/*

 * Copyright (c) 2003, 2004, 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.util;

import java.io.IOException;

/**

 * The <tt>Formattable</tt> interface must be implemented by any class that

 * needs to perform custom formatting using the <tt>'s'</tt> conversion

 * specifier of {@link java.util.Formatter}.  This interface allows basic

 * control for formatting arbitrary objects.

 *

 * For example, the following class prints out different representations of a

 * stock's name depending on the flags and length constraints:

 *

 * {@code

 *   import java.nio.CharBuffer;

 *   import java.util.Formatter;

 *   import java.util.Formattable;

 *   import java.util.Locale;

 *   import static java.util.FormattableFlags.*;

 *

 *  ...

 *

 *   public class StockName implements Formattable {

 *       private String symbol, companyName, frenchCompanyName;

 *       public StockName(String symbol, String companyName,

 *                        String frenchCompanyName) {

 *           ...

 *       }

 *

 *       ...

 *

 *       public void formatTo(Formatter fmt, int f, int width, int precision) {

 *           StringBuilder sb = new StringBuilder();

 *

 *           // decide form of name

 *           String name = companyName;

 *           if (fmt.locale().equals(Locale.FRANCE))

 *               name = frenchCompanyName;

 *           boolean alternate = (f & ALTERNATE) == ALTERNATE;

 *           boolean usesymbol = alternate || (precision != -1 && precision < 10);

 *           String out = (usesymbol ? symbol : name);

 *

 *           // apply precision

 *           if (precision == -1 || out.length() < precision) {

 *               // write it all

 *               sb.append(out);

 *           } else {

 *               sb.append(out.substring(0, precision - 1)).append('*');

 *           }

 *

 *           // apply width and justification

 *           int len = sb.length();

 *           if (len < width)

 *               for (int i = 0; i < width - len; i++)

 *                   if ((f & LEFT_JUSTIFY) == LEFT_JUSTIFY)

 *                       sb.append(' ');

 *                   else

 *                       sb.insert(0, ' ');

 *

 *           fmt.format(sb.toString());

 *       }

 *

 *       public String toString() {

 *           return String.format("%s - %s", symbol, companyName);

 *       }

 *   }

 * }

 *

 * <p> When used in conjunction with the {@link java.util.Formatter}, the above

 * class produces the following output for various format strings.

 *

 * {@code

 *   Formatter fmt = new Formatter();

 *   StockName sn = new StockName("HUGE", "Huge Fruit, Inc.",

 *                                "Fruit Titanesque, Inc.");

 *   fmt.format("%s", sn);                   //   -> "Huge Fruit, Inc."

 *   fmt.format("%s", sn.toString());        //   -> "HUGE - Huge Fruit, Inc."

 *   fmt.format("%#s", sn);                  //   -> "HUGE"

 *   fmt.format("%-10.8s", sn);              //   -> "HUGE      "

 *   fmt.format("%.12s", sn);                //   -> "Huge Fruit,*"

 *   fmt.format(Locale.FRANCE, "%25s", sn);  //   -> "   Fruit Titanesque, Inc."

 * }

 *

 * <p> Formattables are not necessarily safe for multithreaded access.  Thread

 * safety is optional and may be enforced by classes that extend and implement

 * this interface.

 *

 * <p> Unless otherwise specified, passing a <tt>null</tt> argument to

 * any method in this interface will cause a {@link

 * NullPointerException} to be thrown.

 *

 * @since  1.5

 */

public interface Formattable {

    /**

     * Formats the object using the provided {@link Formatter formatter}.

     *

     * @param  formatter

     *         The {@link Formatter formatter}.  Implementing classes may call

     *         {@link Formatter#out() formatter.out()} or {@link

     *         Formatter#locale() formatter.locale()} to obtain the {@link

     *         Appendable} or {@link Locale} used by this

     *         <tt>formatter</tt> respectively.

     *

     * @param  flags

     *         The flags modify the output format.  The value is interpreted as

     *         a bitmask.  Any combination of the following flags may be set:

     *         {@link FormattableFlags#LEFT_JUSTIFY}, {@link

     *         FormattableFlags#UPPERCASE}, and {@link

     *         FormattableFlags#ALTERNATE}.  If no flags are set, the default

     *         formatting of the implementing class will apply.

     *

     * @param  width

     *         The minimum number of characters to be written to the output.

     *         If the length of the converted value is less than the

     *         <tt>width</tt> then the output will be padded by

     *         <tt>'&nbsp;&nbsp;'</tt> until the total number of characters

     *         equals width.  The padding is at the beginning by default.  If

     *         the {@link FormattableFlags#LEFT_JUSTIFY} flag is set then the

     *         padding will be at the end.  If <tt>width</tt> is <tt>-1</tt>

     *         then there is no minimum.

     *

     * @param  precision

     *         The maximum number of characters to be written to the output.

     *         The precision is applied before the width, thus the output will

     *         be truncated to <tt>precision</tt> characters even if the

     *         <tt>width</tt> is greater than the <tt>precision</tt>.  If

     *         <tt>precision</tt> is <tt>-1</tt> then there is no explicit

     *         limit on the number of characters.

     *

     * @throws  IllegalFormatException

     *          If any of the parameters are invalid.  For specification of all

     *          possible formatting errors, see the <a

     *          href="../util/Formatter.html#detail">Details</a> section of the

     *          formatter class specification.

     */

    void formatTo(Formatter formatter, int flags, int width, int precision);

}