[java] StringUtils.isBlank() vs String.isEmpty()

I ran into some code that has the following:

String foo = getvalue("foo");
if (StringUtils.isBlank(foo))
    doStuff();
else
    doOtherStuff();

This appears to be functionally equivalent to the following:

String foo = getvalue("foo");
if (foo.isEmpty())
    doStuff();
else
    doOtherStuff();

Is a difference between the two (org.apache.commons.lang3.StringUtils.isBlank and java.lang.String.isEmpty)?

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() 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.

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;
}

I am answering this because it's the top result in Google for "String isBlank() Method".

If you are using Java 11 or above, you can use the String class isBlank() method. This method does the same thing as Apache Commons StringUtils class.

I have written a small post on this method examples, read it here.

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

StringUtils.isBlank also returns true for just whitespace:

isBlank(String str)

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

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

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

will throw a NullPointerException if foo is null.

The bottom line is :

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

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

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

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