Restart a Program in Java

  1. Use a do-while Conditional Statement
  2. Use a do-while Conditional Statement Without a Stopping Condition
  3. Use Recursion to Restart a Program
  4. Use Recursion to Restart a Program Without a Stopping Condition
Restart a Program in Java

In a menu-driven program or a game, we require an option to restart or reset our program. We can restart a program in Java by recursively calling a function or using conditional loop statements.

Use a do-while Conditional Statement

import java.util.*;
import java.util.Scanner;


class Main
{

  public static int addNumbers(int a, int b)
  {
    return a + b;
  }

  public static void main(String[] args)
  {
    boolean flag=false;

    Scanner sc= new Scanner(System.in);
    do
    {
    System.out.print("Enter the first number: ");
    int num1= sc.nextInt();
    System.out.print("Enter the second number: ");
    int num2= sc.nextInt();
    int result = addNumbers(num1, num2);
    System.out.println("The sum is: " + result);
    System.out.print("Do you want to add more numbers? Enter y for yes and n for no. ");
    char input = sc.next().charAt(0);
    if(input == 'y')
    {
        flag=true;
    }
    else
    {
        flag=false;
    }
    }while(flag);

  }
}

Output:

Enter the first number: 8
Enter the second number: 7
The sum is: 15
Do you want to add more numbers? Enter y for yes and n for no. y
Enter the first number: 9
Enter the second number: 4
The sum is: 13
Do you want to add more numbers? Enter y for yes and n for no. n

The above code displays the functionality of a conditional loop for restarting a function again; as long as the user inputs y, the program will restart.

Use a do-while Conditional Statement Without a Stopping Condition

import java.util.*;
import java.util.Scanner;


class Main
{

  public static int addNumbers(int a, int b)
  {
    return a + b;
  }

  public static void main(String[] args)
  {
    boolean flag=true;

    Scanner sc= new Scanner(System.in);
    do
    {
    System.out.print("Enter the first number: ");
    int num1= sc.nextInt();
    System.out.print("Enter the second number: ");
    int num2= sc.nextInt();
    int result = addNumbers(num1, num2);
    System.out.println("The sum is: " + result);
    }while(flag);

  }
}

Output:

Enter the first number: 8
Enter the second number: 7
The sum is: 15
Enter the first number: 9
Enter the second number: 4
The sum is: 13
Enter the first number: .....

The above code displays the functionality of a conditional loop for restarting a function an infinite number of times. The only way to stop the program from restarting is to close the program.

Use Recursion to Restart a Program

import java.util.*;
import java.util.Scanner;


class Main
{

  public static void addNumbers(int a, int b, int c)
  {
    Scanner sc= new Scanner(System.in);
    if (c==0)
    {
        int result= a + b;
        System.out.println("The sum is: " + result);
        return;
    }
    int result= a + b;
    System.out.println("The sum is: " + result);
    System.out.print("Enter the first number: ");
    int num1= sc.nextInt();
    System.out.print("Enter the second number: ");
    int num2= sc.nextInt();
    c--;
    addNumbers(num1,num2,c);
  }

  public static void main(String[] args)
  {
    Scanner sc= new Scanner(System.in);
    System.out.print("Enter the first number: ");
    int num1= sc.nextInt();
    System.out.print("Enter the second number: ");
    int num2= sc.nextInt();
    System.out.print("How many times do you want to restart this program? : ");
    int num3= sc.nextInt();
    addNumbers(num1, num2, num3);

  }
}

Output:

Enter the first number: 5
Enter the second number: 6
How many times do you want to restart this program? : 2
The sum is: 11
Enter the first number: 4
Enter the second number: 5
The sum is: 9
Enter the first number: 7
Enter the second number: 8
The sum is: 15

The above code displays the functionality of a recursive function for restarting itself again. The program will restart as many times as the user requires.

Use Recursion to Restart a Program Without a Stopping Condition

import java.util.*;
import java.util.Scanner;


class Main
{

  public static void addNumbers()
  {
    Scanner sc= new Scanner(System.in);
    System.out.print("Enter the first number: ");
    int num1= sc.nextInt();
    System.out.print("Enter the second number: ");
    int num2= sc.nextInt();
    int result= num1+num2;
    System.out.println("The sum is: " + result);
    addNumbers();
  }

  public static void main(String[] args)
  {
    addNumbers();

  }
}

Output:

Enter the first number: 5
Enter the second number: 3
The sum is: 8
Enter the first number: 8
Enter the second number: 11
The sum is: 19
Enter the first number: ...

The above code displays the functionality of a recursive function for restarting itself again. The program will restart an infinite number of times as there is no stopping condition in the recursive call cycle.

Musfirah Waseem avatar Musfirah Waseem avatar

Musfirah is a student of computer science from the best university in Pakistan. She has a knack for programming and everything related. She is a tech geek who loves to help people as much as possible.

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