Utils { public boolean isBlank(final 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))) { return false; } } return true; }  boolean isBlank(final CharSequence cs); boolean isNotBlank(final CharSequence cs); String trimToSize(String str, int maxStringLength); void sleep(int ms); void logIssue(String message, Throwable ex); String getApplicationName(Context context); String getVersionName(Context context); int getVersionCode(Context context); String getApplicationPackageName(Context context); @NonNull String getAndroidId(Context context); boolean isOnWifi(Context context);  }
@Test public void testIsBlank() { assertTrue(utils.isBlank("")); assertTrue(utils.isBlank(" ")); assertTrue(utils.isBlank(" ")); assertTrue(utils.isBlank(null)); assertTrue(utils.isBlank("\n")); assertFalse(utils.isBlank("test")); assertFalse(utils.isBlank(" test")); assertFalse(utils.isBlank(" test")); assertFalse(utils.isBlank("@")); assertFalse(utils.isBlank("~")); assertFalse(utils.isBlank("`")); assertFalse(utils.isBlank("\"")); }