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StringUtils.isEmpty()和StringUtils.isB的区别

Moshow郑锴 人气:2

也许你两个都不知道,也许你除了isEmpty/isNotEmpty/isNotBlank/isBlank外,并不知道还有isAnyEmpty/isNoneEmpty/isAnyBlank/isNoneBlank的存在, come on ,让我们一起来探索org.apache.commons.lang3.StringUtils;这个工具类.

#isEmpty系列

StringUtils.isEmpty()

>>>是否为空. 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
    /**
     *
     * <p>NOTE: This method changed in Lang version 2.0.
     * It no longer trims the CharSequence.
     * That functionality is available in isBlank().</p>
     *
     * @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

    /**
     * <p>Checks if none of the CharSequences are empty ("") or null.</p>
     *
     * <pre>
     * 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
     * </pre>
     *
     * @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) {
      return !isAnyEmpty(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
    /**
     * <p>Checks if a CharSequence is whitespace, empty ("") or null.</p>
     * @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
     /**
     * <p>Checks if any one of the CharSequences are blank ("") or null and not whitespace only..</p>
     * @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, “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
    /**
     * <p>Checks if none of the CharSequences are blank ("") or null and whitespace only..</p>
     * @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

可以参考官方的文档,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/IsBlankchecks if a String contains text检查字符串是否包含文本
Trim/Stripremoves leading and trailing whitespace删除前导和尾随空格
Equals/Comparecompares two strings null-safe比较两个字符串是否为null安全的
startsWithcheck if a String starts with a prefix null-safe检查字符串是否以前缀null安全开头
endsWithcheck 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/Containsnull-safe index-of checks包含空安全索引检查
IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyButindex-of any of a set of Strings任意一组字符串的索引
ContainsOnly/ContainsNone/ContainsAnydoes String contains only/none/any of these characters字符串是否仅包含/无/这些字符中的任何一个
Substring/Left/Right/Midnull-safe substring extractions字符串安全提取
SubstringBefore/SubstringAfter/SubstringBetweensubstring extraction relative to other strings -相对其他字符串的字符串提取 
Split/Joinsplits 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/Deleteremoves part of a String -删除字符串的一部分 
Replace/OverlaySearches a String and replaces one String with another搜索字符串,然后用另一个字符串替换
Chomp/Chopremoves the last part of a String删除字符串的最后一部分
AppendIfMissingappends a suffix to the end of the String if not present如果不存在后缀,则在字符串的末尾附加一个后缀
PrependIfMissingprepends a prefix to the start of the String if not present如果不存在前缀,则在字符串的开头添加前缀
LeftPad/RightPad/Center/Repeatpads a String填充字符串
UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalizechanges the case of a String更改字符串的大小写
CountMatchescounts 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/IsAsciiPrintablechecks the characters in a String检查字符串中的字符
DefaultStringprotects against a null input String防止输入字符串为空
Rotaterotate (circular shift) a String旋转(循环移位)字符串
Reverse/ReverseDelimitedreverses a String -反转字符串 
Abbreviateabbreviates 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
Differencecompares Strings and reports on their differences比较字符串并报告其差异
LevenshteinDistancethe number of changes needed to change one String into another将一个String转换为另一个String所需的更改次数

以上为个人经验,希望能给大家一个参考,也希望大家多多支持。

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