001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.lang3.text;
018
019 import static java.util.FormattableFlags.LEFT_JUSTIFY;
020
021 import java.util.Formattable;
022 import java.util.Formatter;
023
024 import org.apache.commons.lang3.ObjectUtils;
025 import org.apache.commons.lang3.StringUtils;
026 import org.apache.commons.lang3.Validate;
027
028 /**
029 * <p>Provides utilities for working with the {@code Formattable} interface.</p>
030 *
031 * <p>The {@link Formattable} interface provides basic control over formatting
032 * when using a {@code Formatter}. It is primarily concerned with numeric precision
033 * and padding, and is not designed to allow generalised alternate formats.</p>
034 *
035 * @since Lang 3.0
036 * @version $Id: FormattableUtils.java 1132390 2011-06-05 12:45:10Z sebb $
037 */
038 public class FormattableUtils {
039
040 /**
041 * A format that simply outputs the value as a string.
042 */
043 private static final String SIMPLEST_FORMAT = "%s";
044
045 /**
046 * <p>{@code FormattableUtils} instances should NOT be constructed in
047 * standard programming. Instead, the methods of the class should be invoked
048 * statically.</p>
049 *
050 * <p>This constructor is public to permit tools that require a JavaBean
051 * instance to operate.</p>
052 */
053 public FormattableUtils() {
054 super();
055 }
056
057 //-----------------------------------------------------------------------
058 /**
059 * Get the default formatted representation of the specified
060 * {@code Formattable}.
061 *
062 * @param formattable the instance to convert to a string, not null
063 * @return the resulting string, not null
064 */
065 public static String toString(Formattable formattable) {
066 return String.format(SIMPLEST_FORMAT, formattable);
067 }
068
069 /**
070 * Handles the common {@code Formattable} operations of truncate-pad-append,
071 * with no ellipsis on precision overflow, and padding width underflow with
072 * spaces.
073 *
074 * @param seq the string to handle, not null
075 * @param formatter the destination formatter, not null
076 * @param flags the flags for formatting, see {@code Formattable}
077 * @param width the width of the output, see {@code Formattable}
078 * @param precision the precision of the output, see {@code Formattable}
079 * @return the {@code formatter} instance, not null
080 */
081 public static Formatter append(CharSequence seq, Formatter formatter, int flags, int width,
082 int precision) {
083 return append(seq, formatter, flags, width, precision, ' ', null);
084 }
085
086 /**
087 * Handles the common {@link Formattable} operations of truncate-pad-append,
088 * with no ellipsis on precision overflow.
089 *
090 * @param seq the string to handle, not null
091 * @param formatter the destination formatter, not null
092 * @param flags the flags for formatting, see {@code Formattable}
093 * @param width the width of the output, see {@code Formattable}
094 * @param precision the precision of the output, see {@code Formattable}
095 * @param padChar the pad character to use
096 * @return the {@code formatter} instance, not null
097 */
098 public static Formatter append(CharSequence seq, Formatter formatter, int flags, int width,
099 int precision, char padChar) {
100 return append(seq, formatter, flags, width, precision, padChar, null);
101 }
102
103 /**
104 * Handles the common {@link Formattable} operations of truncate-pad-append,
105 * padding width underflow with spaces.
106 *
107 * @param seq the string to handle, not null
108 * @param formatter the destination formatter, not null
109 * @param flags the flags for formatting, see {@code Formattable}
110 * @param width the width of the output, see {@code Formattable}
111 * @param precision the precision of the output, see {@code Formattable}
112 * @param ellipsis the ellipsis to use when precision dictates truncation, null or
113 * empty causes a hard truncation
114 * @return the {@code formatter} instance, not null
115 */
116 public static Formatter append(CharSequence seq, Formatter formatter, int flags, int width,
117 int precision, CharSequence ellipsis) {
118 return append(seq, formatter, flags, width, precision, ' ', ellipsis);
119 }
120
121 /**
122 * Handles the common {@link Formattable} operations of truncate-pad-append.
123 *
124 * @param seq the string to handle, not null
125 * @param formatter the destination formatter, not null
126 * @param flags the flags for formatting, see {@code Formattable}
127 * @param width the width of the output, see {@code Formattable}
128 * @param precision the precision of the output, see {@code Formattable}
129 * @param padChar the pad character to use
130 * @param ellipsis the ellipsis to use when precision dictates truncation, null or
131 * empty causes a hard truncation
132 * @return the {@code formatter} instance, not null
133 */
134 public static Formatter append(CharSequence seq, Formatter formatter, int flags, int width,
135 int precision, char padChar, CharSequence ellipsis) {
136 Validate.isTrue(ellipsis == null || precision < 0 || ellipsis.length() <= precision,
137 "Specified ellipsis '%1$s' exceeds precision of %2$s", ellipsis, Integer.valueOf(precision));
138 StringBuilder buf = new StringBuilder(seq);
139 if (precision >= 0 && precision < seq.length()) {
140 CharSequence _ellipsis = ObjectUtils.defaultIfNull(ellipsis, StringUtils.EMPTY);
141 buf.replace(precision - _ellipsis.length(), seq.length(), _ellipsis.toString());
142 }
143 boolean leftJustify = (flags & LEFT_JUSTIFY) == LEFT_JUSTIFY;
144 for (int i = buf.length(); i < width; i++) {
145 buf.insert(leftJustify ? i : 0, padChar);
146 }
147 formatter.format(buf.toString());
148 return formatter;
149 }
150
151 }