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| 1 | /* | ||
| 2 | * Copyright (c) 2003, 2004, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.util; | ||
| 27 | |||
| 28 | import java.io.IOException; | ||
| 29 | |||
| 30 | /** | ||
| 31 | * The <tt>Formattable</tt> interface must be implemented by any class that | ||
| 32 | * needs to perform custom formatting using the <tt>'s'</tt> conversion | ||
| 33 | * specifier of {@link java.util.Formatter}. This interface allows basic | ||
| 34 | * control for formatting arbitrary objects. | ||
| 35 | * | ||
| 36 | * For example, the following class prints out different representations of a | ||
| 37 | * stock's name depending on the flags and length constraints: | ||
| 38 | * | ||
| 39 | * <blockquote><pre> | ||
| 40 | * import java.nio.CharBuffer; | ||
| 41 | * import java.util.Formatter; | ||
| 42 | * import java.util.Formattable; | ||
| 43 | * import java.util.Locale; | ||
| 44 | * import static java.util.FormattableFlags.*; | ||
| 45 | * | ||
| 46 | * ... | ||
| 47 | * | ||
| 48 | * public class StockName implements Formattable { | ||
| 49 | * private String symbol, companyName, frenchCompanyName; | ||
| 50 | * public StockName(String symbol, String companyName, | ||
| 51 | * String frenchCompanyName) { | ||
| 52 | * ... | ||
| 53 | * } | ||
| 54 | * | ||
| 55 | * ... | ||
| 56 | * | ||
| 57 | * public void formatTo(Formatter fmt, int f, int width, int precision) { | ||
| 58 | * StringBuilder sb = new StringBuilder(); | ||
| 59 | * | ||
| 60 | * // decide form of name | ||
| 61 | * String name = companyName; | ||
| 62 | * if (fmt.locale().equals(Locale.FRANCE)) | ||
| 63 | * name = frenchCompanyName; | ||
| 64 | * boolean alternate = (f & ALTERNATE) == ALTERNATE; | ||
| 65 | * boolean usesymbol = alternate || (precision != -1 && precision < 10); | ||
| 66 | * String out = (usesymbol ? symbol : name); | ||
| 67 | * | ||
| 68 | * // apply precision | ||
| 69 | * if (precision == -1 || out.length() < precision) { | ||
| 70 | * // write it all | ||
| 71 | * sb.append(out); | ||
| 72 | * } else { | ||
| 73 | * sb.append(out.substring(0, precision - 1)).append('*'); | ||
| 74 | * } | ||
| 75 | * | ||
| 76 | * // apply width and justification | ||
| 77 | * int len = sb.length(); | ||
| 78 | * if (len < width) | ||
| 79 | * for (int i = 0; i < width - len; i++) | ||
| 80 | * if ((f & LEFT_JUSTIFY) == LEFT_JUSTIFY) | ||
| 81 | * sb.append(' '); | ||
| 82 | * else | ||
| 83 | * sb.insert(0, ' '); | ||
| 84 | * | ||
| 85 | * fmt.format(sb.toString()); | ||
| 86 | * } | ||
| 87 | * | ||
| 88 | * public String toString() { | ||
| 89 | * return String.format("%s - %s", symbol, companyName); | ||
| 90 | * } | ||
| 91 | * } | ||
| 92 | * </pre></blockquote> | ||
| 93 | * | ||
| 94 | * <p> When used in conjunction with the {@link java.util.Formatter}, the above | ||
| 95 | * class produces the following output for various format strings. | ||
| 96 | * | ||
| 97 | * <blockquote><pre> | ||
| 98 | * Formatter fmt = new Formatter(); | ||
| 99 | * StockName sn = new StockName("HUGE", "Huge Fruit, Inc.", | ||
| 100 | * "Fruit Titanesque, Inc."); | ||
| 101 | * fmt.format("%s", sn); // -> "Huge Fruit, Inc." | ||
| 102 | * fmt.format("%s", sn.toString()); // -> "HUGE - Huge Fruit, Inc." | ||
| 103 | * fmt.format("%#s", sn); // -> "HUGE" | ||
| 104 | * fmt.format("%-10.8s", sn); // -> "HUGE " | ||
| 105 | * fmt.format("%.12s", sn); // -> "Huge Fruit,*" | ||
| 106 | * fmt.format(Locale.FRANCE, "%25s", sn); // -> " Fruit Titanesque, Inc." | ||
| 107 | * </pre></blockquote> | ||
| 108 | * | ||
| 109 | * <p> Formattables are not necessarily safe for multithreaded access. Thread | ||
| 110 | * safety is optional and may be enforced by classes that extend and implement | ||
| 111 | * this interface. | ||
| 112 | * | ||
| 113 | * <p> Unless otherwise specified, passing a <tt>null</tt> argument to | ||
| 114 | * any method in this interface will cause a {@link | ||
| 115 | * NullPointerException} to be thrown. | ||
| 116 | * | ||
| 117 | * @since 1.5 | ||
| 118 | */ | ||
| 119 | public interface Formattable { | ||
| 120 | |||
| 121 | /** | ||
| 122 | * Formats the object using the provided {@link Formatter formatter}. | ||
| 123 | * | ||
| 124 | * @param formatter | ||
| 125 | * The {@link Formatter formatter}. Implementing classes may call | ||
| 126 | * {@link Formatter#out() formatter.out()} or {@link | ||
| 127 | * Formatter#locale() formatter.locale()} to obtain the {@link | ||
| 128 | * Appendable} or {@link Locale} used by this | ||
| 129 | * <tt>formatter</tt> respectively. | ||
| 130 | * | ||
| 131 | * @param flags | ||
| 132 | * The flags modify the output format. The value is interpreted as | ||
| 133 | * a bitmask. Any combination of the following flags may be set: | ||
| 134 | * {@link FormattableFlags#LEFT_JUSTIFY}, {@link | ||
| 135 | * FormattableFlags#UPPERCASE}, and {@link | ||
| 136 | * FormattableFlags#ALTERNATE}. If no flags are set, the default | ||
| 137 | * formatting of the implementing class will apply. | ||
| 138 | * | ||
| 139 | * @param width | ||
| 140 | * The minimum number of characters to be written to the output. | ||
| 141 | * If the length of the converted value is less than the | ||
| 142 | * <tt>width</tt> then the output will be padded by | ||
| 143 | * <tt>' '</tt> until the total number of characters | ||
| 144 | * equals width. The padding is at the beginning by default. If | ||
| 145 | * the {@link FormattableFlags#LEFT_JUSTIFY} flag is set then the | ||
| 146 | * padding will be at the end. If <tt>width</tt> is <tt>-1</tt> | ||
| 147 | * then there is no minimum. | ||
| 148 | * | ||
| 149 | * @param precision | ||
| 150 | * The maximum number of characters to be written to the output. | ||
| 151 | * The precision is applied before the width, thus the output will | ||
| 152 | * be truncated to <tt>precision</tt> characters even if the | ||
| 153 | * <tt>width</tt> is greater than the <tt>precision</tt>. If | ||
| 154 | * <tt>precision</tt> is <tt>-1</tt> then there is no explicit | ||
| 155 | * limit on the number of characters. | ||
| 156 | * | ||
| 157 | * @throws IllegalFormatException | ||
| 158 | * If any of the parameters are invalid. For specification of all | ||
| 159 | * possible formatting errors, see the <a | ||
| 160 | * href="../util/Formatter.html#detail">Details</a> section of the | ||
| 161 | * formatter class specification. | ||
| 162 | */ | ||
| 163 | void formatTo(Formatter formatter, int flags, int width, int precision); | ||
| 164 | } | ||