Java Programming Language (Loops: for loop)

#java #programming #beginners #tutorial

for loop

for (initialExpression; testExpression; updateExpression) {...}

for loop has the same concept of general loop. In while loop we needed to manually update the iteration inside the code block. However, in for loop, it automatically iterates through the loop.

For example, I want to find the sum of the numbers 1 to 100.

public class Loops {
    public static void main(String[] args) {
        int sum = 0;
        for (int i = 1; i <= 100; i++) {
            sum += i;
        }
        System.out.println(sum);
    }
}

Step01: Using for we initialise a loop

Step02: Inside the loop parenthesis, initialExpression is int i = 1, declaring the iteration variable

Step03: testExpression is i <= 100, returns a boolean value to check whether it is true or false

Step04: updateExpression is i++, updating the iteration variable every time the loop repeats

Step05: Code inside the loop block will execute until the loop terminates

Step06: Once the iteration variable i becomes 101, the testExpression becomes false and the loop will terminate
Output

for...each loop

for (dataType item: array) {...}

for...each loop is actually performed in an array to iterate through the elements inside it. So, I recommend you to take a look at the Arrays section before learning for...each loop.

An example of for...each loop is given below,

public class Loops {
    public static void main(String[] args) {
        int[] numbers = {98, 92, 98, 85};
        for (int number: numbers) {
            System.out.println(number);
        }
    }
}

Step01: Using for we initialise the loop

Step02: Inside the loop parenthesis, we declare the data type of the elements inside the array. In this case int

Step03: Then we declare a new variable number for each elements. In every iteration, the values inside the array will be assigned to this variable one by one. For example in first iteration number = 98, second iteration number = 92 and so on.

Step04: Then we pass the array which we want to iterate through separating by :

Step05: The loop will repeat n number of times, where n is the length of the array
Output