探索StringUtils3之StringUtils.isEmpty()和StringUtils.isBlank()的区别

柔情只为你懂 2023-05-29 06:52 25阅读 0赞

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  
.

<table> 
 <thead> 
  <tr> 
   <th>方法名</th> 
   <th>英文解释</th> 
   <th>中文解释</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>IsEmpty/IsBlank</td> 
   <td>checks if a String contains text</td> 
   <td>检查字符串是否包含文本</td> 
  </tr> 
  <tr> 
   <td>Trim/Strip</td> 
   <td>removes leading and trailing whitespace</td> 
   <td>删除前导和尾随空格</td> 
  </tr> 
  <tr> 
   <td>Equals/Compare</td> 
   <td>compares two strings null-safe</td> 
   <td>比较两个字符串是否为null安全的</td> 
  </tr> 
  <tr> 
   <td>startsWith</td> 
   <td>check if a String starts with a prefix null-safe</td> 
   <td>检查字符串是否以前缀null安全开头</td> 
  </tr> 
  <tr> 
   <td>endsWith</td> 
   <td>check if a String ends with a suffix null-safe</td> 
   <td>检查字符串是否以后缀null安全结尾</td> 
  </tr> 
  <tr> 
   <td>IndexOf/LastIndexOf/Contains</td> 
   <td>null-safe index-of checks</td> 
   <td>包含空安全索引检查</td> 
  </tr> 
  <tr> 
   <td>IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut</td> 
   <td>index-of any of a set of Strings</td> 
   <td>任意一组字符串的索引</td> 
  </tr> 
  <tr> 
   <td>ContainsOnly/ContainsNone/ContainsAny</td> 
   <td>does String contains only/none/any of these characters</td> 
   <td>字符串是否仅包含/无/这些字符中的任何一个</td> 
  </tr> 
  <tr> 
   <td>Substring/Left/Right/Mid</td> 
   <td>null-safe substring extractions</td> 
   <td>字符串安全提取</td> 
  </tr> 
  <tr> 
   <td>SubstringBefore/SubstringAfter/SubstringBetween</td> 
   <td>substring extraction relative to other strings -相对其他字符串的字符串提取</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>Split/Join</td> 
   <td>splits a String into an array of substrings and vice versa</td> 
   <td>将字符串拆分为子字符串数组，反之亦然</td> 
  </tr> 
  <tr> 
   <td>Remove/Delete</td> 
   <td>removes part of a String -删除字符串的一部分</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>Replace/Overlay</td> 
   <td>Searches a String and replaces one String with another</td> 
   <td>搜索字符串，然后用另一个字符串替换</td> 
  </tr> 
  <tr> 
   <td>Chomp/Chop</td> 
   <td>removes the last part of a String</td> 
   <td>删除字符串的最后一部分</td> 
  </tr> 
  <tr> 
   <td>AppendIfMissing</td> 
   <td>appends a suffix to the end of the String if not present</td> 
   <td>如果不存在后缀，则在字符串的末尾附加一个后缀</td> 
  </tr> 
  <tr> 
   <td>PrependIfMissing</td> 
   <td>prepends a prefix to the start of the String if not present</td> 
   <td>如果不存在前缀，则在字符串的开头添加前缀</td> 
  </tr> 
  <tr> 
   <td>LeftPad/RightPad/Center/Repeat</td> 
   <td>pads a String</td> 
   <td>填充字符串</td> 
  </tr> 
  <tr> 
   <td>UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize</td> 
   <td>changes the case of a String</td> 
   <td>更改字符串的大小写</td> 
  </tr> 
  <tr> 
   <td>CountMatches</td> 
   <td>counts the number of occurrences of one String in another</td> 
   <td>计算一个字符串在另一个字符串中出现的次数</td> 
  </tr> 
  <tr> 
   <td>IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable</td> 
   <td>checks the characters in a String</td> 
   <td>检查字符串中的字符</td> 
  </tr> 
  <tr> 
   <td>DefaultString</td> 
   <td>protects against a null input String</td> 
   <td>防止输入字符串为空</td> 
  </tr> 
  <tr> 
   <td>Rotate</td> 
   <td>rotate (circular shift) a String</td> 
   <td>旋转（循环移位）字符串</td> 
  </tr> 
  <tr> 
   <td>Reverse/ReverseDelimited</td> 
   <td>reverses a String -反转字符串</td> 
   <td></td> 
  </tr> 
  <tr> 
   <td>Abbreviate</td> 
   <td>abbreviates a string using ellipsis or another given String</td> 
   <td>使用省略号或另一个给定的String缩写一个字符串</td> 
  </tr> 
  <tr> 
   <td>Difference</td> 
   <td>compares Strings and reports on their differences</td> 
   <td>比较字符串并报告其差异</td> 
  </tr> 
  <tr> 
   <td>LevenshteinDistance</td> 
   <td>the number of changes needed to change one String into another</td> 
   <td>将一个String转换为另一个String所需的更改次数</td> 
  </tr> 
 </tbody> 
</table>