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Trail: Learning the Java Language
Lesson: Language Basics

## The for Statement

> The for statement provides a compact way to iterate over a range of values. The general form of the `for` statement can be expressed like this:

> >     for (initialization; termination; increment) {
> >         statement
> >     }

> The `initialization` is an expression that initializes the loop-it's executed once at the beginning of the loop. The `termination` expression determines when to terminate the loop. This expression is evaluated at the top of each iteration of the loop. When the expression evaluates to `false`, the loop terminates. Finally, `increment` is an expression that gets invoked after each iteration through the loop. All these components are optional. In fact, to write an infinite loop, you omit all three expressions:

> >     for ( ; ; ) {    // infinite loop
> >         ...
> >     }

> Often `for` loops are used to iterate over the elements in an array, or the characters in a string. The following sample, `ForDemo`, uses a `for` statement to iterate over the elements of an array and print them:

> >     public class ForDemo {
> >         public static void main(String[] args) {
> >             int[] arrayOfInts = { 32, 87, 3, 589, 12, 1076,
> >                                   2000, 8, 622, 127 };

> >             for (int i = 0; i < arrayOfInts.length; i++) {
> >                 System.out.print(arrayOfInts[i] + " ");
> >             }
> >             System.out.println();
> >         }
> >     }

> The output of the program is: `32 87 3 589 12 1076 2000 8 622 127`.

> Note that you can declare a local variable within the initialization expression of a `for` loop. The scope of this variable extends from its declaration to the end of the block governed by the `for` statement so it can be used in the termination and increment expressions as well. If the variable that controls a `for` loop is not needed outside of the loop, it's best to declare the variable in the initialization expression. The names `i`, `j`, and `k` are often used to control `for` loops; declaring them within the `for` loop initialization expression limits their life-span and reduces errors.

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