isEmpty 和 isBlank 的用法区别，居然一半的人答不上来.....-轻识

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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) = trueStringUtils.isEmpty("") = trueStringUtils.isEmpty(" ") = falseStringUtils.isEmpty(“bob”) = falseStringUtils.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) = 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) = trueStringUtils.isBlank("") = trueStringUtils.isBlank(" ") = trueStringUtils.isBlank(“bob”) = falseStringUtils.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) = 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

     /**     * <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) = 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

   /**     * <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);    }