码农不识Apache，码尽一生也枉然。
判断空字符串 isEmpty(CharSequence cs) 判断是否是空字符串，代码示例：
1 2 3 4 5 StringUtils.isEmpty(null ) = true StringUtils.isEmpty("" ) = true StringUtils.isEmpty(" " ) = false StringUtils.isEmpty("bob" ) = false StringUtils.isEmpty(" bob " ) = false
isNotEmpty(CharSequence cs) 判断是否不是空字符串，与isEmpty(CharSequence cs)相反。
isAnyEmpty(CharSequence… css) 判断是否含有空字符串，代码示例：
1 2 3 4 5 6 7 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
isNoneEmpty(CharSequence… css) 判断是否都不是空字符串，与isAnyEmpty(CharSequence... css)相反。
isAllEmpty(CharSequence… css) 判断是否都是空字符串，代码示例：
1 2 3 4 5 6 7 8 9 StringUtils.isAllEmpty(null ) = true StringUtils.isAllEmpty(null , "" ) = true StringUtils.isAllEmpty(new String[] {}) = true StringUtils.isAllEmpty(null , "foo" ) = false StringUtils.isAllEmpty("" , "bar" ) = false StringUtils.isAllEmpty("bob" , "" ) = false StringUtils.isAllEmpty(" bob " , null ) = false StringUtils.isAllEmpty(" " , "bar" ) = false StringUtils.isAllEmpty("foo" , "bar" ) = false
isBlank(CharSequence cs) 判断是否是“大空字符串”，代码示例：
1 2 3 4 5 StringUtils.isBlank(null ) = true StringUtils.isBlank("" ) = true StringUtils.isBlank(" " ) = true StringUtils.isBlank("bob" ) = false StringUtils.isBlank(" bob " ) = false
isNotBlank(CharSequence cs) 判断是否不是“大空字符串”，与isBlank(CharSequence cs)相反，与isNotEmpty(CharSequence cs)相似。
isAnyBlank(CharSequence… css) 判断是否有“大空字符串”，与isAnyEmpty(CharSequence... css)相似。
isNoneBlank(CharSequence… css) 判断是否都不是“大空字符串”，与isAnyBlank(CharSequence... css)相反，与isNoneEmpty(CharSequence... css)相似。
isAllBlank(CharSequence… css) 判断是否都是“大空字符串”，与isAllEmpty(CharSequence... css)相似。
截取字符串 trim(String str) 去除字符串前后的控制符，代码示例：
1 2 3 4 5 StringUtils.trim(null ) = null StringUtils.trim("" ) = "" StringUtils.trim(" " ) = "" StringUtils.trim("abc" ) = "abc" StringUtils.trim(" abc " ) = "abc"
trimToNull(String str) 去除字符串前后的控制符，如何是空字符串则转为null，代码示例：
1 2 3 4 5 StringUtils.trimToNull(null ) = null StringUtils.trimToNull("" ) = null StringUtils.trimToNull(" " ) = null StringUtils.trimToNull("abc" ) = "abc" StringUtils.trimToNull(" abc " ) = "abc"
trimToEmpty(String str) 去除字符串前后的控制符，如何是null则转为空字符串，代码示例：
1 2 3 4 5 StringUtils.trimToEmpty(null ) = "" StringUtils.trimToEmpty("" ) = "" StringUtils.trimToEmpty(" " ) = "" StringUtils.trimToEmpty("abc" ) = "abc" StringUtils.trimToEmpty(" abc " ) = "abc"
truncate(String str, int maxWidth) 截断字符串，具有以下特点：
如果str字符串的长度小于maxWidth，则直接返回str。
不满足第一条时，则为substring(str, 0, maxWidth)。
如果maxWidth小于0，则抛出IllegalArgumentException。
在任何情况下都不会返回长度大于maxWidth的字符串。
代码示例：
1 2 3 4 5 6 7 8 StringUtils.truncate(null , 0 ) = null StringUtils.truncate(null , 2 ) = null StringUtils.truncate("" , 4 ) = "" StringUtils.truncate("abcdefg" , 4 ) = "abcd" StringUtils.truncate("abcdefg" , 6 ) = "abcdef" StringUtils.truncate("abcdefg" , 7 ) = "abcdefg" StringUtils.truncate("abcdefg" , 8 ) = "abcdefg" StringUtils.truncate("abcdefg" , -1 ) = throws an IllegalArgumentException
truncate(String str, int offset, int maxWidth) 截断字符串，具有以下特点：
如果str字符串的长度小于maxWidth，则直接返回str。
不满足第一条时，则为substring(str, offset, maxWidth)。
如果maxWidth或者offset小于0，则抛出IllegalArgumentException。
在任何情况下都不会返回长度大于maxWidth的字符串。
