Java Reference
In-Depth Information
Figure 3.5
Sample outputs of the RandomLoop program.
The for Loop
A for loop is a repetition control structure that allows you to efficiently write a
loop that needs to execute a specific number of times. The syntax of a for loop is:
for( initialization ; Boolean_expression ; update )
{
//Statements
}
Here is the flow of control in a for loop:
1.
The initialization step is executed first, and only once. This step allows
you to declare and initialize any loop control variables. You are not
required to put a statement here, as long as a semicolon appears.
2.
Next, the Boolean expression is evaluated. If it is true, the body of the
loop is executed. If it is false, the body of the loop does not execute and
flow of control jumps to the next statement past the for loop.
3.
After the body of the for loop executes, the flow of control jumps back
up to the update statement. This statement allows you to update any
loop control variables. This statement can be left blank, as long as a
semicolon appears after the Boolean expression.
4.
The Boolean expression is now evaluated again. If it is true, the loop
executes and the process repeats itself (body of loop, then update step,
then Boolean expression). After the Boolean expression is false, the for
loop terminates.
Let's go through an example to demonstrate the preceding steps. Consider
the following for loop:
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