Lists, Logic, and Loops - Java 6 - page 98

for Loops
A for loop is used to repeat a statement until a condition is met. Although for loops fre-
quently are used for simple iteration in which a statement is repeated a certain number of
times, for loops can be used for just about any kind of loop.

The for loop in Java looks roughly like the following:

for ( initialization ; test ; increment ) {
statement ;

}

The start of the for loop has three parts:

initialization is an expression that initializes the start of the loop. If you have a
loop index, this expression might declare and initialize it, such as int i = 0 .
Variables that you declare in this part of the for loop are local to the loop itself;
they cease to exist after the loop is finished executing. You can initialize more than
one variable in this section by separating each expression with a comma. The state-
ment int i = 0, int j = 10 in this section would declare the variables i and j ,
and both would be local to the loop.

n

test is the test that occurs before each pass of the loop. The test must be a
Boolean expression or a function that returns a boolean value, such as i < 10 . If
the test is true , the loop executes. When the test is false , the loop stops execut-
ing.

n

increment is any expression or function call. Commonly, the increment is used to
change the value of the loop index to bring the state of the loop closer to returning
false and stopping the loop. The increment takes place after each pass of the loop.
Similar to the initialization section, you can put more than one expression in
this section by separating each expression with a comma.

n

The statement part of the for loop is the statement that is executed each time the loop
iterates. As with if , you can include either a single statement or a block statement. The
previous example used a block because that is more common. The following example is
a for loop that sets all slots of a String array to the value Mr. :

String[] salutation = new String[10];
int i; // the loop index variable

for (i = 0; i < salutation.length; i++)
salutation[i] = “Mr.”;

In this example, the variable i serves as a loop index; it counts the number of times the
loop has been executed. Before each trip through the loop, the index value is compared