代码示例：
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 StringUtils.truncate(null , 0 , 0 ) = null StringUtils.truncate(null , 2 , 4 ) = null StringUtils.truncate("" , 0 , 10 ) = "" StringUtils.truncate("" , 2 , 10 ) = "" StringUtils.truncate("abcdefghij" , 0 , 3 ) = "abc" StringUtils.truncate("abcdefghij" , 5 , 6 ) = "fghij" StringUtils.truncate("raspberry peach" , 10 , 15 ) = "peach" StringUtils.truncate("abcdefghijklmno" , 0 , 10 ) = "abcdefghij" StringUtils.truncate("abcdefghijklmno" , -1 , 10 ) = throws an IllegalArgumentException StringUtils.truncate("abcdefghijklmno" , Integer.MIN_VALUE, 10 ) = "abcdefghij" StringUtils.truncate("abcdefghijklmno" , Integer.MIN_VALUE, Integer.MAX_VALUE) = "abcdefghijklmno" StringUtils.truncate("abcdefghijklmno" , 0 , Integer.MAX_VALUE) = "abcdefghijklmno" StringUtils.truncate("abcdefghijklmno" , 1 , 10 ) = "bcdefghijk" StringUtils.truncate("abcdefghijklmno" , 2 , 10 ) = "cdefghijkl" StringUtils.truncate("abcdefghijklmno" , 3 , 10 ) = "defghijklm" StringUtils.truncate("abcdefghijklmno" , 4 , 10 ) = "efghijklmn" StringUtils.truncate("abcdefghijklmno" , 5 , 10 ) = "fghijklmno" StringUtils.truncate("abcdefghijklmno" , 5 , 5 ) = "fghij" StringUtils.truncate("abcdefghijklmno" , 5 , 3 ) = "fgh" StringUtils.truncate("abcdefghijklmno" , 10 , 3 ) = "klm" StringUtils.truncate("abcdefghijklmno" , 10 , Integer.MAX_VALUE) = "klmno" StringUtils.truncate("abcdefghijklmno" , 13 , 1 ) = "n" StringUtils.truncate("abcdefghijklmno" , 13 , Integer.MAX_VALUE) = "no" StringUtils.truncate("abcdefghijklmno" , 14 , 1 ) = "o" StringUtils.truncate("abcdefghijklmno" , 14 , Integer.MAX_VALUE) = "o" StringUtils.truncate("abcdefghijklmno" , 15 , 1 ) = "" StringUtils.truncate("abcdefghijklmno" , 15 , Integer.MAX_VALUE) = "" StringUtils.truncate("abcdefghijklmno" , Integer.MAX_VALUE, Integer.MAX_VALUE) = "" StringUtils.truncate("abcdefghij" , 3 , -1 ) = throws an IllegalArgumentException StringUtils.truncate("abcdefghij" , -2 , 4 ) = throws an IllegalArgumentException
left(String str, int len) 得到一个字符串最左边的len个字符
1 2 3 StringUtils.left("abc" , 0 ) = "" StringUtils.left("abc" , 2 ) = "ab" StringUtils.left("abc" , 4 ) = "abc"
right(String str, int len) 同left(String str, int len)相反，从右边截取len个字符。
mid(String str, int pos, int len) 得到一个字符串中间的len个字符。
1 2 3 4 5 StringUtils.mid("abc" , 0 , 2 ) = "ab" StringUtils.mid("abc" , 0 , 4 ) = "abc" StringUtils.mid("abc" , 2 , 4 ) = "c" StringUtils.mid("abc" , 4 , 2 ) = "" StringUtils.mid("abc" , -2 , 2 ) = "ab"
substringBefore(String str, String separator) 得到一个字符串第一个分隔符字符串之前的字符串。
1 2 3 4 5 6 StringUtils.substringBefore("abc" , "a" ) = "" StringUtils.substringBefore("abcba" , "b" ) = "a" StringUtils.substringBefore("abc" , "c" ) = "ab" StringUtils.substringBefore("abc" , "d" ) = "abc" StringUtils.substringBefore("abc" , "" ) = "" StringUtils.substringBefore("abc" , null ) = "abc"
substringAfter(String str, String separator) 同substringBefore(String str, String separator)相反。得到一个字符串第一个分隔符字符串之后的字符串。
substringBetween(String str, String open, String close) 得到一个字符串两个字符串之间字符串。
