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 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.util;

import java.io.IOException;

/**
 * The {@code Formattable} interface must be implemented by any class that
 * needs to perform custom formatting using the {@code 's'} 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:
 *
 * <pre> {@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);
 * }
 * }
 * }</pre>
 *
 * <p> When used in conjunction with the {@link java.util.Formatter}, the above
 * class produces the following output for various format strings.
 *
 * <pre> {@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."
 * }</pre>
 *
 * <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 {@code null} 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
 * {@code formatter} 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
 * {@code width} then the output will be padded by
 * <code>'&nbsp;&nbsp;'</code> 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 {@code width} is {@code -1}
 * 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 {@code precision} characters even if the
 * {@code width} is greater than the {@code precision}. If
 * {@code precision} is {@code -1} 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);
}