| /* |
| * Copyright (c) 2003, 2013, 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>' '</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); |
| } |