1 2 3 4 5 6 StringUtils.substringBetween("" , "" , "" ) = "" StringUtils.substringBetween("" , "" , "]" ) = null StringUtils.substringBetween("" , "[" , "]" ) = null StringUtils.substringBetween("yabcz" , "" , "" ) = "" StringUtils.substringBetween("yabcz" , "y" , "z" ) = "abc" StringUtils.substringBetween("yabczyabcz" , "y" , "z" ) = "abc"
substringBetween(String str, String tag) 是substringBetween(String str, String open, String close)的特殊情形。得到一个字符串中同一个字符串之间的字符串。
比较字符串 equals(CharSequence cs1, CharSequence cs2) 判断两字符串相等，代码示例：
1 2 3 4 5 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
equalsIgnoreCase(CharSequence str1, CharSequence str2) 判断两字符串相等，忽略大小写，代码示例：
1 2 3 4 5 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
equalsAny(CharSequence string, CharSequence… searchStrings) 比较一个字符串是否与其后的某个字符串相等，代码示例：
1 2 3 4 5 6 StringUtils.equalsAny(null , (CharSequence[]) null ) = false StringUtils.equalsAny(null , null , null ) = true StringUtils.equalsAny(null , "abc" , "def" ) = false StringUtils.equalsAny("abc" , null , "def" ) = false StringUtils.equalsAny("abc" , "abc" , "def" ) = true StringUtils.equalsAny("abc" , "ABC" , "DEF" ) = false
equalsAnyIgnoreCase(CharSequence string, CharSequence…searchStrings) 比较一个字符串是否与其后的某个字符串相等，忽略大小写，代码示例：
1 2 3 4 5 6 StringUtils.equalsAnyIgnoreCase(null , (CharSequence[]) null ) = false StringUtils.equalsAnyIgnoreCase(null , null , null ) = true StringUtils.equalsAnyIgnoreCase(null , "abc" , "def" ) = false StringUtils.equalsAnyIgnoreCase("abc" , null , "def" ) = false StringUtils.equalsAnyIgnoreCase("abc" , "abc" , "def" ) = true StringUtils.equalsAnyIgnoreCase("abc" , "ABC" , "DEF" ) = true
compare(String str1, String str2) 比较两字符串的大小，代码示例：
1 2 3 4 5 6 7 8 StringUtils.compare(null , null ) = 0 StringUtils.compare(null , "a" ) < 0 StringUtils.compare("a" , null ) > 0 StringUtils.compare("abc" , "abc" ) = 0 StringUtils.compare("a" , "b" ) < 0 StringUtils.compare("b" , "a" ) > 0 StringUtils.compare("a" , "B" ) > 0 StringUtils.compare("ab" , "abc" ) < 0
compareIgnoreCase(String str1, String str2) 比较两字符串的大小，忽略大小写，代码示例：
1 2 3 4 5 6 7 8 9 10 StringUtils.compareIgnoreCase(null , null ) = 0 StringUtils.compareIgnoreCase(null , "a" ) < 0 StringUtils.compareIgnoreCase("a" , null ) > 0 StringUtils.compareIgnoreCase("abc" , "abc" ) = 0 StringUtils.compareIgnoreCase("abc" , "ABC" ) = 0 StringUtils.compareIgnoreCase("a" , "b" ) < 0 StringUtils.compareIgnoreCase("b" , "a" ) > 0 StringUtils.compareIgnoreCase("a" , "B" ) < 0 StringUtils.compareIgnoreCase("A" , "b" ) < 0 StringUtils.compareIgnoreCase("ab" , "ABC" ) < 0
查找元素 indexOf(CharSequence seq, int searchChar) 查找某个字符在字符串中第一次出现时的索引位置，代码示例：
1 2 StringUtils.indexOf("aabaabaa" , 'a' ) = 0 StringUtils.indexOf("aabaabaa" , 'b' ) = 2
indexOf(CharSequence seq, CharSequence searchSeq) 同indexOf(CharSequence seq, int searchChar)相似。
1 2 3 4 5 StringUtils.indexOf("aabaabaa" , "c" ) = -1 StringUtils.indexOf("aabaabaa" , "a" ) = 0 StringUtils.indexOf("aabaabaa" , "b" ) = 2 StringUtils.indexOf("aabaabaa" , "ab" ) = 1 StringUtils.indexOf("aabaabaa" , "" ) = 0
