|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 |
public static boolean isEmpty(CharSequence cs) 常用函数之一，判断字符串是否为""或者null StringUtils.isEmpty(null) = true StringUtils.isEmpty("") = true StringUtils.isEmpty(" ") = false StringUtils.isEmpty("bob") = false StringUtils.isEmpty(" bob ") = false public static boolean isNotEmpty(CharSequence cs) 最常用函数之一，跟上面方法相对 StringUtils.isNotEmpty(null) = false StringUtils.isNotEmpty("") = false StringUtils.isNotEmpty(" ") = true StringUtils.isNotEmpty("bob") = true StringUtils.isNotEmpty(" bob ") = true public static boolean isAnyEmpty(CharSequence... css) 任意一个参数为空的话，返回true，如果这些参数都不为空的话返回false。 在写一些判断条件的时候，这个方法还是很实用的。 StringUtils.isAnyEmpty(null) = true StringUtils.isAnyEmpty(null, "foo") = true StringUtils.isAnyEmpty("", "bar") = true StringUtils.isAnyEmpty("bob", "") = true StringUtils.isAnyEmpty(" bob ", null) = true StringUtils.isAnyEmpty(" ", "bar") = false StringUtils.isAnyEmpty("foo", "bar") = false public static boolean isNoneEmpty(CharSequence... css) 任意一个参数是空，返回false 所有参数都不为空，返回true 注意这些方法的用法 StringUtils.isNoneEmpty(null) = false StringUtils.isNoneEmpty(null, "foo") = false StringUtils.isNoneEmpty("", "bar") = false StringUtils.isNoneEmpty("bob", "") = false StringUtils.isNoneEmpty(" bob ", null) = false StringUtils.isNoneEmpty(" ", "bar") = true StringUtils.isNoneEmpty("foo", "bar") = true public static boolean isBlank(CharSequence cs) 判断字符对象是不是空字符串，注意与isEmpty的区别 StringUtils.isBlank(null) = true StringUtils.isBlank("") = true StringUtils.isBlank(" ") = true StringUtils.isBlank("bob") = false StringUtils.isBlank(" bob ") = false public static boolean isNotBlank(CharSequence cs) StringUtils.isNotBlank(null) = false StringUtils.isNotBlank("") = false StringUtils.isNotBlank(" ") = false StringUtils.isNotBlank("bob") = true StringUtils.isNotBlank(" bob ") = true 原理同上 public static boolean isAnyBlank(CharSequence... css) StringUtils.isAnyBlank(null) = true StringUtils.isAnyBlank(null, "foo") = true StringUtils.isAnyBlank(null, null) = true StringUtils.isAnyBlank("", "bar") = true StringUtils.isAnyBlank("bob", "") = true StringUtils.isAnyBlank(" bob ", null) = true StringUtils.isAnyBlank(" ", "bar") = true StringUtils.isAnyBlank("foo", "bar") = false public static boolean isNoneBlank(CharSequence... css) StringUtils.isNoneBlank(null) = false StringUtils.isNoneBlank(null, "foo") = false StringUtils.isNoneBlank(null, null) = false StringUtils.isNoneBlank("", "bar") = false StringUtils.isNoneBlank("bob", "") = false StringUtils.isNoneBlank(" bob ", null) = false StringUtils.isNoneBlank(" ", "bar") = false StringUtils.isNoneBlank("foo", "bar") = true public static String trim(String str) 移除字符串两端的空字符串，制表符char <= 32如：\n \t 如果为空的话，返回空 如果为"" StringUtils.trim(null) = null StringUtils.trim("") = "" StringUtils.trim(" ") = "" StringUtils.trim("abc") = "abc" StringUtils.trim(" abc ") = "abc" 变体有 public static String trimToNull(String str) public static String trimToEmpty(String str) 不常用，跟trim()方法类似 public static String strip(String str) public static String strip(String str, String stripChars) str：被处理的字符串，可为空 stripChars： 删除的字符串， StringUtils.strip(null, *) = null StringUtils.strip("", *) = "" StringUtils.strip("abc", null) = "abc" StringUtils.strip(" abc", null) = "abc" StringUtils.strip("abc ", null) = "abc" StringUtils.strip(" abc ", null) = "abc" StringUtils.strip(" abcyx", "xyz") = " abc" public static boolean equals(CharSequence cs1, CharSequence cs2) 字符串比对方法，是比较实用的方法之一，两个比较的字符串都能为空，不会报空指针异常。 