### Question:
B2StringUtil { static boolean isEmpty(String str) { if (str == null) { return true; } str = str.trim(); return (str.length() == 0); } B2StringUtil(); static String percentEncode(String s); static String percentDecode(String s); static int decimalSubstringToInt(String s, int startIndex, int endIndex); static boolean decimalNumberInRange(String str, int offset, int length,
                                               int minInclusive, int maxInclusive); static String join(String delimiter, Object[] objects); static byte [] getUtf8Bytes(String str); static String toHexString(byte[] b); static String underscoresToCamelCase(String orig, boolean capitalizeFirstLetter); static boolean startsWithIgnoreCase(String all, String possiblePrefix); static final String UTF8; }### Answer:
@Test public void testIsEmpty() { assertTrue(isEmpty(null)); assertTrue(isEmpty("")); assertTrue(!isEmpty("foo")); }