1 | /*
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2 | * Licensed to the Apache Software Foundation (ASF) under one or more
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3 | * contributor license agreements. See the NOTICE file distributed with
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4 | * this work for additional information regarding copyright ownership.
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5 | * The ASF licenses this file to You under the Apache License, Version 2.0
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6 | * (the "License"); you may not use this file except in compliance with
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7 | * the License. You may obtain a copy of the License at
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8 | *
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9 | * http://www.apache.org/licenses/LICENSE-2.0
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10 | *
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11 | * Unless required by applicable law or agreed to in writing, software
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12 | * distributed under the License is distributed on an "AS IS" BASIS,
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13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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14 | * See the License for the specific language governing permissions and
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15 | * limitations under the License.
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16 | */
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17 | package agents.org.apache.commons.lang;
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18 |
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19 | import java.util.Random;
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20 | /**
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21 | * <p>Operations for random <code>String</code>s.</p>
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22 | * <p>Currently <em>private high surrogate</em> characters are ignored.
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23 | * These are unicode characters that fall between the values 56192 (db80)
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24 | * and 56319 (dbff) as we don't know how to handle them.
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25 | * High and low surrogates are correctly dealt with - that is if a
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26 | * high surrogate is randomly chosen, 55296 (d800) to 56191 (db7f)
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27 | * then it is followed by a low surrogate. If a low surrogate is chosen,
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28 | * 56320 (dc00) to 57343 (dfff) then it is placed after a randomly
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29 | * chosen high surrogate. </p>
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30 | *
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31 | * <p>#ThreadSafe#</p>
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32 | * @author Apache Software Foundation
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33 | * @author <a href="mailto:steven@caswell.name">Steven Caswell</a>
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34 | * @author Gary Gregory
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35 | * @author Phil Steitz
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36 | * @since 1.0
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37 | * @version $Id: RandomStringUtils.java 1056988 2011-01-09 17:58:53Z niallp $
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38 | */
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39 | public class RandomStringUtils {
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40 |
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41 | /**
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42 | * <p>Random object used by random method. This has to be not local
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43 | * to the random method so as to not return the same value in the
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44 | * same millisecond.</p>
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45 | */
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46 | private static final Random RANDOM = new Random();
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47 |
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48 | /**
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49 | * <p><code>RandomStringUtils</code> instances should NOT be constructed in
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50 | * standard programming. Instead, the class should be used as
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51 | * <code>RandomStringUtils.random(5);</code>.</p>
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52 | *
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53 | * <p>This constructor is public to permit tools that require a JavaBean instance
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54 | * to operate.</p>
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55 | */
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56 | public RandomStringUtils() {
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57 | super();
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58 | }
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59 |
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60 | // Random
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61 | //-----------------------------------------------------------------------
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62 | /**
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63 | * <p>Creates a random string whose length is the number of characters
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64 | * specified.</p>
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65 | *
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66 | * <p>Characters will be chosen from the set of all characters.</p>
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67 | *
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68 | * @param count the length of random string to create
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69 | * @return the random string
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70 | */
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71 | public static String random(int count) {
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72 | return random(count, false, false);
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73 | }
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74 |
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75 | /**
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76 | * <p>Creates a random string whose length is the number of characters
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77 | * specified.</p>
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78 | *
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79 | * <p>Characters will be chosen from the set of characters whose
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80 | * ASCII value is between <code>32</code> and <code>126</code> (inclusive).</p>
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81 | *
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82 | * @param count the length of random string to create
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83 | * @return the random string
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84 | */
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85 | public static String randomAscii(int count) {
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86 | return random(count, 32, 127, false, false);
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87 | }
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88 |
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89 | /**
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90 | * <p>Creates a random string whose length is the number of characters
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91 | * specified.</p>
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92 | *
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93 | * <p>Characters will be chosen from the set of alphabetic
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94 | * characters.</p>
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95 | *
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96 | * @param count the length of random string to create
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97 | * @return the random string
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98 | */
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99 | public static String randomAlphabetic(int count) {
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100 | return random(count, true, false);
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101 | }
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102 |
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103 | /**
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104 | * <p>Creates a random string whose length is the number of characters
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105 | * specified.</p>
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106 | *
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107 | * <p>Characters will be chosen from the set of alpha-numeric
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108 | * characters.</p>
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109 | *
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110 | * @param count the length of random string to create
