isEmpty 和 isBlank 的用法区别

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
/**<br> * @param css  the CharSequences to check, may be null or empty  * <br> * @return {@code true} if any of the CharSequences are empty or null  * <br> * @since 3.2  <br> */
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

/**<br> * <p>Checks if none of the CharSequences are empty ("") or null.</p> <br> * <pre> StringUtils.isNoneEmpty(null) = false  <br> *       StringUtils.isNoneEmpty(null, "foo") = false  <br> *       StringUtils.isNoneEmpty("", "bar") = false <br> *       StringUtils.isNoneEmpty("bob", "") = false   <br> *       StringUtils.isNoneEmpty("  bob  ", null)  = false    <br> *       StringUtils.isNoneEmpty(" ", "bar")       = true   <br> *       StringUtils.isNoneEmpty("foo", "bar")     = true   <br> * </pre>  <br> * @param css  the CharSequences to check, may be null or empty   <br> * @return {@code true} if none of the CharSequences are empty or null  <br> * @since 3.2  <br> */

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
/**<br> * <p>Checks if none of the CharSequences are blank ("") or null and whitespace only..</p>  * <br> * @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  * <br> * @since 3.2  <br>*/
public static boolean isNoneBlank(final CharSequence... css) {
  return !isAnyBlank(css);
}