public static boolean isBlank(CharSequence cs) {
        int strLen;
        if (cs == null || (strLen = cs.length()) == 0) {
            return true;
        }
        for (int i = 0; i < strLen; i++) {
            if (Character.isWhitespace(cs.charAt(i)) == false) {
                return false;
            }
        }
        return true;
    }
<p>Checks if a CharSequence is whitespace, empty ("") or null.</p>

<pre>
StringUtils.isBlank(null)      = true
StringUtils.isBlank("")        = true
StringUtils.isBlank(" ")       = true
StringUtils.isBlank("bob")     = false
StringUtils.isBlank("  bob  ") = false
</pre>

@param cs  the CharSequence to check, may be null
@return {@code true} if the CharSequence is null, empty or whitespace
@since 2.0
@since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)
android/android_framework/base/src/main/java/lang3/StringUtils.java