end
 * The index of the character following the last character in the
 * subsequence
 *
 * @return A reference to this <tt>Appendable</tt>
 *
 * @throws IndexOutOfBoundsException
 * If <tt>start</tt> or <tt>end</tt> are negative, <tt>start</tt>
 * is greater than <tt>end</tt>, or <tt>end</tt> is greater than
 * <tt>csq.length()</tt>
 *
 * @throws IOException
 * If an I/O error occurs
 */
 Appendable append(CharSequence csq, int start, int end) throws IOException;

 /**
 * Appends the specified character to this <tt>Appendable</tt>.
 *
 * @param c
 * The character to append
 *
 * @return A reference to this <tt>Appendable</tt>
 *
 * @throws IOException
 * If an I/O error occurs
 */
 Appendable append(char c) throws IOException;
}