indexOf(final CharSequence seq, final CharSequence searchSeq, final int startPos) 同indexOf(CharSequence seq, int searchChar)相似。
1 2 3 4 5 6 7 8 StringUtils.indexOf("aabaabaa" , "a" , 0 ) = 0 StringUtils.indexOf("aabaabaa" , "b" , 0 ) = 2 StringUtils.indexOf("aabaabaa" , "ab" , 0 ) = 1 StringUtils.indexOf("aabaabaa" , "b" , 3 ) = 5 StringUtils.indexOf("aabaabaa" , "b" , 9 ) = -1 StringUtils.indexOf("aabaabaa" , "b" , -1 ) = 2 StringUtils.indexOf("aabaabaa" , "" , 2 ) = 2 StringUtils.indexOf("abc" , "" , 9 ) = 3
indexOfIgnoreCase(CharSequence str, CharSequence searchStr) 同indexOf(CharSequence seq, int searchChar)相似,忽略大小写。
lastIndexOf(CharSequence seq, int searchChar) 同indexOf(CharSequence seq, int searchChar)相似，从后面开始查找。
contains(CharSequence seq, CharSequence searchSeq) 判断某字符串是否包含某子字符串。
1 2 3 4 StringUtils.contains("" , "" ) = true StringUtils.contains("abc" , "" ) = true StringUtils.contains("abc" , "a" ) = true StringUtils.contains("abc" , "z" ) = false
containsIgnoreCase(CharSequence str, CharSequence searchStr) 同contains(CharSequence seq, CharSequence searchSeq)相似，忽略大小写。
containsWhitespace(final CharSequence seq) 是contains(CharSequence seq, CharSequence searchSeq)的特殊情形，判断是否包含空白字符。
containsAny(CharSequence cs, CharSequence… searchCharSequences) 判断某字符串是否包含其后的任意一个字符串。
1 2 3 StringUtils.containsAny("abcd" , "ab" , null ) = true StringUtils.containsAny("abcd" , "ab" , "cd" ) = true StringUtils.containsAny("abc" , "d" , "abc" ) = true
containsNone(CharSequence cs, String invalidChars) 判断某字符串是否不含其后字符串的任意一个字符。
1 2 3 4 StringUtils.containsNone("ab" , "" ) = true StringUtils.containsNone("abab" , "xyz" ) = true StringUtils.containsNone("ab1" , "xyz" ) = true StringUtils.containsNone("abz" , "xyz" ) = false
分割字符串 split(String str, String separatorChars) 将某字符串按字符分割成数组，默认按空格分组。
1 2 3 4 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" ]
split(String str, String separatorChars, int max) 将某字符串按字符分割成最大max长度的数组，默认按空格分组。
1 2 3 4 StringUtils.split("ab cd ef" , null , 0 ) = ["ab" , "cd" , "ef" ] StringUtils.split("ab cd ef" , null , 0 ) = ["ab" , "cd" , "ef" ] StringUtils.split("ab:cd:ef" , ":" , 0 ) = ["ab" , "cd" , "ef" ] StringUtils.split("ab:cd:ef" , ":" , 2 ) = ["ab" , "cd:ef" ]
splitByCharacterType(final String str) 按字符串类型划分字符串为数组。
1 2 3 4 5 6 7 8 9 StringUtils.splitByCharacterType(null ) = null StringUtils.splitByCharacterType("" ) = [] StringUtils.splitByCharacterType("ab de fg" ) = ["ab" , " " , "de" , " " , "fg" ] StringUtils.splitByCharacterType("ab de fg" ) = ["ab" , " " , "de" , " " , "fg" ] StringUtils.splitByCharacterType("ab:cd:ef" ) = ["ab" , ":" , "cd" , ":" , "ef" ] StringUtils.splitByCharacterType("number5" ) = ["number" , "5" ] StringUtils.splitByCharacterType("fooBar" ) = ["foo" , "B" , "ar" ] StringUtils.splitByCharacterType("foo200Bar" ) = ["foo" , "200" , "B" , "ar" ] StringUtils.splitByCharacterType("ASFRules" ) = ["ASFR" , "ules" ]
连接字符串 join(T… elements) 无连接符连接字符串。
1 2 3 4 5 StringUtils.join(null ) = null StringUtils.join([]) = "" StringUtils.join([null ]) = "" StringUtils.join(["a" , "b" , "c" ]) = "abc" StringUtils.join([null , "" , "a" ]) = "a"
