大家好，我是程序汪，開發(fā)中經(jīng)常有些小細節(jié)容易忽略，這些小細節(jié)往往容易導(dǎo)致代碼缺陷，今天分享一波工具類的小細節(jié)
也許你兩個都不知道,也許你除了isEmpty/isNotEmpty/isNotBlank/isBlank外,并不知道還有isAnyEmpty/isNoneEmpty/isAnyBlank/isNoneBlank的存在, come on ,讓我們一起來探索org.apache.commons.lang3.StringUtils;這個工具類。
isEmpty系列
StringUtils.isEmpty()
是否為空. 可以看到 ” ” 空格是會繞過這種空格判斷,因為是一個空格,并不是嚴格的空值,會導(dǎo)致 isEmpty(” “)=false
StringUtils.isEmpty(null) = trueStringUtils.isEmpty(“”) = trueStringUtils.isEmpty(” “) = falseStringUtils.isEmpty(“bob”) = falseStringUtils.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()
相當(dāng)于不為空 , = !isEmpty()。
public static boolean isNotEmpty(final CharSequence cs) { return !isEmpty(cs); }
StringUtils.isAnyEmpty()
是否有一個為空,只有一個為空,就為true。
StringUtils.isAnyEmpty(null) = trueStringUtils.isAnyEmpty(null, “foo”) = trueStringUtils.isAnyEmpty(“”, “bar”) = trueStringUtils.isAnyEmpty(“bob”, “”) = trueStringUtils.isAnyEmpty(” bob “, null) = trueStringUtils.isAnyEmpty(” “, “bar”) = falseStringUtils.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()
相當(dāng)于!isAnyEmpty(css) , 必須所有的值都不為空才返回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()
是否為真空值(空格或者空值)
StringUtils.isBlank(null) = trueStringUtils.isBlank(“”) = trueStringUtils.isBlank(” “) = trueStringUtils.isBlank(“bob”) = falseStringUtils.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()
是否真的不為空,不是空格或者空值 ,相當(dāng)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) = trueStringUtils.isAnyBlank(null, “foo”) = trueStringUtils.isAnyBlank(null, null) = trueStringUtils.isAnyBlank(“”, “bar”) = trueStringUtils.isAnyBlank(“bob”, “”) = trueStringUtils.isAnyBlank(” bob “, null) = trueStringUtils.isAnyBlank(” “, “bar”) = trueStringUtils.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) = falseStringUtils.isNoneBlank(null, “foo”) = falseStringUtils.isNoneBlank(null, null) = falseStringUtils.isNoneBlank(“”, “bar”) = falseStringUtils.isNoneBlank(“bob”, “”) = falseStringUtils.isNoneBlank(” bob “, null) = falseStringUtils.isNoneBlank(” “, “bar”) = falseStringUtils.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的其他方法
可以參考官方的文檔,里面有詳細的描述,有些方法還是很好用的。
https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html
方法名英文解釋中文解釋IsEmpty/IsBlankchecks if a String contains text檢查字符串是否包含文本Trim/Stripremoves leading and trailing whitespace刪除前導(dǎo)和尾隨空格Equals/Comparecompares two strings null-safe比較兩個字符串是否為null安全的startsWithcheck if a String starts with a prefix null-safe檢查字符串是否以前綴null安全開頭endsWithcheck if a String ends with a suffix null-safe檢查字符串是否以后綴null安全結(jié)尾IndexOf/LastIndexOf/Containsnull-safe index-of checks包含空安全索引檢查IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyButindex-of any of a set of Strings任意一組字符串的索引ContainsOnly/ContainsNone/ContainsAnydoes String contains only/none/any of these characters字符串是否僅包含/無/這些字符中的任何一個Substring/Left/Right/Midnull-safe substring extractions字符串安全提取SubstringBefore/SubstringAfter/SubstringBetweensubstring extraction relative to other strings -相對其他字符串的字符串提取Split/Joinsplits a String into an array of substrings and vice versa將字符串拆分為子字符串?dāng)?shù)組，反之亦然Remove/Deleteremoves part of a String -刪除字符串的一部分Replace/OverlaySearches a String and replaces one String with another搜索字符串，然后用另一個字符串替換Chomp/Chopremoves the last part of a String刪除字符串的最后一部分AppendIfMissingappends a suffix to the end of the String if not present如果不存在后綴，則在字符串的末尾附加一個后綴PrependIfMissingprepends a prefix to the start of the String if not present如果不存在前綴，則在字符串的開頭添加前綴LeftPad/RightPad/Center/Repeatpads a String填充字符串UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalizechanges the case of a String更改字符串的大小寫CountMatchescounts the number of occurrences of one String in another計算一個字符串在另一個字符串中出現(xiàn)的次數(shù)IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintablechecks the characters in a String檢查字符串中的字符DefaultStringprotects against a null input String防止輸入字符串為空Rotaterotate (circular shift) a String旋轉(zhuǎn)（循環(huán)移位）字符串Reverse/ReverseDelimitedreverses a String -反轉(zhuǎn)字符串Abbreviateabbreviates a string using ellipsis or another given String使用省略號或另一個給定的String縮寫一個字符串Differencecompares Strings and reports on their differences比較字符串并報告其差異LevenshteinDistancethe number of changes needed to change one String into another將一個String轉(zhuǎn)換為另一個String所需的更改次數(shù)
來源：https://sourl.cn/dRpJ6b
