Stringutils. isBlank() vs String. isEmpty()

The accepted answer from @arshajii is totally correct. However just being more explicit by saying below,

StringUtils.isBlank()

 StringUtils.isBlank(null)      = true
 StringUtils.isBlank("")        = true  
 StringUtils.isBlank(" ")       = true  
 StringUtils.isBlank("bob")     = false  
 StringUtils.isBlank("  bob  ") = false

StringUtils.isEmpty

 StringUtils.isEmpty(null)      = true
 StringUtils.isEmpty("")        = true  
 StringUtils.isEmpty(" ")       = false  
 StringUtils.isEmpty("bob")     = false  
 StringUtils.isEmpty("  bob  ") = false

StringUtils isEmpty = String isEmpty checks + checks for null.

StringUtils isBlank = StringUtils isEmpty checks + checks if the text contains only whitespace character(s).

Useful links for further investigation:

• StringUtils isBlank documentation
• StringUtils isEmpty documentation
• String isEmpty documentation

StringUtils.isBlank() will also check for null, whereas this:

String foo = getvalue("foo");
if (foo.isEmpty())

will throw a NullPointerException if foo is null.

StringUtils.isBlank also returns true for just whitespace:

isBlank(String str)

Checks if a String is whitespace, empty ("") or null.

StringUtils.isBlank(foo) will perform a null check for you. If you perform foo.isEmpty() and foo is null, you will raise a NullPointerException.

The only difference between isBlank() and isEmpty() is:

StringUtils.isBlank(" ")       = true //compared string value has space and considered as blank

StringUtils.isEmpty(" ")       = false //compared string value has space and not considered as empty

StringUtils.isBlank() returns true for blanks(just whitespaces)and for null String as well. Actually it trims the Char sequences and then performs check.

StringUtils.isEmpty() returns true when there is no charsequence in the String parameter or when String parameter is null. Difference is that isEmpty() returns false if String parameter contains just whiltespaces. It considers whitespaces as a state of being non empty.

Instead of using third party lib, use Java 11 isBlank()

    String str1 = "";
    String str2 = "   ";
    Character ch = '\u0020';
    String str3 =ch+" "+ch;

    System.out.println(str1.isEmpty()); //true
    System.out.println(str2.isEmpty()); //false
    System.out.println(str3.isEmpty()); //false            

    System.out.println(str1.isBlank()); //true
    System.out.println(str2.isBlank()); //true
    System.out.println(str3.isBlank()); //true

public static boolean isEmpty(String ptext) {
 return ptext == null || ptext.trim().length() == 0;
}

public static boolean isBlank(String ptext) {
 return ptext == null || ptext.trim().length() == 0;
}

Both have the same code how will isBlank handle white spaces probably you meant isBlankString this has the code for handling whitespaces.

public static boolean isBlankString( String pString ) {
 int strLength;
 if( pString == null || (strLength = pString.length()) == 0)
 return true;
 for(int i=0; i < strLength; i++)
 if(!Character.isWhitespace(pString.charAt(i)))
 return false;
 return false;
}

The bottom line is :

isEmpty take " " as a character but isBlank not. Rest both are same.