1.1.判断是否空字符串
isBlank(final CharSequence cs):判断是空字符串;
isNotBlank(final CharSequence cs):判断不是空字符串;
isEmpty(final CharSequence cs):判断是空字符串;
isNotEmpty(final CharSequence cs):判断不是空字符串;
字符串判空示例代码
StringUtils.isBlank(null); = true
StringUtils.isBlank(""); = true
StringUtils.isBlank(" "); = true
StringUtils.isBlank("bob"); = false
StringUtils.isBlank(" bob "); = false
StringUtils.isEmpty(null); = true
StringUtils.isEmpty(""); = true
StringUtils.isEmpty(" "); = false
StringUtils.isEmpty("bob"); = false
StringUtils.isEmpty(" bob "); = false
说明:isBlank和isEmpty的区别在于在于空格字符串的判断不同;简言之,Empty认为空格字符不是空字符串
1.2.判断是否存在空字符串
isAnyEmpty(final CharSequence... css):判断是否存在空字符串;
isNoneEmpty(final CharSequence... css)判断全部都不是空字符串;
isAllEmpty(final CharSequence... css):判断全部为空字符串;
isAnyBlank(final CharSequence... css):判断是否存在空字符串;
isNoneBlank(final CharSequence... css)判断全部都不是空字符串;
isAllBlank(final CharSequence... css):判断全部为空字符串;
判断是否存在空字符串示例代码
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(new String[] {}) = false
StringUtils.isAnyBlank(new String[]{""}) = true
StringUtils.isAnyBlank("foo", "bar") = false
说明:同理,这里的区别也是在于空格字符串的不同对待;
1.3.去除字符串前后空格
trim(final String str):去除字符串前后空格,同时不改变原字符串;
trimToNull(final String str):去除字符串前后空格,如果去除后是空字符串就转为null;
trimToEmpty(final String str):去除字符串前后空格,如果去除后是空字符串就转为空字符串(null转为"");
strip(final String str):这个也可以去除字符串的前后空格,不改变原字符串;
stripToNull(String str):同trimToNull(final String str)类似;
stripToEmpty(final String str):同trimToEmpty(final String str)类似;
去除字符串前后空格示例代码
StringUtils.trim(null) = null
StringUtils.trim(" ") = ""
StringUtils.trimToNull(null) = null
StringUtils.trimToNull(" ") = null
StringUtils.trimToEmpty(null) = ""
StringUtils.trimToEmpty(" ") = ""
1.4.字符串截取
truncate(final String str, final int maxWidth):截取字符串的前maxWidth个字符;
如果str的长度小于maxWidth就直接返回str;
如果maxWidth小于0则抛出IllegalArgumentException异常;
truncate(final String str, final int offset, final int maxWidth):截取指定区域的字符串;
字符串截取示例代码
StringUtils.truncate(null, 0) = null
StringUtils.truncate(null, 2) = null
StringUtils.truncate("", 4) = ""
StringUtils.truncate("abcdefg", 4) = "abcd"
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("abcdefghijklmno", -1, 10) = throws an IllegalArgumentException
StringUtils.truncate("abcdefghijklmno", Integer.MIN_VALUE, 10) = "abcdefghij"
StringUtils.truncate("abcdefghijklmno", 0, Integer.MAX_VALUE) = "abcdefghijklmno"
说明:更多的示例代码可以参考StringUtils源码;
1.5.字符串的剥离
strip(String str, final String stripChars):从str的前后剥离stripChars字符串;
stripStart(final String str, final String stripChars):从开始的地方剥离指定字符串;
stripEnd(final String str, final String stripChars):从结束的地方剥离字符串;
String[] stripAll(final String... strs):对数组中的所有字符串进行去除空格;
String[] stripAll(final String[] strs, final String stripChars):对数组中的每个字符串进行字符串剥离;
字符串的剥离示例代码
StringUtils.strip("abcde", "de"); = abc
StringUtils.strip("abcde", "ed"); = abc
StringUtils.stripStart("deabced", "ed"); = abcd
StringUtils.stripStart("deabced", "de"); = abcd
StringUtils.stripEnd(" abcyx", "xyz"); = " abc"
StringUtils.stripEnd("120.00", ".0"); = "12"
StringUtils.stripAll(["abc", " abc"]); = ["abc", "abc"]
