Checks if a CharSequence is empty ("") or null.
132 | * 133 | *
134 | * StringUtils.isEmpty(null) = true
135 | * StringUtils.isEmpty("") = true
136 | * StringUtils.isEmpty(" ") = false
137 | * StringUtils.isEmpty("bob") = false
138 | * StringUtils.isEmpty(" bob ") = false
139 | *
140 | *
141 | * NOTE: This method changed in Lang version 2.0. 142 | * It no longer trims the CharSequence. 143 | * That functionality is available in isBlank().
144 | * 145 | * @param cs the CharSequence to check, may be null 146 | * @return {@code true} if the CharSequence is empty or null 147 | * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence) 148 | */ 149 | public static boolean isEmpty(final CharSequence cs) { 150 | return cs == null || cs.length() == 0; 151 | } 152 | 153 | /** 154 | * encodeHex and encodeHexString were copied from the Apache commons-codec 155 | * library. 156 | * https://github.com/apache/commons-codec/blob/master/src/main/java/org/apache/commons/codec/binary/Hex.java 157 | * 158 | */ 159 | /** 160 | * Used to build output as Hex 161 | */ 162 | private static final char[] DIGITS_LOWER = { 163 | '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 164 | 'e', 'f' 165 | }; 166 | 167 | /** 168 | * Used to build output as Hex 169 | */ 170 | private static final char[] DIGITS_UPPER = { 171 | '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 172 | 'E', 'F' 173 | }; 174 | 175 | /** 176 | * Converts an array of bytes into a String representing the hexadecimal 177 | * values of each byte in order. The returned String will be double the 178 | * length of the passed array, as it takes two characters to represent any 179 | * given byte. 180 | * 181 | * @param data a byte[] to convert to Hex characters 182 | * @return A String containing lower-case hexadecimal characters 183 | * @since 1.4 184 | */ 185 | public static String encodeHexString(final byte[] data) { 186 | return new String(encodeHex(data)); 187 | } 188 | 189 | /** 190 | * Converts an array of bytes into a String representing the hexadecimal 191 | * values of each byte in order. The returned String will be double the 192 | * length of the passed array, as it takes two characters to represent any 193 | * given byte. 194 | * 195 | * @param data a byte[] to convert to Hex characters 196 | * @param toLowerCase {@code true} converts to lowercase, {@code false} to 197 | * uppercase 198 | * @return A String containing lower-case hexadecimal characters 199 | * @since 1.11 200 | */ 201 | public static String encodeHexString(final byte[] data, final boolean toLowerCase) { 202 | return new String(encodeHex(data, toLowerCase)); 203 | } 204 | 205 | /** 206 | * Converts an array of bytes into an array of characters representing the 207 | * hexadecimal values of each byte in order. The returned array will be 208 | * double the length of the passed array, as it takes two characters to 209 | * represent any given byte. 210 | * 211 | * @param data a byte[] to convert to Hex characters 212 | * @return A char[] containing lower-case hexadecimal characters 213 | */ 214 | public static char[] encodeHex(final byte[] data) { 215 | return encodeHex(data, true); 216 | } 217 | 218 | /** 219 | * Converts an array of bytes into an array of characters representing the 220 | * hexadecimal values of each byte in order. The returned array will be 221 | * double the length of the passed array, as it takes two characters to 222 | * represent any given byte. 223 | * 224 | * @param data a byte[] to convert to Hex characters 225 | * @param toLowerCase {@code true} converts to lowercase, {@code false} to 226 | * uppercase 227 | * @return A char[] containing hexadecimal characters in the selected case 228 | * @since 1.4 229 | */ 230 | public static char[] encodeHex(final byte[] data, final boolean toLowerCase) { 231 | return encodeHex(data, toLowerCase ? DIGITS_LOWER : DIGITS_UPPER); 232 | } 233 | 234 | /** 235 | * Converts an array of bytes into an array of characters representing the 236 | * hexadecimal values of each byte in order. The returned array will be 237 | * double the length of the passed array, as it takes two characters to 238 | * represent any given byte. 239 | * 240 | * @param data a byte[] to convert to Hex characters 241 | * @param toDigits the output alphabet (must contain at least 16 chars) 242 | * @return A char[] containing the appropriate characters from the alphabet 243 | * For best results, this should be either upper- or lower-case hex. 244 | * @since 1.4 245 | */ 246 | private static char[] encodeHex(final byte[] data, final char[] toDigits) { 247 | final int l = data.length; 248 | final char[] out = new char[l << 1]; 249 | // two characters form the hex value. 250 | for (int i = 0, j = 0; i < l; i++) { 251 | out[j++] = toDigits[(0xF0 & data[i]) >>> 4]; 252 | out[j++] = toDigits[0x0F & data[i]]; 253 | } 254 | return out; 255 | } 256 | } --------------------------------------------------------------------------------