StringUtils.equals(null, null) = true StringUtils.equals(null, "abc") = false StringUtils.equals("abc", null) = false StringUtils.equals("abc", "abc") = true StringUtils.equals("abc", "ABC") = false public static boolean equalsIgnoreCase(CharSequence str1, CharSequence str2) 上面方法的变体字符串比较（忽略大小写），在验证码……等字符串比较，真是很实用。 StringUtils.equalsIgnoreCase(null, null) = true StringUtils.equalsIgnoreCase(null, "abc") = false StringUtils.equalsIgnoreCase("abc", null) = false StringUtils.equalsIgnoreCase("abc", "abc") = true StringUtils.equalsIgnoreCase("abc", "ABC") = true public static int indexOf(CharSequence seq, int searchChar) indexOf这个方法不必多说，这个方法主要处理掉了空字符串的问题，不会报空指针，有一定用处 StringUtils.indexOf(null, *) = -1 StringUtils.indexOf("", *) = -1 StringUtils.indexOf("aabaabaa", 'a') = 0 StringUtils.indexOf("aabaabaa", 'b') = 2 public static int ordinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal) 字符串在另外一个字符串里，出现第Ordinal次的位置 StringUtils.ordinalIndexOf(null, *, *) = -1 StringUtils.ordinalIndexOf(*, null, *) = -1 StringUtils.ordinalIndexOf("", "", *) = 0 StringUtils.ordinalIndexOf("aabaabaa", "a", 1) = 0 StringUtils.ordinalIndexOf("aabaabaa", "a", 2) = 1 StringUtils.ordinalIndexOf("aabaabaa", "b", 1) = 2 StringUtils.ordinalIndexOf("aabaabaa", "b", 2) = 5 StringUtils.ordinalIndexOf("aabaabaa", "ab", 1) = 1 StringUtils.ordinalIndexOf("aabaabaa", "ab", 2) = 4 StringUtils.ordinalIndexOf("aabaabaa", "", 1) = 0 StringUtils.ordinalIndexOf("aabaabaa", "", 2) = 0 public static int lastIndexOf(CharSequence seq, int searchChar) 字符串最后一次出现的位置 StringUtils.lastIndexOf(null, *) = -1 StringUtils.lastIndexOf("", *) = -1 StringUtils.lastIndexOf("aabaabaa", 'a') = 7 StringUtils.lastIndexOf("aabaabaa", 'b') = 5 public static int lastOrdinalIndexOf(CharSequence str, CharSequence searchStr, int ordinal) 字符串searchStr在str里面出现倒数第ordinal出现的位置 StringUtils.lastOrdinalIndexOf(null, *, *) = -1 StringUtils.lastOrdinalIndexOf(*, null, *) = -1 StringUtils.lastOrdinalIndexOf("", "", *) = 0 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 1) = 7 StringUtils.lastOrdinalIndexOf("aabaabaa", "a", 2) = 6 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 1) = 5 StringUtils.lastOrdinalIndexOf("aabaabaa", "b", 2) = 2 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 1) = 4 StringUtils.lastOrdinalIndexOf("aabaabaa", "ab", 2) = 1 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 1) = 8 StringUtils.lastOrdinalIndexOf("aabaabaa", "", 2) = 8 public static boolean contains(CharSequence seq, int searchChar) 字符串seq是否包含searchChar StringUtils.contains(null, *) = false StringUtils.contains("", *) = false StringUtils.contains("abc", 'a') = true StringUtils.contains("abc", 'z') = false public