Loops

For loops

In Java, you can use for loops to execute a block of code repeatedly for a fixed number of times. Here's an example:

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

In the above example, we use a for loop to print the numbers from 1 to 5. The loop starts with an initial value of i equal to 1, and executes as long as i is less than or equal to 5. The loop increments i by 1 after each iteration, using the i++ shorthand for i = i + 1.

You can also use it for loops with arrays, like this:

public class ArrayLoopExample {
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5};

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

In the above example, we use a for loop to iterate over an array of numbers. The loop starts with an initial value of i equal to 0, and executes as long as i is less than the length of the numbers array. The loop increments i by 1 after each iteration.

While loops

In Java, you can use while loops to execute a block of code repeatedly as long as a certain condition is true. Here's an example:

public class WhileLoopExample {
    public static void main(String[] args) {
        int i = 1;

        while (i <= 5) {
            System.out.println(i);
            i++;
        }
    }
}

In the above example, we use a while loop to print the numbers from 1 to 5. The loop starts with an initial value of i equal to 1, and executes as long as i is less than or equal to 5. The loop increments i by 1 after each iteration.

You can also use while loops with boolean variables, like this:

public class BooleanLoopExample {
    public static void main(String[] args) {
        boolean keepGoing = true;
        int i = 1;

        while (keepGoing) {
            System.out.println(i);

            if (i == 5) {
                keepGoing = false;
            }

            i++;
        }
    }
}

In the above example, we use a while loop to print the numbers from 1 to 5, but we use a boolean variable keepGoing to control the loop instead of a numeric condition. The loop starts with an initial value of keepGoing equal to true, and executes as long as keepGoing is true. The loop sets keepGoing to false when i equals 5, causing the loop to exit.

Do-while loops

In Java, you can use do-while loops to execute a block of code repeatedly at least once, and then as long as a certain condition is true. Here's an example:

public class DoWhileLoopExample {
    public static void main(String[] args) {
        int i = 1;

        do {
            System.out.println(i);
            i++;
        } while (i <= 5);
    }
}

In the above example, we use a do-while loop to print the numbers from 1 to 5. The loop starts by executing the block of code once and then continues to execute as long as i is less than or equal to 5. The loop increments i by 1 after each iteration.

Do-while loops are useful when you need to execute a block of code at least once, regardless of the condition.

That's an overview of loops, while loops, and do-while loops in Java.