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package java.lang;

import java.io.IOException;


An object to which char sequences and values can be appended. The Appendable interface must be implemented by any class whose instances are intended to receive formatted output from a Formatter. 
 The characters to be appended should be valid Unicode characters as
described in Unicode Character
Representation. Note that supplementary characters may be composed of multiple 16-bit char values. 
 Appendables are not necessarily safe for multithreaded access.  Thread
safety is the responsibility of classes that extend and implement this
interface.

 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
/**
 * An object to which {@code char} sequences and values can be appended.  The
 * {@code Appendable} 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 {@code char} 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 Appendable. 
 Depending on which class implements the character sequence csq, the entire sequence may not be appended. For instance, if csq is a CharBuffer then the subsequence to append is defined by the buffer's position and limit. 
Params:
  • csq –  The character sequence to append. If csq is null, then the four characters "null" are appended to this Appendable.
Throws:
Returns: A reference to this Appendable
/**
     * Appends the specified character sequence to this {@code Appendable}.
     *
     * <p> Depending on which class implements the character sequence
     * {@code csq}, the entire sequence may not be appended.  For
     * instance, if {@code csq} 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 {@code csq} is
     *         {@code null}, then the four characters {@code "null"} are
     *         appended to this Appendable.
     *
     * @return  A reference to this {@code Appendable}
     *
     * @throws  IOException
     *          If an I/O error occurs
     */
    Appendable append(CharSequence csq) throws IOException;

    
Appends a subsequence of the specified character sequence to this Appendable. 
 An invocation of this method of the form out.append(csq, start, end) when csq is not null, behaves in exactly the same way as the invocation 
    out.append(csq.subSequence(start, end)) 


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

    
Appends the specified character to this Appendable. 
Params:
  • c – 
        The character to append
Throws:
Returns: A reference to this Appendable
/**
     * Appends the specified character to this {@code Appendable}.
     *
     * @param  c
     *         The character to append
     *
     * @return  A reference to this {@code Appendable}
     *
     * @throws  IOException
     *          If an I/O error occurs
     */
    Appendable append(char c) throws IOException;
}