Arrays and Strings - Beginning Java - page 200

• WHAT YOU LEARNED IN THIS CHAPTER

TOPIC CONCEPT

Using an Array You use an array to hold multiple values of the same type, identified through a single variable

name.

Accessing Array
Elements

You reference an individual element of an array by using an index value of type int . The index
value for an array element is the offset of that element from the first element in the array, so the in-
dex of the first element is 0.

Using Array Ele-
ments

An array element can be used in the same way as a single variable of the same type.

The Number of
Array Elements

You can obtain the number of elements in an array by using the length member of the array object.

Arrays of Arrays An array element can also contain an array, so you can define arrays of arrays, or arrays of arrays of
arrays, and so on.

String Objects A String object stores a fixed character string that cannot be changed. However, you can assign a

given String variable to a different String object.

String Length You can obtain the number of characters stored in a String object by using the length() method

for the object.

String Class
Methods

The String class provides methods for joining, searching, and modifying strings — the modifica-
tions being achieved by creating a new String object.

Mutable Strings StringBuffer and StringBuilder objects can store a string of characters that you can modify.

StringBuffer and StringBuilder objects support the same set of operations. StringBuffer ob-
jects are safe when accessed by multiple threads of execution whereas StringBuilder object are
not.

StringBuffer
and
StringBuilder
Objects

Length and Capa-
city of a
StringBuffer
object

You can get the number of characters stored in a StringBuffer object by calling its length()
method, and you can find out the current maximum number of characters it can store by using its
capacity() method. You can change both the length and the capacity for a StringBuffer object.

Creating a String
Object from a
StringBuffer
object

You can create a String object from a StringBuffer object by using the toString() method of
the StringBuffer object.