Control Statements
programming language uses control statements to cause the flow of execution to
advance and branch based on changes to the state of a program. Java's program
control statements can be put into the following categories: selection, iteration, and
jump. Selection statements allow your program to choose different paths of execution based
upon the outcome of an expression or the state of a variable. Iteration statements enable
program execution to repeat one or more statements (that is, iteration statements form
loops). Jump statements allow your program to execute in a nonlinear fashion. All of Java's
control statements are examined here.
Java's Selection Statements
Java supports two selection statements: if and switch. These statements allow you to control the
flow of your program's execution based upon conditions known only during run time. You will
be pleasantly surprised by the power and flexibility contained in these two statements.
The if statement was introduced in Chapter 2. It is examined in detail here. The if statement
is Java's conditional branch statement. It can be used to route program execution through
two different paths. Here is the general form of the if statement:
if (condition) statement1;
else statement2;
Here, each statement may be a single statement or a compound statement enclosed in curly
braces (that is, a block). The condition is any expression that returns a boolean value. The else
clause is optional.
The if works like this: If the condition is true, then statement1 is executed. Otherwise,
statement2 (if it exists) is executed. In no case will both statements be executed. For example,
consider the following:
int a, b;
// ...
if(a < b) a = 0;
else b = 0;
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