String manipulation tools

package com.codebase.util;

/**
 * @describe: String manipulation tool class
 * @author:houkai
 * @Date: 2018/4/4 11:00
 */
 public class StringUtil { 

    /**
      * Whether the string is empty, including blank
      * @param str
 * @return
 */
 public static boolean isNullOrEmpty(String str){
         return null != str && 0 != str.trim().length() ? false : true ;              
    }

    /**
      * Determine if it is empty
      * @param str
 * @return
 */
 public static boolean isEmpty(String str){
         if (str== null || "" .equals(str.trim())){
             return true ;              
        }else{
            return false;
        }
    }

    /**
      * Check if the string is blank: null, empty string "" character.
     * StringUtil.isBlank(null) = true
      * StringUtil.isBlank("") = true
      * StringUtil.isBlank(" ") = true
      * StringUtil.isBlank("bob") = false
      * StringUtil.isBlank(" bob ") = false
      * @param str String to check for
      * @return true if blank
      */
 public static boolean isBlank(String str) {
         int length;
         if ((str == null ) || ((length = str. length()) == 0 )) {
             return true ;    
        }
        for (int i = 0; i < length; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return false;
            }
        }
        return true;
    }

    /**
      * Check if the string is not whitespace: null, the empty string "", or just whitespace characters.
     * StringUtil.isBlank(null) = false
      * StringUtil.isBlank("") = false
      * StringUtil.isBlank(" ") = false
      * StringUtil.isBlank("bob") = true
      * StringUtil.isBlank(" bob ") = true
      * @param str String to check for
      * @return true if blank
      */
 public static boolean isNotBlank(String str) {
         int length;
         if ((str == null ) || ((length = str. length()) == 0 )) {
             return false ;    
        }
        for (int i = 0; i < length; i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return true;
            }
        }
        return false;
    }
}