Introduction to Java For Loop with Examples and Syntax

Introduce Java For Loop and give examples

The for loop in Java is a control flow statement that allows code to be executed repeatedly based on a given boolean condition. It is commonly used when the number of iterations is known beforehand. The for loop consists of three main parts: initialization, condition, and increment/decrement.

Syntax of a For Loop

for (initialization; condition; update) {
    // Code to be executed in each iteration
}

• Initialization: This is executed once at the beginning of the loop. It is typically used to declare and initialize loop control variables.
• Condition: This is evaluated before each iteration. If it evaluates to true, the loop body is executed. If it evaluates to false, the loop terminates.
• Update: This is executed at the end of each iteration. It is typically used to update the loop control variable.

Example 1: Basic For Loop

Here’s a simple example that prints the numbers from 1 to 5:

public class ForLoopExample {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            System.out.println(i);
        }
    }
}

Output:

1
2
3
4
5

Example 2: For Loop with an Array

In this example, we will use a for loop to iterate over an array of integers and print each element:

public class ArrayForLoop {
    public static void main(String[] args) {
        int[] numbers = {10, 20, 30, 40, 50};

        for (int i = 0; i < numbers.length; i++) {
            System.out.println("Element at index " + i + ": " + numbers[i]);
        }
    }
}

Output:

Element at index 0: 10
Element at index 1: 20
Element at index 2: 30
Element at index 3: 40
Element at index 4: 50

Example 3: Nested For Loop

You can also nest for loops. Here’s an example that prints a multiplication table:

public class NestedForLoop {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            for (int j = 1; j <= 5; j++) {
                System.out.print(i * j + "\t");
            }
            System.out.println(); // Move to the next line after each row
        }
    }
}

Output:

1	2	3	4	5	
2	4	6	8	10	
3	6	9	12	15	
4	8	12	16	20	
5	10	15	20	25	

Example 4: For Loop with Decrement

You can also use a for loop to count downwards. Here’s an example that counts down from 5 to 1:

public class Countdown {
    public static void main(String[] args) {
        for (int i = 5; i >= 1; i--) {
            System.out.println(i);
        }
    }
}

Output:

5
4
3
2
1

Conclusion

The for loop is a powerful and flexible control structure in Java that allows for efficient iteration over a range of values, arrays, or collections. By understanding its syntax and structure, you can effectively use it in various programming scenarios.