For-Loop

A major drawback of the while loop is that we can't specify an exact number of iterations and fully control the loop's execution. That's why the for loop exists, which provides us with all the tools for proper loop control and is also used when working with arrays and collections. It's a cool thing.

For Loop

The for loop is a control flow statement that allows you to repeatedly execute a block of code for a specified number of times. It is commonly used when you know the exact number of iterations or when iterating over a collection or array.

The syntax in for-loop in Java is as follows:

Main


              123
            
for (initialization; condition; update) {
    // code to be executed
}

If we go step by step, initially, we initialize a variable in a special section for it (we did the same for the while loop, only we did it outside the loop). Then we set the condition for when the loop should run (for example, as long as the variable is less than 10). After that, in the third section, we use an increment or decrement. Below is a flowchart and an explanation of the operation of each of the loop blocks:

Here's the breakdown of each part of the for loop:

Initialization: This is the initial setup executed only once at the beginning of the loop. Typically, you declare and initialize a loop control variable here. For example, int i = 0;
Condition: This is the condition checked before each iteration. If the condition is true, the loop body is executed. If the condition is false, the loop terminates. For example, i < 10;
Increment/Decrement Expression: This is the code executed after each iteration. Typically, you update the loop control variable here. For example, i++ (which is equivalent to i = i + 1);
Code Inside Loop: This is the block of code executed for each iteration of the loop. You can put any valid Java code inside the loop body.

Here's an example that demonstrates the usage of a for loop:

Main


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package com.example;

public class Main {
    public static void main(String[] args) {
        for (int i = 0; i < 10; i++) {
            System.out.println("Iteration: " + i);
        }
    }
}

In this example, the loop will execute 10 times. It starts with i initialized to 0, checks if i is less than 10, executes the loop body, and then updates i by incrementing it by 1. This process repeats until the condition becomes false.

It's worth noting that in this loop, we can use the variable we created. In our case, we output the variable i to display the iteration number on the screen.

This is very useful, especially when we need our variable i to be involved in the code.

Let's look at another example where we need to display only even numbers in the range from 1 to 30:

main


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package com.example;

public class Main {
    public static void main(String[] args) {
        for (int i = 0; i < 30; i++) { 
            if (i % 2 == 0) { // check if `i` is even 
                System.out.println(i);
            }
        }
    }
}

Great, in the code above, we used the variable i when checking the condition. In other words, i represents the numbers we are considering. Next, we check if the number i is even using the modulo operation (%). If the remainder of division by 2 is zero, then the number is even, meaning it is divisible by 2 without a remainder.

Also, pay attention to how we set the condition for i. The algorithm of our actions remains the same as it was, but in the loop condition, we limited i to a value of 30, as specified in the task.

Note

You can customize the initialization, condition, and update expressions according to your specific needs. The for loop provides a convenient way to control the iteration process and perform repetitive tasks efficiently.

1. How many iterations will be there?

2. How many times "i" will be displayed

Everything was clear?

Thanks for your feedback!

Section 3. Chapter 4

Java Basics

For-Loop

For Loop