static boolean containsAny(CharSequence cs, char... searchChars) 包含后面数组中的任意对象，返回true StringUtils.containsAny(null, *) = false StringUtils.containsAny("", *) = false StringUtils.containsAny(*, null) = false StringUtils.containsAny(*, []) = false StringUtils.containsAny("zzabyycdxx",['z','a']) = true StringUtils.containsAny("zzabyycdxx",['b','y']) = true StringUtils.containsAny("aba", ['z']) = false public static String substring(String str, int start) 字符串截取 StringUtils.substring(null, *) = null StringUtils.substring("", *) = "" StringUtils.substring("abc", 0) = "abc" StringUtils.substring("abc", 2) = "c" StringUtils.substring("abc", 4) = "" StringUtils.substring("abc", -2) = "bc" StringUtils.substring("abc", -4) = "abc" public static String left(String str, int len) public static String right(String str, int len) public static String mid(String str, int pos, int len) 这三个方法类似都是截取字符串 public static String[] split(String str, String separatorChars) 字符串分割 StringUtils.split(null, *) = null StringUtils.split("", *) = [] StringUtils.split("abc def", null) = ["abc", "def"] StringUtils.split("abc def", " ") = ["abc", "def"] StringUtils.split("abc def", " ") = ["abc", "def"] StringUtils.split("ab:cd:ef", ":") = ["ab", "cd", "ef"] public static <T> String join(T... elements) 字符串连接 StringUtils.join(null) = null StringUtils.join([]) = "" StringUtils.join([null]) = "" StringUtils.join(["a", "b", "c"]) = "abc" StringUtils.join([null, "", "a"]) = "a" public static String join(Object[] array, char separator) 特定字符串连接数组，很多情况下还是蛮实用，不用自己取拼字符串 StringUtils.join(null, *) = null StringUtils.join([], *) = "" StringUtils.join([null], *) = "" StringUtils.join(["a", "b", "c"], ';') = "a;b;c" StringUtils.join(["a", "b", "c"], null) = "abc" StringUtils.join([null, "", "a"], ';') = ";;a" public static String deleteWhitespace(String str) 删除空格 StringUtils.deleteWhitespace(null) = null StringUtils.deleteWhitespace("") = "" StringUtils.deleteWhitespace("abc") = "abc" StringUtils.deleteWhitespace(" ab c ") = "abc" public static String removeStart(String str, String remove) 删除以特定字符串开头的字符串，如果没有的话，就不删除。 StringUtils.removeStart(null, *) = null StringUtils.removeStart("", *) = "" StringUtils.removeStart(*, null) = * StringUtils.removeStart("www.domain.com", "www.") = "domain.com" StringUtils.removeStart("domain.com", "www.") = "domain.com" StringUtils.removeStart("www.domain.com", "domain") = "www.domain.com" StringUtils.removeStart("abc", "") = "abc" public static String rightPad(String str,int size,char padChar) 生成订单号，的时候还是很实用的。右边自动补齐。 StringUtils.rightPad(null, *, *) = null StringUtils.rightPad("", 3, 'z') = "zzz" StringUtils.rightPad("bat", 3, 'z') = "bat" StringUtils.rightPad("bat", 5, 'z') = "batzz" StringUtils.rightPad("bat", 1, 'z') = "bat" StringUtils.rightPad("bat", -1, 'z') = "bat" public static String leftPad(String str, int size,char padChar) 左边自动补齐 StringUtils.leftPad(null, *, *) = null StringUtils.leftPad("", 3, 'z') = "zzz" StringUtils.leftPad("bat", 3, 'z') = "bat" StringUtils.leftPad("bat", 5, 'z') = "zzbat" StringUtils.leftPad("bat", 1, 'z') = "bat" StringUtils.leftPad("bat", -1, 