public static boolean isBlank(String str) {

        if (str == null || str.length() == 0) {
            return true;
        }
        for (int i = 0; i < str.length(); i++) {
            if (!Character.isWhitespace(str.charAt(i))) {
                return false;
            }
        }
        return true;
    }
is null or its length is 0 or it is made by space
<p/>
<pre>
isBlank(null) = true;
isBlank(&quot;&quot;) = true;
isBlank(&quot;  &quot;) = true;
isBlank(&quot;a&quot;) = false;
isBlank(&quot;a &quot;) = false;
isBlank(&quot; a&quot;) = false;
isBlank(&quot;a b&quot;) = false;
</pre>

@param str str
@return if string is null or its size is 0 or it is made by space, return
true, else return false.
app/src/main/java/coder/prettygirls/util/StringUtil.java