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) = 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) {

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()

是否蕴含任何真空值(蕴含空格或空值)

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()

是否全副都不蕴含空值或空格

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);}

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...



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