join(Object[] array, String separator) 将提供的数组按连接符连成字符串。
1 2 3 4 5 6 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"
删除字符串 deleteWhitespace(String str) 删除空白字符。
1 2 3 4 StringUtils.deleteWhitespace(null ) = null StringUtils.deleteWhitespace("" ) = "" StringUtils.deleteWhitespace("abc" ) = "abc" StringUtils.deleteWhitespace(" ab c " ) = "abc"
removeStart(String str, String remove) 删除指定字符串前缀的字符串。
1 2 3 4 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"
removeStartIgnoreCase(String str, String remove) 同removeStart(String str, String remove)相似，忽略大小写。
removeEnd(String str, String remove) 同removeStart(String str, String remove)相反。
removeEndIgnoreCase(String str, String remove) 同removeEnd(String str, String remove)相似，忽略大小写。
remove(String str, String remove) 移除字符串中指定的字符串。
1 2 StringUtils.remove("queued" , "ue" ) = "qd" StringUtils.remove("queued" , "zz" ) = "queued"
removeIgnoreCase(String str, String remove) 同remove(String str, String remove)相似，忽略大小写。
替换字符串 replace(String text, String searchString, String replacement) 替换某字符串为另一个字符串。
1 2 3 StringUtils.replace("aba" , "a" , null ) = "aba" StringUtils.replace("aba" , "a" , "" ) = "b" StringUtils.replace("aba" , "a" , "z" ) = "zbz"
replaceIgnoreCase(String text, String searchString, String replacement) 同replace(String text, String searchString, String replacement)相似，忽略大小写。
replace(String text, String searchString, String replacement, int max) 替换某字符串为另一个字符串,从左到右替换最大max次。
1 2 3 4 5 6 StringUtils.replace("abaa" , "a" , null , -1 ) = "abaa" StringUtils.replace("abaa" , "a" , "" , -1 ) = "b" StringUtils.replace("abaa" , "a" , "z" , 0 ) = "abaa" StringUtils.replace("abaa" , "a" , "z" , 1 ) = "zbaa" StringUtils.replace("abaa" , "a" , "z" , 2 ) = "zbza" StringUtils.replace("abaa" , "a" , "z" , -1 ) = "zbzz"
replaceEach(String text, String[] searchList, String[] replacementList) 替换某些字符串为另一些字符串。
1 2 3 4 5 6 7 8 StringUtils.replaceEach("aba" , null , null ) = "aba" StringUtils.replaceEach("aba" , new String[0 ], null ) = "aba" StringUtils.replaceEach("aba" , null , new String[0 ]) = "aba" StringUtils.replaceEach("aba" , new String[]{"a" }, null ) = "aba" StringUtils.replaceEach("aba" , new String[]{"a" }, new String[]{"" }) = "b" StringUtils.replaceEach("aba" , new String[]{null }, new String[]{"a" }) = "aba" StringUtils.replaceEach("abcde" , new String[]{"ab" , "d" }, new String[]{"w" , "t" }) = "wcte" StringUtils.replaceEach("abcde" , new String[]{"ab" , "d" }, new String[]{"d" , "t" }) = "dcte"
填充字符串 repeat(final String str, final int repeat) 生成重复的字符串，repeat代表生成次数。
1 2 3 4 5 6 StringUtils.repeat(null , 2 ) = null StringUtils.repeat("" , 0 ) = "" StringUtils.repeat("" , 2 ) = "" StringUtils.repeat("a" , 3 ) = "aaa" StringUtils.repeat("ab" , 2 ) = "abab" StringUtils.repeat("a" , -2 ) = ""
repeat(String str, String separator, int repeat) 生成重复的字符串，repeat代表生成次数。
1 2 3 4 5 6 StringUtils.repeat(null , null , 2 ) = null StringUtils.repeat(null , "x" , 2 ) = null StringUtils.repeat("" , null , 0 ) = "" StringUtils.repeat("" , "" , 2 ) = "" StringUtils.repeat("" , "x" , 3 ) = "xxx" StringUtils.repeat("?" , ", " , 3 ) = "?, ?, ?"