'z') = "bat" public static String center(String str,int size) 将字符在某特定长度下，句子 StringUtils.center(null, *) = null StringUtils.center("", 4) = " " StringUtils.center("ab", -1) = "ab" StringUtils.center("ab", 4) = " ab " StringUtils.center("abcd", 2) = "abcd" StringUtils.center("a", 4) = " a " public static String capitalize(String str) 首字母大写 StringUtils.capitalize(null) = null StringUtils.capitalize("") = "" StringUtils.capitalize("cat") = "Cat" StringUtils.capitalize("cAt") = "CAt" public static String swapCase(String str) 反向大小写 StringUtils.swapCase(null) = null StringUtils.swapCase("") = "" StringUtils.swapCase("The dog has a BONE") = "tHE DOG HAS A bone" public static boolean isAlpha(CharSequence cs) 判断字符串是否由字母组成 StringUtils.isAlpha(null) = false StringUtils.isAlpha("") = false StringUtils.isAlpha(" ") = false StringUtils.isAlpha("abc") = true StringUtils.isAlpha("ab2c") = false StringUtils.isAlpha("ab-c") = false public static String defaultString(String str, String defaultStr) 默认字符串，相当于三目运算，前面弱为空，则返回后面一个参数 StringUtils.defaultString(null, "NULL") = "NULL" StringUtils.defaultString("", "NULL") = "" StringUtils.defaultString("bat", "NULL") = "bat" public static String reverse(String str) 字符串翻转 StringUtils.reverse(null) = null StringUtils.reverse("") = "" StringUtils.reverse("bat") = "tab" public static String abbreviate(String str, int maxWidth) 缩略字符串，省略号要占三位。maxWith小于3位会报错。 StringUtils.abbreviate(null, *) = null StringUtils.abbreviate("", 4) = "" StringUtils.abbreviate("abcdefg", 6) = "abc..." StringUtils.abbreviate("abcdefg", 7) = "abcdefg" StringUtils.abbreviate("abcdefg", 8) = "abcdefg" StringUtils.abbreviate("abcdefg", 4) = "a..." StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException public static String abbreviate(String str, int offset, int maxWidth) 缩略字符串的一些高级用法 StringUtils.abbreviate(null, *, *) = null StringUtils.abbreviate("", 0, 4) = "" StringUtils.abbreviate("abcdefghijklmno", -1, 10) = "abcdefg..." StringUtils.abbreviate("abcdefghijklmno", 0, 10) = "abcdefg..." StringUtils.abbreviate("abcdefghijklmno", 1, 10) = "abcdefg..." StringUtils.abbreviate("abcdefghijklmno", 4, 10) = "abcdefg..." StringUtils.abbreviate("abcdefghijklmno", 5, 10) = "...fghi..." StringUtils.abbreviate("abcdefghijklmno", 6, 10) = "...ghij..." StringUtils.abbreviate("abcdefghijklmno", 8, 10) = "...ijklmno" StringUtils.abbreviate("abcdefghijklmno", 10, 10) = "...ijklmno" StringUtils.abbreviate("abcdefghijklmno", 12, 10) = "...ijklmno" StringUtils.abbreviate("abcdefghij", 0, 3) = IllegalArgumentException StringUtils.abbreviate("abcdefghij", 5, 6) = IllegalArgumentException public static String wrap(String str, char wrapWith) 包装，用后面的字符串对前面的字符串进行包装 StringUtils.wrap(null, *) = null StringUtils.wrap("", *) = "" StringUtils.wrap("ab", '\0') = "ab" StringUtils.wrap("ab", 'x') = "xabx" StringUtils.wrap("ab", '\'') = "'ab'" StringUtils.wrap("\"ab\"", '\"') = "\"\"ab\"\"" |
支付宝扫一扫![Java 中 MongoDB 分页查询的总结_[转]12498158的技术博客_51CTO博客](https://hangzhou01.oss-cn-hangzhou.aliyuncs.com/uploads/2017/06/images80c8bd39f14f0f6753ebd3bb6a33f35d.png)
