org.apache.commons.lang3.StringUtils类的isNotBlank和isEmpty方法
今天在做项目的时候遇到一个小bug,org.apache.commons.lang3.StringUtils类的isEmpty不能判断空字符串。
查询isEmpty方法的源码,可以发现isEmpty不能判断空字符串。
1 /** 2 * <p>Checks if a CharSequence is empty ("") or null.</p> 3 * 4 * <pre> 5 * StringUtils.isEmpty(null) = true 6 * StringUtils.isEmpty("") = true 7 * StringUtils.isEmpty(" ") = false 8 * StringUtils.isEmpty("bob") = false 9 * StringUtils.isEmpty(" bob ") = false 10 * </pre> 11 * 12 * <p>NOTE: This method changed in Lang version 2.0. 13 * It no longer trims the CharSequence. 14 * That functionality is available in isBlank().</p> 15 * 16 * @param cs the CharSequence to check, may be null 17 * @return {@code true} if the CharSequence is empty or null 18 * @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence) 19 */ 20 public static boolean isEmpty(final CharSequence cs) { 21 return cs == null || cs.length() == 0; 22 }
查询isNotBlank方法的源码,isNotBlank可以判断所有为空的情况。
1 /** 2 * <p>Checks if a CharSequence is whitespace, empty ("") or null.</p> 3 * 4 * <pre> 5 * StringUtils.isBlank(null) = true 6 * StringUtils.isBlank("") = true 7 * StringUtils.isBlank(" ") = true 8 * StringUtils.isBlank("bob") = false 9 * StringUtils.isBlank(" bob ") = false 10 * </pre> 11 * 12 * @param cs the CharSequence to check, may be null 13 * @return {@code true} if the CharSequence is null, empty or whitespace 14 * @since 2.0 15 * @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence) 16 */ 17 public static boolean isBlank(final CharSequence cs) { 18 int strLen; 19 if (cs == null || (strLen = cs.length()) == 0) { 20 return true; 21 } 22 for (int i = 0; i < strLen; i++) { 23 if (Character.isWhitespace(cs.charAt(i)) == false) { 24 return false; 25 } 26 } 27 return true; 28 } 29 30 /** 31 * <p>Checks if a CharSequence is not empty (""), not null and not whitespace only.</p> 32 * 33 * <pre> 34 * StringUtils.isNotBlank(null) = false 35 * StringUtils.isNotBlank("") = false 36 * StringUtils.isNotBlank(" ") = false 37 * StringUtils.isNotBlank("bob") = true 38 * StringUtils.isNotBlank(" bob ") = true 39 * </pre> 40 * 41 * @param cs the CharSequence to check, may be null 42 * @return {@code true} if the CharSequence is 43 * not empty and not null and not whitespace 44 * @since 2.0 45 * @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence) 46 */ 47 public static boolean isNotBlank(final CharSequence cs) { 48 return !isBlank(cs); 49 }
总结:当需要判断字符串为空时最好用org.apache.commons.lang3.isNotBlank方法。