Literals of types char and String may contain any Unicode (UTF-16) characters. If your editor and file system allow it, you can use such characters directly in your code. If not, you can use a “Unicode escape” such as ‘\u0108′ (capital C with circumflex), or “S\u00ED Se\u00F1or” (Sí Señor in Spanish). Always use ‘single quotes’ for char literals and “double quotes” for String literals. Unicode escape sequences may be used elsewhere in a program (such as in field names, for example), not just in char or String literals.
The Java programming language also supports a few special escape sequences for char and String literals:
\b (backspace), \t (tab), \n (line feed), \f (form feed), \r (carriage return), \” (double quote), \’ (single quote), and \\ (backslash).
There’s also a special null literal that can be used as a value for any reference type. null may be assigned to any variable, except variables of primitive types. There’s little you can do with a null value beyond testing for its presence. Therefore, null is often used in programs as a marker to indicate that some object is unavailable.
Finally, there’s also a special kind of literal called a class literal, formed by taking a type name and appending “.class”; for example, String.class. This refers to the object (of type Class) that represents the type itself.