字符串计数 countMatches(CharSequence str, CharSequence sub) 计算某字符串在字符串中的出现次数。
1 2 3 4 5 StringUtils.countMatches("abba" , null ) = 0 StringUtils.countMatches("abba" , "" ) = 0 StringUtils.countMatches("abba" , "a" ) = 2 StringUtils.countMatches("abba" , "ab" ) = 1 StringUtils.countMatches("abba" , "xxx" ) = 0
字符测试 isAlpha(CharSequence cs) 判断字符串是否是Unicode字母。
1 2 3 4 5 6 StringUtils.isAlpha(null ) = false StringUtils.isAlpha("" ) = false StringUtils.isAlpha(" " ) = false StringUtils.isAlpha("abc" ) = true StringUtils.isAlpha("ab2c" ) = false StringUtils.isAlpha("ab-c" ) = false
isAlphaSpace(CharSequence cs) 同isAlpha(CharSequence cs)相似。判断字符串是否是Unicode字母或空格。
1 2 3 4 5 6 7 StringUtils.isAlphaSpace(null ) = false StringUtils.isAlphaSpace("" ) = true StringUtils.isAlphaSpace(" " ) = true StringUtils.isAlphaSpace("abc" ) = true StringUtils.isAlphaSpace("ab c" ) = true StringUtils.isAlphaSpace("ab2c" ) = false StringUtils.isAlphaSpace("ab-c" ) = false
isAlphanumeric(CharSequence cs) 同isAlpha(CharSequence cs)相似。判断字符串是否是Unicode字母或数字。
isAlphanumericSpace(CharSequence cs) 同isAlpha(CharSequence cs)相似。判断字符串是否是Unicode字母、空格或数字。
isNumeric(CharSequence cs) 判断字符串是否是数字。
1 2 3 4 5 6 7 StringUtils.isNumeric("123" ) = true StringUtils.isNumeric("12 3" ) = false StringUtils.isNumeric("ab2c" ) = false StringUtils.isNumeric("12-3" ) = false StringUtils.isNumeric("12.3" ) = false StringUtils.isNumeric("-123" ) = false StringUtils.isNumeric("+123" ) = false
isNumericSpace(CharSequence cs) 同isNumeric(CharSequence cs)相似。判断字符串是否是空格或数字。
getDigits(String str) 从字符串中提取出数字为字符串。
1 2 3 4 5 6 StringUtils.getDigits(null ) = null StringUtils.getDigits("" ) = "" StringUtils.getDigits("abc" ) = "" StringUtils.getDigits("1000$" ) = "1000" StringUtils.getDigits("1123~45" ) = "12345" StringUtils.getDigits("(541) 754-3010" ) = "5417543010"
isWhitespace(CharSequence cs) 判断是否是空格。
1 2 3 4 5 6 StringUtils.isWhitespace(null ) = false StringUtils.isWhitespace("" ) = true StringUtils.isWhitespace(" " ) = true StringUtils.isWhitespace("abc" ) = false StringUtils.isWhitespace("ab2c" ) = false StringUtils.isWhitespace("ab-c" ) = false
isAllLowerCase(CharSequence cs) 判断字符串是否都是小写。
1 2 3 4 5 6 7 8 StringUtils.isAllLowerCase(null ) = false StringUtils.isAllLowerCase("" ) = false StringUtils.isAllLowerCase(" " ) = false StringUtils.isAllLowerCase("abc" ) = true StringUtils.isAllLowerCase("abC" ) = false StringUtils.isAllLowerCase("ab c" ) = false StringUtils.isAllLowerCase("ab1c" ) = false StringUtils.isAllLowerCase("ab/c" ) = false
isAllUpperCase(CharSequence cs) 同isAllLowerCase相反。判断字符串是否都是大写。
isMixedCase(CharSequence cs) 同isAllLowerCase相似。判断字符串是否大小写都有。
默认字符串 defaultString(String str) 得到默认字符串，默认空字符串。
