[FIXED] How to make a Java Main Menu Loop after using a case

Issue

I am pretty dang new to Java, but being familiar with some other programming languages, I know the basic lay out of a lot of it. One thing I am struggling with is looping menus, specifically a main menu.

I have tirelessly researched methods of it, but none seem to apply or work to my program. I'm assuming its something silly and small that I'm missing in my more-so basic program.

Check it below, thanks for any tips.

    import java.util.Scanner;
public class basicCalc {

    public static void main(String[] args) {
        // TODO Auto-generated method stub

        Scanner input = new Scanner(System.in);
        boolean mainLoop = true;

        int choice;
        do{
            System.out.println("Calculator Main Menu\n");
            System.out.print("1.) Addition \n");
            System.out.print("2.) Subtraction.\n");
            System.out.print("3.) Multiplication.\n");
            System.out.print("4.) Division.\n");
            System.out.print("5.) Generate Random Number.\n");
            System.out.print("6.) Exit\n");
            System.out.print("\nEnter Your Menu Choice: ");

            choice = input.nextInt();


        }

        while(choice >7);

        switch(choice){

        case 1:
            //Definitions
            int adNumf, adNuml, sum;
            System.out.print("Please Enter The First Number: ");
            adNumf = input.nextInt();
            System.out.print("\nPlease Enter The Second Number: ");
            adNuml = input.nextInt();
            sum = adNumf + adNuml;
            System.out.print("The Sum Of Those Numbers is: " +sum);
            break;

        case 2: 
            int subNum1, subNum2, sum2;
            System.out.println("\nPlease Enter The First Number: ");
            subNum1 = input.nextInt();
            System.out.println("Please Enter The Second Number: ");
            subNum2 = input.nextInt();
            sum2 = subNum1 - subNum2;
            System.out.println("The Subtraction Leaves The Number: " +sum2);
            break;

        case 3:
            int multNum1, multNum2, multTotal;

            // Gather Input
            System.out.println("Please Enter The First Number To Multiply: ");
            multNum1 = input.nextInt();
            System.out.println("Please Enter The Second Number To Multiply: ");
            multNum2 = input.nextInt();

            // This will Multiply the Numbers
            multTotal = multNum1 * multNum2;

            //Display Final
            System.out.println("The Multiplied Numbers Are: " +multTotal);
            break;

        case 4: 
            //Definitions
            double divNum1, divNum2, divTotal;
            System.out.println("Enter Your Numerator ");
            divNum1 = input.nextInt();
            System.out.println("Enter Your Denominator ");
            divNum2 = input.nextInt();
            if(divNum2 == 0){
                System.out.println("Zero is Not divisable, please select a new denominator: ");
                divNum2 = input.nextInt();
            }
            divTotal = divNum1 / divNum2;
            System.out.println("Your divisor is: " +divTotal);
            break;

        case 5:
            double limL, limH, rand;
            System.out.println("Enter Your Low Limit: ");
            limL = input.nextInt();
            System.out.println("Enter Your High Limit ");
            limH = input.nextInt();

            //Equation to keep numbers within bounds
            rand = limL + (Math.random() * ((limH - limL) + 1));
            System.out.println("Given Your Limits, the Random Number will be: " +rand);
            break;

        case 6: 
            System.out.println("Exiting Program...");
            System.exit(0);
             break;
        }



        // Bad Menu Option Direct
    if (choice > 6 || choice < 1){
        System.out.println("This is not a valid Menu Option! Please Select Another.");
        do{
            choice = input.nextInt();
        }
        while(choice < 7 );
    }
    // End bad menu option  


    }

}

Solution

You can give whole code(from displaying menu) inside a while loop and give condition as true so that after using a case it will automatically repeat(as you are using 6 to EXIT). And if any invalid input is given for eg:10 the case will go to default section and will execute the code there

import java.util.Scanner;
public class basicCalc {

public static void main(String[] args) {
    // TODO Auto-generated method stub

    Scanner input = new Scanner(System.in);
    boolean mainLoop = true;

    int choice;
    while(true){
        System.out.println("Calculator Main Menu\n");
        System.out.print("1.) Addition \n");
        System.out.print("2.) Subtraction.\n");
        System.out.print("3.) Multiplication.\n");
        System.out.print("4.) Division.\n");
        System.out.print("5.) Generate Random Number.\n");
        System.out.print("6.) Exit\n");
        System.out.print("\nEnter Your Menu Choice: ");

        choice = input.nextInt();




    switch(choice){

    case 1:
        //Definitions
        int adNumf, adNuml, sum;
        System.out.print("Please Enter The First Number: ");
        adNumf = input.nextInt();
        System.out.print("\nPlease Enter The Second Number: ");
        adNuml = input.nextInt();
        sum = adNumf + adNuml;
        System.out.print("The Sum Of Those Numbers is: " +sum);
        break;

    case 2: 
        int subNum1, subNum2, sum2;
        System.out.println("\nPlease Enter The First Number: ");
        subNum1 = input.nextInt();
        System.out.println("Please Enter The Second Number: ");
        subNum2 = input.nextInt();
        sum2 = subNum1 - subNum2;
        System.out.println("The Subtraction Leaves The Number: " +sum2);
        break;

    case 3:
        int multNum1, multNum2, multTotal;

        // Gather Input
        System.out.println("Please Enter The First Number To Multiply: ");
        multNum1 = input.nextInt();
        System.out.println("Please Enter The Second Number To Multiply: ");
        multNum2 = input.nextInt();

        // This will Multiply the Numbers
        multTotal = multNum1 * multNum2;

        //Display Final
        System.out.println("The Multiplied Numbers Are: " +multTotal);
        break;

    case 4: 
        //Definitions
        double divNum1, divNum2, divTotal;
        System.out.println("Enter Your Numerator ");
        divNum1 = input.nextInt();
        System.out.println("Enter Your Denominator ");
        divNum2 = input.nextInt();
        if(divNum2 == 0){
            System.out.println("Zero is Not divisable, please select a new denominator: ");
            divNum2 = input.nextInt();
        }
        divTotal = divNum1 / divNum2;
        System.out.println("Your divisor is: " +divTotal);
        break;

    case 5:
        double limL, limH, rand;
        System.out.println("Enter Your Low Limit: ");
        limL = input.nextInt();
        System.out.println("Enter Your High Limit ");
        limH = input.nextInt();

        //Equation to keep numbers within bounds
        rand = limL + (Math.random() * ((limH - limL) + 1));
        System.out.println("Given Your Limits, the Random Number will be: " +rand);
        break;

    case 6: 
        System.out.println("Exiting Program...");
        System.exit(0);
         break;
    default :
             System.out.println("This is not a valid Menu Option! Please Select Another");
             break;

    }


    }




    }

   }

Answered By - Anoop LL

Answer Checked By - Mildred Charles (PHPFixing Admin)