Example: the String class
¥The String class is built-in to Java, just like Object.
¥Finger Exercise: evaluate
ÐString s = "Corky";
ÐObject o = s;
Ðo
¥o == s
¥String t = "Cork" + "yÓ;
¥t == s
¥s.length()
¥o = null;
¥o.length()

¥Morals:
Ðmultiple copies of the same String may exist; do not use == to test String equality.
ÐDo not use null to represent legitimate data values.