Strings and Regular Expressions - The Java Programming Language - page 489

This code creates just one StringBuilder object to hold the construction,
appends stuff to it, and then uses toString to create a String from the
result.

To build and modify a string, you probably want to use the StringBuilder
class. StringBuilder provides the following constructors:

public StringBuilder()

Constructs a StringBuilder with an initial value of "" (an empty
string) and a capacity of 16.

public StringBuilder(int capacity)

Constructs a StringBuilder with an initial value of "" and the
given capacity.

public StringBuilder(String str)

Constructs a StringBuilder with an initial value copied from
str .

public StringBuilder(CharSequence seq)

Constructs a StringBuilder with an initial value copied from
seq .

StringBuilder is similar to String , and it supports many methods that
have the same names and contracts as some String methods indexOf ,
lastIndexof , replace , substring . However, StringBuilder does not extend
String nor

vice versa. They are independent implementations of

CharSequence .