Java Tutorial Blog

How to Use for Loop in Java

//  by 

Looping is a programming concept that runs until the condition specified becomes false. The Loops in Java are responsible for repeating a block of code. It is a very useful programming feature since it provides feasibility in the code. There is no need to write the same code repeatedly since the looping concept is based on “Do More, Write Less”. Java supports three types of loops: “do-while”, “for”, and “while” loop. 

In this write-up, we will demonstrate the implementation of a for loop in Java.

How to Use a Loop in Java?

The for loop in Java runs a specific block of code for the declared number of times. It is implemented for a fixed number of iterations. We will have a look at the syntax of for loop in Java.

for (init_expression; loop_condition; increment/decrement) {
  // code for execution
}

In the syntax above:

  • The “init_expression” executes once before the execution of the code block. 
  • The “loop_condition” depicts the condition. 
  • The “increment/decrement” modifies the value of the “init_expression” to control the loop’s behavior.

Advantages of for Loop

Java for loop offers multiple advantages. Some of them are listed below:

  • The main advantage of “for” Loop is that it is easy to implement.
  • It creates neat and clean code that is easy to read and maintain.
  • It saves space and time while coding since there is no need to repeat the same code again.

Let us see through different examples the implementation of for loop in Java

Example 1: for Loop to Print Integer Values

The code below implements for loop to print the integer values:

class forloop {
    //Declare the Main class of Java
    public static void main(String[] args)
    {
        System.out.println("The numbers printed using for loop are: ");
        //for loop to print the numbers from 0 to 8
        for (int x = 0; x <= 5; x++) {
            //Print the numbers from 0 to 15
            System.out.println(x);
        }
    }
}

In the above code:

  • A class forloop is declared to implement the for loop in Java.
  • The for loop consists of an integer “x” which is initialized with a value “0” and goes up to “5”.
  • The println() method prints the integer value from 0 to 5.

Output

The output shows that the integer values from 0 to 5 are printed on the screen using the for loop. 

Example 2: Code Implementation of Nested for Loop in Java

The term nested for loop is described as a for loop declared in another for loop. The below code explains the implementation of nested for loop in Java:

//Declare a class
public class Nestedfor{      //The main class of Java
public static void main(String[] args) { 
System.out.println("NESTED for LOOP");
//The first for loop as x
for(int x=1;x<=3;x++){ 
//The nested for loop as y
for(int y=1;y<=3;y++){ 
        System.out.println("Hello"+" "+y); 
}
} 
} 
}

In the above Java code:

  • First, a class named Nestedfor is declared.
  • Within the main class, the println() method prints a statement accordingly..
  • After that, the first for loop is used that iterates over the integer values from 1 to 3.
  • The second for loop is nested for loop since it is declared within the first for loop.
  • The output is printed using the println() method.

Output

The output below depicts the implementation of a nested for loop in Java.

Example 3: Program to Print the Sum of Natural Numbers

The below code uses a for loop to get the sum of natural numbers up to the specified value.

class naturalno{
  public static void main(String[] args) {
      System.out.println("PROGRAM TO PRINT NATURAL NUMBERS");
      //Initialize the Sum and the number
    int sums = 0;
    int numb = 560;
    //for Loop to declare the integer values and print the sum
    for (int x = 1; x <= numb; x++) {
      sums= sums+x ;  
    }
    System.out.println("The Sum of the number is  = " + sums);
  }
}

In the code above:

  • A class for natural numbers is declared.
  • Two variables named “sums” and “numb” are declared and initialized with the integer values 0 and 560, respectively.
  • The for loop is iterated from x= 1 to 560 and each iteration works in a manner that the value of the sum is increased by 1.
  • The output is printed using the println() method.

Output

The output below prints the sum of natural numbers up to the specified value using the for loop.

This sums up the implementation of for loop in Java.

Conclusion

The for loop in Java is responsible for running a specific code block for a declared number of times. It is implemented for a fixed number of iterations. It creates a clean code that is easily readable, maintainable, and reusable. In this article, we have implemented code examples to show how the for loop works in Java.