StringUtils.stripAll(["yabcz", null], "yz"); = ["abc", null]
1.6.字符串的比较
equals(final CharSequence cs1, final CharSequence cs2):判断两个字符串是否相等;
equalsIgnoreCase(final CharSequence str1, final CharSequence str2):判断两个字符串在忽略大小写下是否相等;
compare(final String str1, final String str2):比较两个字符串长度的大小;
compareIgnoreCase(final String str1, final String str2)忽略大小写下比较两个字符串的大小;
equalsAny(final CharSequence string, final CharSequence... searchStrings):比较多字符串中是否存在相同的字符串;
equalsAnyIgnoreCase(final CharSequence string, final CharSequence...searchStrings):忽略大小写是否存在相同字符
字符串的比较代码示例
StringUtils.equals("abc", null) = false
StringUtils.equals("abc", "abc") = true
StringUtils.equals("abc", "ABC") = false
tringUtils.equalsIgnoreCase("abc", "ABC") = true
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
StringUtils.compareIgnoreCase("a", "B") < 0
StringUtils.compareIgnoreCase("A", "b") < 0
StringUtils.compareIgnoreCase("ab", "ABC") < 0
StringUtils.equalsAny("abc", "abc", "def") = true
StringUtils.equalsAny("abc", "ABC", "DEF") = false
StringUtils.equalsAnyIgnoreCase("abc", "abc", "def") = true
StringUtils.equalsAnyIgnoreCase("abc", "ABC", "DEF") = true
1.7.字符串的查找
indexOf(final CharSequence seq, final int searchChar):查找指定字符在字符串中首次出现的位置的索引值;
indexOf(final CharSequence seq, final int searchChar, final int startPos):从指定位置final int startPos开始查找;
indexOfIgnoreCase(final CharSequence str, final CharSequence searchStr):忽略大小写的查找字符串首次出现位置
indexOfIgnoreCase(final CharSequence str, final CharSequence searchStr, int startPos):同``indexOf`类似;
lastIndexOf(final CharSequence seq, final int searchChar):从尾部开始查找;
lastIndexOf(final CharSequence seq, final int searchChar, final int startPos):同理从尾部开始查找指定位置前的字符
字符串的查找示例代码
StringUtils.indexOf("aabaabaa", 'b') = 2
StringUtils.indexOf("aabaabaa", "") = 0
StringUtils.indexOf("aabaabaa", "b", 3) = 5
StringUtils.ordinalIndexOf("abababab", "abab", 3) = 4
StringUtils.lastIndexOf("aabaabaa", 'b') = 5
StringUtils.lastIndexOf("aabaabaa", 'a', 0) = 0
1.8.是否包含字符串
contains(final CharSequence seq, final int searchChar:是否包含指定字符串;
containsIgnoreCase(final CharSequence str, final CharSequence searchStr:忽略大小写下检查是否包含指定字符串
containsWhitespace(final CharSequence seq):是否包含空白字符串;
containsAny(final CharSequence cs, final char... searchChars):判断字符窜是否包含后面多个中的任意一个;
containsOnly(final CharSequence cs, final char... valid):判断前面的字符是否全部是后面的字符中的;
containsNone(final CharSequence cs, final char... searchChars):判断前面字符是否不含其后字符的任意一个字符
是否包含字符串示例代码
StringUtils.contains("abc", 'a') = true
StringUtils.contains("abc", 'z') = false
StringUtils.containsIgnoreCase("abc", "A") = true
StringUtils.containsIgnoreCase("abc", "Z") = false
StringUtils.containsWhitespace("abc") = false
StringUtils.containsWhitespace("a bc") = true
StringUtils.containsAny("zzabyycdxx",['z','a']) = true
StringUtils.containsAny("zzabyycdxx",['b','y']) = true
StringUtils.containsAny("zzabyycdxx",['z','y']) = true
StringUtils.containsAny("aba", ['z']) = false
StringUtils.containsOnly("abab", 'abc') = true
StringUtils.containsOnly("ab1", 'abc') = false
StringUtils.containsOnly("abz", 'abc') = false
