1、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
2、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
3、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
4、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
5、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
6、public static boolean isNotBlank(CharSequence cs)
原理同上。
- StringUtils.isNotBlank(null) = false
- StringUtils.isNotBlank("") = false
- StringUtils.isNotBlank(" ") = false
- StringUtils.isNotBlank("bob") = true
- StringUtils.isNotBlank(" bob ") = true
7、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
8、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
9、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。
- StringUtils.trim(null) = null
- StringUtils.trim("") = ""
- StringUtils.trim(" ") = ""
- StringUtils.trim("abc") = "abc"
- StringUtils.trim(" abc ") = "abc"
变体有,不常用,跟trim()方法类似。
- public static String trimToNull(String str)
- public static String trimToEmpty(String str)
10、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"
11、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
12、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
13、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
14、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
15、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
16、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
17、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
18、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
19、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"
这三个方法类似都是截取字符串。
- 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)
20、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"]
21、public static 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"
22、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"
23、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"
24、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"
25、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"
26、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"
27、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 "
28、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"
29、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"
30、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
31、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"
32、public static String reverse(String str)
字符串翻转。
- StringUtils.reverse(null) = null
- StringUtils.reverse("") = ""
- StringUtils.reverse("bat") = "tab"
33、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
34、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
35、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\"\""