Programming and Problem Solving with Java

(^448) | Exceptions and Additional Control Structures

Guidelines for Choosing a Looping Statement

Here are some guidelines to help you decide when to use each of the three looping statements

(while,do, and for):

1.If the loop is a simple count-controlled loop, the forstatement is a natural

choice. Concentrating the three loop control actions—initialize, test, and

increment/decrement—into one location (the heading of the forstatement)

reduces the chances that you will forget to include one of them.

2.If the loop is an event-controlled loop whose body should execute at least once,

a dostatement is appropriate.

3.If the loop is an event-controlled loop and nothing is known about the first exe-

cution, use a whilestatement.

4.When in doubt, use a whilestatement.

9.3 Additional Java Operators

Java offers a rich, sometimes bewildering, array of operators that allow you to manipulate val-

ues of the primitive data types. Operators you have learned about so far include the assign-

ment operator (=), the arithmetic operators (+,-,*,/,%), the increment and decrement operators

(++,--), the relational operators (==,!=,<,<=,>,>=), the string concatenation operator (+), and

the conditional (short-circuit evaluation) logical operators (!,&&,||). In certain cases, a pair

of parentheses is also considered to be an operator—namely, the type cast operator,

y = (float)someInt;

Java also has many specialized operators that are seldom found in other programming

languages. Table 9.1 lists these additional operators. As you inspect the table, don’t panic—

a quick scan will do.

The operators in Table 9.1, along with those you already know, comprise all of the Java

operators.

Assignment Operators and Assignment Expressions

Java has several assignment operators. The equals sign (=) is the basic assignment operator.

When combined with its two operands, it forms anassignment expression(notan assignment

statement). Every assignment expression has avalueand aside effect—namely, that

the value is stored into the variable denoted by the left side of the expression. For

example, the expression

delta = 2 * 12

has the value 24 and the side effect of storing this value into delta.

Assignment expression A

Java expression with (1) a value

and (2) the side effect of storing

the expression value into a

memory location