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111 | * @return the random string
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112 | */
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113 | public static String randomAlphanumeric(int count) {
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114 | return random(count, true, true);
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115 | }
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116 |
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117 | /**
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118 | * <p>Creates a random string whose length is the number of characters
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119 | * specified.</p>
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120 | *
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121 | * <p>Characters will be chosen from the set of numeric
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122 | * characters.</p>
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123 | *
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124 | * @param count the length of random string to create
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125 | * @return the random string
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126 | */
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127 | public static String randomNumeric(int count) {
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128 | return random(count, false, true);
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129 | }
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130 |
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131 | /**
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132 | * <p>Creates a random string whose length is the number of characters
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133 | * specified.</p>
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134 | *
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135 | * <p>Characters will be chosen from the set of alpha-numeric
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136 | * characters as indicated by the arguments.</p>
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137 | *
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138 | * @param count the length of random string to create
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139 | * @param letters if <code>true</code>, generated string will include
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140 | * alphabetic characters
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141 | * @param numbers if <code>true</code>, generated string will include
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142 | * numeric characters
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143 | * @return the random string
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144 | */
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145 | public static String random(int count, boolean letters, boolean numbers) {
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146 | return random(count, 0, 0, letters, numbers);
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147 | }
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148 |
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149 | /**
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150 | * <p>Creates a random string whose length is the number of characters
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151 | * specified.</p>
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152 | *
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153 | * <p>Characters will be chosen from the set of alpha-numeric
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154 | * characters as indicated by the arguments.</p>
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155 | *
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156 | * @param count the length of random string to create
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157 | * @param start the position in set of chars to start at
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158 | * @param end the position in set of chars to end before
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159 | * @param letters if <code>true</code>, generated string will include
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160 | * alphabetic characters
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161 | * @param numbers if <code>true</code>, generated string will include
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162 | * numeric characters
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163 | * @return the random string
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164 | */
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165 | public static String random(int count, int start, int end, boolean letters, boolean numbers) {
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166 | return random(count, start, end, letters, numbers, null, RANDOM);
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167 | }
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168 |
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169 | /**
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170 | * <p>Creates a random string based on a variety of options, using
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171 | * default source of randomness.</p>
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172 | *
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173 | * <p>This method has exactly the same semantics as
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174 | * {@link #random(int,int,int,boolean,boolean,char[],Random)}, but
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175 | * instead of using an externally supplied source of randomness, it uses
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176 | * the internal static {@link Random} instance.</p>
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177 | *
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178 | * @param count the length of random string to create
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179 | * @param start the position in set of chars to start at
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180 | * @param end the position in set of chars to end before
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181 | * @param letters only allow letters?
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182 | * @param numbers only allow numbers?
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183 | * @param chars the set of chars to choose randoms from.
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184 | * If <code>null</code>, then it will use the set of all chars.
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185 | * @return the random string
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186 | * @throws ArrayIndexOutOfBoundsException if there are not
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187 | * <code>(end - start) + 1</code> characters in the set array.
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188 | */
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189 | public static String random(int count, int start, int end, boolean letters, boolean numbers, char[] chars) {
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190 | return random(count, start, end, letters, numbers, chars, RANDOM);
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191 | }
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192 |
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193 | /**
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194 | * <p>Creates a random string based on a variety of options, using
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195 | * supplied source of randomness.</p>
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196 | *
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197 | * <p>If start and end are both <code>0</code>, start and end are set
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198 | * to <code>' '</code> and <code>'z'</code>, the ASCII printable
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199 | * characters, will be used, unless letters and numbers are both
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200 | * <code>false</code>, in which case, start and end are set to
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201 | * <code>0</code> and <code>Integer.MAX_VALUE</code>.
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202 | *
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203 | * <p>If set is not <code>null</code>, characters between start and
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204 | * end are chosen.</p>
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205 | *
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206 | * <p>This method accepts a user-supplied {@link Random}
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207 | * instance to use as a source of randomness. By seeding a single
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208 | * {@link Random} instance with a fixed seed and using it for each call,
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209 | * the same random sequence of strings can be generated repeatedly
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210 | * and predictably.</p>
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211 | *
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212 | * @param count the length of random string to create
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213 | * @param start the position in set of chars to start at
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214 | * @param end the position in set of chars to end before
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215 | * @param letters only allow letters?
