Java For Loop Example

You can use loops in programming to carry out a set of instructions repeatedly until a certain condition is met.

There are three types of loops in Java:

• for loop.
• while loop.
• do...while loop.

In this article, we'll focus on the for loop, its syntax, and some examples to help you use it in your code.

The for loop is mostly used when you know the number of times a loop is expected to run before stopping.

Java For Loop Syntax

Here's what the syntax of for loop in Java looks like:

for (initialization; condition; increment/decrement) {
   // code to be executed
}

In the syntax above:

• initialization denotes an initial variable declared at the starting point of the loop, usually an integer.
• condition denotes the number of times the loop is supposed to run.
• increment/decrement increases/decreases the value of the initial variable every time the loop runs. As the increment/decrement happens, the variable's value tends towards the specified condition.

Java For Loop Example

In this section, you'll see some practical code examples of the for loop in Java:

Java For Loop Example #1

class ForLoopExample {
    public static void main(String[] args) {
        for(int x = 1; x <=10; x++) {
            System.out.println(x);
            // 1
            // 2
            // 3
            // 4
            // 5
            // 6
            // 7
            // 8
            // 9
            // 10
        }
    }
}

In the code above, we used a for loop to print numbers from 1 to 10.

But how does it work? Take a look the conditions given: (int x = 1; x <=10; x++).

At first, x was set to 1.

The second condition —  x <=10 — denotes that the loop is expected to run as long the value of x is less than or equal to 10.

The third condition — x++ — increases the value of x every time the loop runs.

The loop then prints the value of x every time it is increased.

Java For Loop Example #2

In this example, you'll learn how to print all the values stored in an array.

class ForLoopExample {
    public static void main(String[] args) {
        int[] oddNumbers = {1, 3, 5, 7};
        for (int i = 0; i < oddNumbers.length; i++) {
          System.out.println(oddNumbers[i]);
          // 1
          // 3
          // 5
          // 7
        }
    }
}

The conditions in the code above are a bit different compared to the first example, but the logic is the same.

i has an initial value of 0 because the index of an array in Java starts at 0. The first element is 0, the second is 1, and so on.

i < oddNumbers.length means that the code is expected to run as long as the value of i is less than the length of the array. The length of the array is 4 so that means i < 4.

i++ increases the value of i every time the code runs until the condition i < 4 is false.

The code prints 1, 3, 5, 7 in the console.

Without a loop, you'd achieve the same result by doing something like this:

class ForLoopExample {
    public static void main(String[] args) {
        int[] oddNumbers = {1, 3, 5, 7};
          System.out.println(oddNumbers[0]); // 1
          System.out.println(oddNumbers[1]); // 3
          System.out.println(oddNumbers[2]); // 5
          System.out.println(oddNumbers[3]); // 7
    }
}

Imagine having an array with 100 elements. You'd have to type one hundred println methods to print all of them.

With a loop, you can achieve that with a line of code.

Summary

In this article, we talked about the for loop in Java. We use loops to execute code repeatedly until a condition is met.

We first saw the syntax for using the for loop in Java. We then looked at some practical code examples showing how the loop works.

Happy coding!