Usage differences between isempty and isblank

First , Both methods use tool classes StringUtils The method inside , Are used to determine whether the string is empty

And this tool class is everywhere , Recommended Apache Of Not bound by the frame , The method is also complete

1）isEmpty

Determine whether the string is an empty string , As long as there is an arbitrary character （ Include white space characters ） It's not empty .

Look at isEmpty Source code of the method ：

public static boolean isEmpty(CharSequence cs) {
    return cs == null || cs.length() == 0;
}

This method only judges whether it is for null Or the length is 0.

signify , If user input "    " And so on , This method will not pass , The result is not empty .

If you want to verify, enter the following ：

Input content	Is it empty
"    "	no
""	yes
"Java Technology stack "	no

2、isBlank

Determine whether the string is an empty string , All white space characters are also empty .

Look at isBlank Source code of the method ：

public static boolean isBlank(CharSequence cs) {
    int strLen = length(cs);
    if (strLen == 0) {
        return true;
    } else {
        for(int i = 0; i < strLen; ++i) {
            if (!Character.isWhitespace(cs.charAt(i))) {
                return false;
            }
        }

        return true;
    }
}

The first 7 That's ok , As long as one character is not a blank character, it returns false, in other words , If all are white space characters, it returns true, That is, all white space characters are empty .

If you want to verify, enter the following ：

Input content	Is it empty
"    "	yes
""	yes
"Java Technology stack "	no

Now , If user input "    " And so on , This method also returns null , This is also what we expect in most business scenarios .