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216 | * @param numbers only allow numbers?
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217 | * @param chars the set of chars to choose randoms from.
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218 | * If <code>null</code>, then it will use the set of all chars.
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219 | * @param random a source of randomness.
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220 | * @return the random string
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221 | * @throws ArrayIndexOutOfBoundsException if there are not
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222 | * <code>(end - start) + 1</code> characters in the set array.
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223 | * @throws IllegalArgumentException if <code>count</code> < 0.
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224 | * @since 2.0
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225 | */
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226 | public static String random(int count, int start, int end, boolean letters, boolean numbers,
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227 | char[] chars, Random random) {
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228 | if (count == 0) {
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229 | return "";
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230 | } else if (count < 0) {
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231 | throw new IllegalArgumentException("Requested random string length " + count + " is less than 0.");
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232 | }
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233 | if ((start == 0) && (end == 0)) {
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234 | end = 'z' + 1;
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235 | start = ' ';
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236 | if (!letters && !numbers) {
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237 | start = 0;
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238 | end = Integer.MAX_VALUE;
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239 | }
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240 | }
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241 |
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242 | char[] buffer = new char[count];
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243 | int gap = end - start;
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244 |
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245 | while (count-- != 0) {
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246 | char ch;
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247 | if (chars == null) {
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248 | ch = (char) (random.nextInt(gap) + start);
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249 | } else {
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250 | ch = chars[random.nextInt(gap) + start];
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251 | }
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252 | if ((letters && Character.isLetter(ch))
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253 | || (numbers && Character.isDigit(ch))
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254 | || (!letters && !numbers))
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255 | {
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256 | if(ch >= 56320 && ch <= 57343) {
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257 | if(count == 0) {
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258 | count++;
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259 | } else {
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260 | // low surrogate, insert high surrogate after putting it in
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261 | buffer[count] = ch;
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262 | count--;
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263 | buffer[count] = (char) (55296 + random.nextInt(128));
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264 | }
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265 | } else if(ch >= 55296 && ch <= 56191) {
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266 | if(count == 0) {
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267 | count++;
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268 | } else {
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269 | // high surrogate, insert low surrogate before putting it in
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270 | buffer[count] = (char) (56320 + random.nextInt(128));
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271 | count--;
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272 | buffer[count] = ch;
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273 | }
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274 | } else if(ch >= 56192 && ch <= 56319) {
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275 | // private high surrogate, no effing clue, so skip it
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276 | count++;
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277 | } else {
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278 | buffer[count] = ch;
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279 | }
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280 | } else {
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281 | count++;
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282 | }
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283 | }
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284 | return new String(buffer);
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285 | }
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286 |
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287 | /**
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288 | * <p>Creates a random string whose length is the number of characters
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289 | * specified.</p>
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290 | *
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291 | * <p>Characters will be chosen from the set of characters
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292 | * specified.</p>
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293 | *
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294 | * @param count the length of random string to create
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295 | * @param chars the String containing the set of characters to use,
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296 | * may be null
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297 | * @return the random string
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298 | * @throws IllegalArgumentException if <code>count</code> < 0.
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299 | */
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300 | public static String random(int count, String chars) {
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301 | if (chars == null) {
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302 | return random(count, 0, 0, false, false, null, RANDOM);
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303 | }
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304 | return random(count, chars.toCharArray());
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305 | }
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306 |
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307 | /**
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308 | * <p>Creates a random string whose length is the number of characters
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309 | * specified.</p>
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310 | *
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311 | * <p>Characters will be chosen from the set of characters specified.</p>
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312 | *
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313 | * @param count the length of random string to create
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314 | * @param chars the character array containing the set of characters to use,
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315 | * may be null
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316 | * @return the random string
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317 | * @throws IllegalArgumentException if <code>count</code> < 0.
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318 | */
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319 | public static String random(int count, char[] chars) {
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320 | if (chars == null) {
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321 | return random(count, 0, 0, false, false, null, RANDOM);
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322 | }
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323 | return random(count, 0, chars.length, false, false, chars, RANDOM);
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324 | }
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325 |
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326 | }
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