Many programs deal with character strings so here we give a brief
introduction to the String
class in the core Java language. Although strings in Java are class
objects, in several ways they act like primitive types.
Note: You don't need to understand
the concepts of classes and objects yet to use Java strings. In
later chapters we discuss more details of the String
class makes creation and handling of strings quite easy and straightforward.
While one could create arrays of char
values, you will find it much simpler to use Java strings in most
As with other classes, you can create an instance
of a string with the new
operator but to make life simpler, it is not required. So either
of the following declarations will work:
str= new String("A string");
str1 = " and another string";
You can append one string to another with a simple "+"
operation (which is the only case in Java of overloading an operator,
that is, redefining its operation according to the type of operands).
str2 = str + str1;
which results in str2
string and another string";
A very useful capability of the "+"
operator allows for default conversion of primitive type values
to strings. Whenever you "add" a primitive type value,
such as an int
value, to a string, the primitive value converts to a String
type and appends to the string. For example, this code
str1= "x = ";
int i = 5;
String str2 = str1 + 5;
results in str2
= 5". (This also works with boolean
type values, resulting in the strings "true"
class offers a large number of methods for accessing and manipulating
the characters in the string, but we will discuss these futher in
References & Web
Latest update: Oct. 14, 2004