String, StringBuffer, and StringBuilder

• String objects are immutable, and String reference variables are not.
• If you create a new String without assigning it, it will be lost to your program.
• If you redirect a String reference to a new String, the old String can be lost.
• String methods use zero-based indexes, except for the second argument of substring().
• The String class is final—its methods can't be overridden.
• When the JVM finds a String literal, it is added to the String literal pool.
• Strings have a method: length(); arrays have an attribute named length.
• The StringBuffer's API is the same as the new StringBuilder's API, except that StringBuilder's methods are not synchronized for thread safety.
• StringBuilder methods should run faster than StringBuffer methods.
• All of the following bullets apply to both StringBuffer and StringBuilder:
• They are mutable—they can change without creating a new object.
• StringBuffer methods act on the invoking object, and objects can change without an explicit assignment in the statement.
• StringBuffer equals() is not overridden; it doesn't compare values.
• Remember that chained methods are evaluated from left to right.
• String methods to remember: charAt(), concat(), equalsIgnoreCase(), length(), replace(), substring(), toLowerCase(), toString(), toUpperCase(), and trim().
• StringBuffer methods to remember: append(), delete(), insert(), reverse(), and toString().