flink-instrumentation/workspace/flink-1.4.1-instrumented/flink-1.4.1/flink-core/src/main/java/org/apache/flink/util/StringUtils.java
/**
	 * Checks if the string is null, empty, or contains only whitespace characters.
	 * A whitespace character is defined via {@link Character#isWhitespace(char)}.
	 * 
	 * @param str The string to check
	 * @return True, if the string is null or blank, false otherwise.
	 */
Checks if the string is null, empty, or contains only whitespace characters.
A whitespace character is defined via  Character#isWhitespace(char).

@param str The string to check
@return True, if the string is null or blank, false otherwise.
Checks if the string is null empty or contains only whitespace characters . A whitespace character is defined via Character#isWhitespace ( char ) . @param str The string to check @return True if the string is null or blank false otherwise .
public static boolean isNullOrWhitespaceOnly(String str) {
		if (str == null || str.length() == 0) {
			return true;
		}
		final int len = str.length();
		for (int i = 0; i < len; i++) {
			if (!Character.isWhitespace(str.charAt(i))) {
				return false;
			}
		}
		return true;
	}
public static boolean isNullOrWhitespaceOnly ( String str ) { if ( str == null || str . length ( ) == 0 ) { return true ; } final int len = str . length ( ) ; for ( int i = 0 ; i < len ; i ++ ) { if ( ! Character . isWhitespace ( str . charAt ( i ) ) ) { return false ; } } return true ; }
Checks if the string is null, empty, or contains only whitespace characters.
Checks if the string is null empty or contains only whitespace characters .