Basic "for" Statements

This section describes basic 'for' statement, which is a looping statement that executes the contained statement repeatedly with an initial logic, a looping condition, and an update logic.

"for" statements have 2 forms: basic "for" statements and enhanced "for" statements. Let's look at basic "for" statements in this tutorial first.

What Is Basic "for" Statement? - A basic "for" statement is a looping statement that executes the contained statement repeatedly with an initial logic, a looping condition, and an update logic.

Here is the syntax for a basic "for" statement.

```for (initial_logic; looping_condition; update_logic) contained_statement
```

When a basic "for" statement is executed, the flow of control can be described as:

Step 1. Run "initial_logic".

Step 2. Evaluate "looping_condition". If result is "false", end the "for" statement.

Step 3. Run "contained_statement".

Step 4. Run "update_logic".

Step 5. Go back to Step 2.

The contained statement can be empty, a simple single statement, or a complex statement block. Here is a sample program that shows you how to use basic "for" statements:

```/* BasicForStatementTest.java
*/
class BasicForStatementTest {
public static void main(String[] arg) {
java.io.PrintStream out = System.out;
int max = 20;
int sum = 0;

out.println("\"for\" statement with no contained statement:");
for (int i = 0; i < max; sum += ++i);
out.println("   Sum of 1 to 20: "+sum);
sum = 0;

out.println("\"for\" statement with a contained statement:");
for (int i = 0; i < max; i++) sum += i;
out.println("   Sum of 0 to 19: "+sum);

out.println("\"for\" statement with a contained statement block:");
for (int i = 3; i < max; i++) {
boolean isPrime = true;
for (int j = 2;  j <= i/2; j++) {
isPrime = i%j > 0;
if (!isPrime) break;
}
if (isPrime) out.println("   "+i+" is a prime number.");
}
}
}
```

If you compile and run the above program, you will see:

```herong> java BasicForStatementTest.java

"for" statement with no contained statement:
Sum of 1 to 20: 210

"for" statement with a contained statement:
Sum of 0 to 19: 190

"for" statement with a contained statement block:
3 is a prime number.
5 is a prime number.
7 is a prime number.
11 is a prime number.
13 is a prime number.
17 is a prime number.
19 is a prime number.
```