Java技术-isEmpty 和 isBlank 的用法区别

水深无声 2024-02-05 21:20 11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, 他们都是org.apache.commons.lang3.StringUtils;这个工具类中的方法

### **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

源码分析：

/**
 *
 * 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;
 }

针对源码的分析，只可以看到对字符串的null判断和长度是否为0进行判断，例如带有空格的空字符串，长度是不为0的并且不为空，所以是可以通过的。

#### **StringUtils.isNotEmpty()** ####

> 相当于不为空 , **= !isEmpty()**

源码分析：

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

源码分析：

/**
         * @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. * * <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

/**
 * 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

/**
 * 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, “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的其他方法** ###

![91eaf1813d1b405bbb9270ee2cf6e59b.png][]

![b8ba9c13a0b24768af35e3d90a2c775c.png][]

![e1e73b624aeb49aeb072ea13891a167b.png][]

![345bfaaa2e614285b27271485ffad96f.png][] 也可以去[StringUtils (Apache Commons Lang 3.14.0 API)][StringUtils _Apache Commons Lang 3.14.0 API]去查看一下其他的用法。

[91eaf1813d1b405bbb9270ee2cf6e59b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/70d1764f5d08434a800508e774c8077d.png
[b8ba9c13a0b24768af35e3d90a2c775c.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/5ecf974880b14bde96d646f71cb3d398.png
[e1e73b624aeb49aeb072ea13891a167b.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/14721227f9af4bab88f4dad3a1d1d00a.png
[345bfaaa2e614285b27271485ffad96f.png]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/30/e9df637be0e848f98e5112b1eac802f5.png
[StringUtils _Apache Commons Lang 3.14.0 API]: https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html