StringUtils.containsNone("abab", 'xyz') = true
StringUtils.containsNone("ab1", 'xyz') = true
StringUtils.containsNone("abz", 'xyz') = false
1.9.截取字符串
substring(final String str, int start):指定开始为止截取字符串;
substring(final String str, int start):指定开始和结束为止截取字符串;
left(final String str, final int len):得到一个字符串最左边的len个字符;
right(final String str, final int len):得到一个字符串最右边的len个字符;
mid(final String str, int pos, final int len):得到中间的指定区域的字符,是左包含;
substringBefore(final String str, final String separator):得到一个字符串中第一个分割符之前的字符串;
substringAfter(final String str, final String separator):同理,得到一个字符串第一个分割符之后的字符串;
截取字符串示例代码
StringUtils.substring("abc", 2) = "c"
StringUtils.substring("abc", 4) = ""
StringUtils.substring("abc", -2) = "bc"
StringUtils.substring("abc", -4) = "abc"
StringUtils.substring("abc", 2, 2) = ""
StringUtils.substring("abc", -2, -1) = "b"
StringUtils.substring("abc", -4, 2) = "ab"
StringUtils.left("abc", 2) = "ab"
StringUtils.left("abc", 4) = "abc"
StringUtils.right("abc", 2) = "bc"
StringUtils.right("abc", 4) = "abc"
StringUtils.mid("abc", 2, 4) = "c"
StringUtils.mid("abc", 4, 2) = ""
StringUtils.mid("abc", -2, 2) = "ab"
StringUtils.substringBefore("abcba", "b") = "a"
StringUtils.substringBefore("abc", "c") = "ab"
StringUtils.substringBefore("abc", "d") = "abc"
StringUtils.substringAfter("abcba", "b") = "cba"
StringUtils.substringAfter("abc", "c") = ""
StringUtils.substringAfter("abc", "d") = ""
1.10.字符串分割
String[] split(final String str):按照空格分割字符串,返回数组;
String[] split(final String str, final char separatorChar):指定分割符分割字符串;
String[] split(final String str, final String separatorChars, final int max):指定分割符,指定最大分割的数组大小;
String[] splitByCharacterTypeCamelCase(final String str):根据字符串类型分割字符串;
字符串分割示例代码
StringUtils.split("abc def") = ["abc", "def"]
StringUtils.split(" abc ") = ["abc"]
StringUtils.split("a..b.c", '.') = ["a", "b", "c"]
StringUtils.split("a:b:c", '.') = ["a:b:c"]
StringUtils.split("a b c", ' ') = ["a", "b", "c"]
StringUtils.split("ab:cd:ef", ":", 3); = [ab, cd, ef]
StringUtils.split("ab:cd:ef", ":", 2); = [ab:cd:ef]
StringUtils.split("ab:cd:ef", ":", 1); = [ab, cd:ef]
StringUtils.splitByCharacterTypeCamelCase("number5") = ["number", "5"]
StringUtils.splitByCharacterTypeCamelCase("fooBar") = ["foo", "Bar"]
StringUtils.splitByCharacterTypeCamelCase("foo200Bar") = ["foo", "200", "Bar"]
StringUtils.splitByCharacterTypeCamelCase("ASFRules") = ["ASF", "Rules"]
1.11.字符串连接(数组转字符)
join(final T... elements);普通的连接字符串
join(final Object[] array, final char separator):指定连接符,连接字符串;
字符串连接示例代码
StringUtils.join(["a", "b", "c"]) = "abc"
StringUtils.join([null, "", "a"]) = "a"
StringUtils.join(["a", "b", "c"], ';') = "a;b;c"
StringUtils.join(["a", "b", "c"], null) = "abc"
StringUtils.join([null, "", "a"], ';') = ";;a"
1.12.删除和替换字符串
removeStart(final String str, final String remove):删除字符串中的指定的前缀字符串;
removeStartIgnoreCase(final String str, final String remove):同removeStart类似,只是忽略的大小写;
removeEnd(final String str, final String remove):同removeStart相反;
deleteWhitespace(final String str):删除字符串中的空格;
