Some useful classes - Multimedia Introduction to Programming Using Java - page 174

System.out.print("The square of 25 is: ");
System.out.println(25 * 25);

5.2.2 The basics of String manipulation

A string literal has a class-type: String . Since String is a class, and not a prim-
itive type, the literal is contained in an instance of String , for example,

Activity
5-3.2

a0

String

"xy z"

String variables can be declared and assigned values. Class String is special in
that there is no need to use a new-expression (although it can be used); just use
a string literal instead. For example, execution of these statements:

String s= "NO!"
String t;
t= "Yes.";

result in these variables and String folders:

a6

a7

s 6

String

String

t 7 "NO!" "Yes."

We now describe various operations on strings and also introduce notation
for talking about strings.

Catenation of Strings
To catenate two strings means to join their characters into a single string.
The word concatenation is often used for this operation; we prefer the shorter
word, catenation . Java uses the binary infix addition symbol + for catenation:

Activity
5-3.3

"abc" + "xyz" evaluates to "abcxyz"

Of course, if both operands of + have numerical types, the symbol denotes addi-
tion, but if at least one operand is a String , the symbol denotes catenation.
If one of the operands of a catenation is a value of some primitive type, like
int or boolean , it is converted to a String . For example, the expression

2.5 + ", 62 "

evaluates to a String object whose value is " 2.5, 62 " .