isEmpty 和 isBlank 的用法区别，至少一半的人答不上来...

isEmpty系列

StringUtils.isEmpty()

是用法否为空. 可以看到 " " 空格是会绕过这种空判断,因为是一个空格,并不是严格的空值,会导致 isEmpty(" ")=false

StringUtils.isEmpty(null) = true

StringUtils.isEmpty("") = true

StringUtils.isEmpty(" ") = false

StringUtils.isEmpty("bob") = false

StringUtils.isEmpty(" bob ") = false

/

**

*

*

NOTE: This method changed in Lang version 2.0.

* It no longer trims the CharSequence.

* That functionality is available in isBlank().

*

* @param cs the CharSequence to check, may be null

* @return { @code true} if the CharSequence is empty or null

* @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)

*/

public static boolean isEmpty(final CharSequence cs) {

return cs == null || cs.length() == 0;

}StringUtils.isNotEmpty()

相当于不为空 , = !isEmpty()。

public static boolean isNotEmpty(final CharSequence cs) {

return !isEmpty(cs);

}StringUtils.isAnyEmpty()

是区别否有一个为空,只有一个为空,就为true

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

/

**

* @param css the CharSequences to check, may be null or empty

* @return { @code true} if any of the CharSequences are empty or null

* @since 3.2

*/

public static boolean isAnyEmpty(final CharSequence... css) {

if (ArrayUtils.isEmpty(css)) {

return true;

}

for (final CharSequence cs : css){

if (isEmpty(cs)) {

return true;

}

}

return false;

}StringUtils.isNoneEmpty()

相当于!isAnyEmpty(css) , 必须所有的值都不为空才返回true

/

**

*

Checks if none of the CharSequences are empty ("") or null.

*

*

* 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

*

*

* @param css the CharSequences to check, may be null or empty

* @return { @code true} if none of the CharSequences are empty or null

* @since 3.2

*/

public static boolean isNoneEmpty(final CharSequence... css) {

isBank系列

StringUtils.isBlank()

是否为真空值(空格或者空值)

StringUtils.isBlank(null) = true

StringUtils.isBlank("") = true

StringUtils.isBlank(" ") = true

StringUtils.isBlank("bob") = false

StringUtils.isBlank(" bob ") = false

/

**

*

Checks if a CharSequence is whitespace, empty ("") or null.

* @param cs the CharSequence to check, may be null

* @return { @code true} if the CharSequence is null, empty or whitespace

* @since 2.0

* @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)

*/

public static boolean isBlank(final CharSequence cs) {

int strLen;

if (cs == null || (strLen = cs.length()) == 0) {

return true;

}

for (int i = 0; i < strLen; i++) {

if (Character.isWhitespace(cs.charAt(i)) == false) {

return false;

}

}

return true;

}StringUtils.isNotBlank()

是否真的不为空,不是空格或者空值 ,相当于!isBlank();

public static boolean isNotBlank(final CharSequence cs) {

return !isBlank(cs);

}StringUtils.isAnyBlank()

是否包含任何真空值(包含空格或空值)

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

/

**

*

Checks if any one of the CharSequences are blank ("") or null and not whitespace only..

* @param css the CharSequences to check, may be null or empty

* @return { @code true} if any of the CharSequences are blank or null or whitespace only

* @since 3.2

*/

public static boolean isAnyBlank(final CharSequence... css) {

if (ArrayUtils.isEmpty(css)) {

return true;

}

for (final CharSequence cs : css){

if (isBlank(cs)) {

return true;

}

}

return false;

}StringUtils.isNoneBlank()

是否全部都不包含空值或空格。

StringUtils.isNoneBlank(null) = false

StringUtils.isNoneBlank(null,至少 "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

/

**

*

Checks if none of the CharSequences are blank ("") or null and whitespace only..

* @param css the CharSequences to check, may be null or empty

* @return { @code true} if none of the CharSequences are blank or null or whitespace only

* @since 3.2

*/

public static boolean isNoneBlank(final CharSequence... css) {

return !isAnyBlank(css);

}

StringUtils的源码下载其他方法。

可以参考官方的半的不上文档,里面有详细的描述,有些方法还是很好用的。

https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html

方法名

英文解释

中文解释

IsEmpty/IsBlank

checks if a String contains text

检查字符串是人答否包含文本

Trim/Strip

removes leading and trailing whitespace

删除前导和尾随空格

Equals/Compare

compares two strings null-safe

比较两个字符串是否为null安全的

startsWith

check if a String starts with a prefix null-safe

检查字符串是否以前缀null安全开头

endsWith

check if a String ends with a suffix null-safe

检查字符串是否以后缀null安全结尾

IndexOf/LastIndexOf/Contains

null-safe index-of checks

包含空安全索引检查

IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut

index-of any of a set of Strings

任意一组字符串的索引

ContainsOnly/ContainsNone/ContainsAny

does String contains only/none/any of these characters

字符串是否仅包含/无/这些字符中的云南idc服务商任何一个

Substring/Left/Right/Mid

null-safe substring extractions

字符串安全提取

SubstringBefore/SubstringAfter/SubstringBetween

substring extraction relative to other strings -相对其他字符串的字符串提取

Split/Join

splits a String into an array of substrings and vice versa

将字符串拆分为子字符串数组，反之亦然

Remove/Delete

removes part of a String -删除字符串的用法一部分

Replace/Overlay

Searches a String and replaces one String with another

搜索字符串，然后用另一个字符串替换

Chomp/Chop

removes the last part of a String

删除字符串的区别最后一部分

AppendIfMissing

appends a suffix to the end of the String if not present

如果不存在后缀，则在字符串的至少末尾附加一个后缀

PrependIfMissing

prepends a prefix to the start of the String if not present

如果不存在前缀，则在字符串的半的不上开头添加前缀

LeftPad/RightPad/Center/Repeat

pads a String

填充字符串

UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize

changes the case of a String

更改字符串的大小写

CountMatches

counts the number of occurrences of one String in another

计算一个字符串在另一个字符串中出现的次数

IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable

checks the characters in a String

检查字符串中的字符

DefaultString

protects against a null input String

防止输入字符串为空

Rotate

rotate (circular shift) a String

旋转（循环移位）字符串

Reverse/ReverseDelimited

reverses a String -反转字符串

Abbreviate

abbreviates a string using ellipsis or another given String

使用省略号或另一个给定的String缩写一个字符串

Difference

compares Strings and reports on their differences

比较字符串并报告其差异

LevenshteinDistance

the number of changes needed to change one String into another

将一个String转换为另一个String所需的香港云服务器更改次数

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