remove(final String str, final String remove):从字符串中移除指定字符串;
removeAll(final String text, final String regex):移除符合正则表达式的所有字符串;
replaceOnce(final String text, final String searchString, final String replacement):将字符串中指定字符替换一个;
replaceAll(final String text, final String regex, final String replacement):将字符串中指定字符替换所有;
删除和替换字符串示例代码
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"
StringUtils.deleteWhitespace("abc") = "abc"
StringUtils.deleteWhitespace(" ab c ") = "abc"
StringUtils.removeEnd("www.domain.com", ".com.") = "www.domain.com"
StringUtils.removeEnd("www.domain.com", ".com") = "www.domain"
StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
StringUtils.remove("queued", "ue") = "qd"
StringUtils.remove("queued", "zz") = "queued"
StringUtils.removeAll("any", ".*") = ""
StringUtils.removeAll("any", ".+") = ""
StringUtils.removeAll("abc", ".?") = ""
StringUtils.removeAll("A<__>\n<__>B", "<.*>") = "A\nB"
StringUtils.removeAll("A<__>\n<__>B", "(?s)<.*>") = "AB"
StringUtils.removeAll("ABCabc123abc", "[a-z]") = "ABC123"
StringUtils.replaceOnce("aba", "a", null) = "aba"
StringUtils.replaceOnce("aba", "a", "") = "ba"
StringUtils.replaceOnce("aba", "a", "z") = "zba"
StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "_") = "ABC_123"
StringUtils.replaceAll("ABCabc123", "[^A-Z0-9]+", "") = "ABC123"
StringUtils.replaceAll("abc", "", "ZZ") = "ZZaZZbZZcZZ"
1.13.重复字符串
repeat(final String str, final int repeat):生成指定重复次数的重复字符串;
重复字符串生成示例代码
StringUtils.repeat("a", 3) = "aaa"
StringUtils.repeat("ab", 2) = "abab"
StringUtils.repeat("a", -2) = ""
1.14.字符串出现次数
countMatches(final CharSequence str, final CharSequence sub):获取指定字符串在原字符串中出现的次数;
字符串出现次数示例代码
StringUtils.countMatches("abba", "a") = 2
StringUtils.countMatches("abba", "ab") = 1
二、StringUtils其他常用方法
2.1.判断是否是空格或者数字
isNumericSpace(final CharSequence cs)
StringUtils.isNumericSpace("12 3") = true
StringUtils.isNumericSpace("12.3") = false
2.2.判断是否是空格
isWhitespace(final CharSequence cs)
StringUtils.isWhitespace("") = true
StringUtils.isWhitespace(" ") = true
StringUtils.isWhitespace("abc") = false
2.3.判断是否全是小写
isAllLowerCase(final CharSequence cs)
StringUtils.isAllLowerCase("abc") = true
StringUtils.isAllLowerCase("abC") = false
2.4.判断是否全是大写
isAllUpperCase(final CharSequence cs)
StringUtils.isAllUpperCase("ABC") = true
StringUtils.isAllUpperCase("aBC") = false
2.5.反转字符串
reverse(final String str)
StringUtils.reverse("bat") = "tab"
2.6.字符串显示省略号
abbreviate(final String str, final int maxWidth)
StringUtils.abbreviate("abcdefg", 6) = "abc..."
StringUtils.abbreviate("abcdefg", 7) = "abcdefg"
StringUtils.abbreviate("abcdefg", 8) = "abcdefg"
StringUtils.abbreviate("abcdefg", 4) = "a..."
2.7.判断字符串是否以什么开头
startsWith(final CharSequence str, final CharSequence prefix)
StringUtils.startsWith("abcdef", null) = false
StringUtils.startsWith("abcdef", "abc") = true
StringUtils.startsWith("ABCDEF", "abc") = false
2.7.判断字符串是否以什么结尾
endsWith(final CharSequence str, final CharSequence suffix)
StringUtils.endsWith("ABCDEF", "def") = false
StringUtils.endsWith("ABCDEF", "cde") = false
StringUtils.endsWith("ABCDEF", "") = true