1 2 3 StringUtils.defaultString(null ) = "" StringUtils.defaultString("" ) = "" StringUtils.defaultString("bat" ) = "bat"
defaultString(String str, String defaultStr) 如果是null，则得到默认字符串。
1 2 3 StringUtils.defaultString(null , "NULL" ) = "NULL" StringUtils.defaultString("" , "NULL" ) = "" StringUtils.defaultString("bat" , "NULL" ) = "bat"
defaultIfEmpty(T str, T defaultStr) 同defaultString(String str, String defaultStr)相似。如果是空字符串，则得到默认字符串。
反转字符串 reverse(final String str) 反转字符串。
1 2 3 StringUtils.reverse(null ) = null StringUtils.reverse("" ) = "" StringUtils.reverse("bat" ) = "tab"
缩写字符串 abbreviate(String str, int maxWidth) 缩写字符串为最大maxWidth长度的字符串，使用...作为缩写的后缀，maxWidth不能小于等于3。
1 2 3 4 5 6 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
abbreviate(String str, String abbrevMarker, int maxWidth) 缩写字符串为最大maxWidth长度的字符串，使用abbrevMarker作为缩写的后缀，maxWidth不能小于等于abbrevMarker的长度。
1 2 3 4 5 6 7 8 StringUtils.abbreviate("" , "..." , 4 ) = "" StringUtils.abbreviate("abcdefg" , "." , 5 ) = "abcd." StringUtils.abbreviate("abcdefg" , "." , 7 ) = "abcdefg" StringUtils.abbreviate("abcdefg" , "." , 8 ) = "abcdefg" StringUtils.abbreviate("abcdefg" , ".." , 4 ) = "ab.." StringUtils.abbreviate("abcdefg" , ".." , 3 ) = "a.." StringUtils.abbreviate("abcdefg" , ".." , 2 ) = IllegalArgumentException StringUtils.abbreviate("abcdefg" , "..." , 3 ) = IllegalArgumentException
字符串钱后缀 startsWith(CharSequence str, CharSequence prefix) 判断某字符串是否包含有指定前缀的字符串。
1 2 3 4 5 StringUtils.startsWith(null , null ) = true StringUtils.startsWith(null , "abc" ) = false StringUtils.startsWith("abcdef" , null ) = false StringUtils.startsWith("abcdef" , "abc" ) = true StringUtils.startsWith("ABCDEF" , "abc" ) = false
startsWithIgnoreCase(CharSequence str, CharSequence prefix) 同startsWith(CharSequence str, CharSequence prefix)相似。忽略大小写。
startsWithAny(CharSequence sequence, CharSequence… searchStrings) 判断某字符串是否包含有其后任意一个指定前缀的字符串。
1 2 3 4 5 6 7 8 StringUtils.startsWithAny(null , null ) = false StringUtils.startsWithAny(null , new String[] {"abc" }) = false StringUtils.startsWithAny("abcxyz" , null ) = false StringUtils.startsWithAny("abcxyz" , new String[] {"" }) = true StringUtils.startsWithAny("abcxyz" , new String[] {"abc" }) = true StringUtils.startsWithAny("abcxyz" , new String[] {null , "xyz" , "abc" }) = true StringUtils.startsWithAny("abcxyz" , null , "xyz" , "ABCX" ) = false StringUtils.startsWithAny("ABCXYZ" , null , "xyz" , "abc" ) = false
endsWith(CharSequence str, CharSequence suffix) 同startsWith(CharSequence str, CharSequence prefix)相反。
endsWithIgnoreCase(CharSequence str, CharSequence suffix) 同startsWithIgnoreCase(CharSequence str, CharSequence prefix)相反。
endsWithAny(CharSequence sequence, CharSequence… searchStrings) 同startsWithAny(CharSequence sequence, CharSequence... searchStrings)相反。
