关于java:isEmpty-和-isBlank-的用法区别至少一半的人答不上来

兴许你两个都不晓得, 兴许你除了 isEmpty/isNotEmpty/isNotBlank/isBlank 外, 并不知道还有 isAnyEmpty/isNoneEmpty/isAnyBlank/isNoneBlank 的存在, come on , 让咱们一起来摸索 org.apache.commons.lang3.StringUtils; 这个工具类。

isEmpty 系列

StringUtils.isEmpty()

是否为空. 能够看到 ” ” 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) {

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()

是否蕴含任何真空值 (蕴含空格或空值)

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()

是否全副都不蕴含空值或空格

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 的其余办法

能够参考官网的文档, 外面有具体的形容, 有些办法还是很好用的。

https://commons.apache.org/pr…

文章起源：https://sourl.cn/dRpJ6b