How to validate user input in a range? And For Loop issue/confusion

Question

How do I validate the user's input for when you enter a year , the range must be between 1900-2021. I am also confused with using the for loop within my situation. I need to print out the motorcycle accelerating four times and then right after I need the code to print out it braking/deaccelerating 3 times. I have a java class and a Java main class. I tried implementing a separate method to validate year but it ended up crashing the program.

public class Motorcycle {

private int year;
private String make;
private int speed;

/**
 * 
 * @param year
 * @param make 
 */
public Motorcycle(int year, String make) {
    this.year = year;
    this.make = make;
    this.speed = 0;
}
public Motorcycle(){
    this.year = 0;
    this.make = "";
    this.speed = 0;
}

public void setYear(int year) {
    this.year = year;
}

public void setMake(String make) {
    this.make = make;
}

public void setSpeed(int speed) {
    this.speed = speed;
}

public int getYear() {
    return year;
}

public String getMake() {
    return make;
}

public int getSpeed() {
    return speed;
}

public void accelerate() {
    this.speed += 5;
}

public void brake() {
    this.speed -= 5;
}

@Override
public String toString() {
    return "A " + year +" " + make + " going "+ speed +" miles per hour";



import java.util.*;

public class MotorcycleDemo {

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

    Scanner keyboard = new Scanner(System.in);

    System.out.println("Enter the year of your Motorcycle");  //validate year 1900 -2021 
    year = keyboard.nextInt();

    System.out.println("Enter the make of your Motorcycle(such as, Harley, Kawasaki)");
    String maker = keyboard.next();

    Motorcycle motor1 = new Motorcycle(year, maker);

    System.out.println(motor1); //account for 0 speed toString()
    for (int i = 0; i <= 3; i++) {            //use for loop  //accelerate 4 times and brake 3 times 
        motor1.accelerate();
        System.out.println(motor1);
        //System.out.println("A " + year + " " + maker + " going " + motor1.getSpeed() + "miles per hour.");
        //to String method     
    }
    for (int i = 0; i <= 3; i++);
    {

        motor1.brake();
        System.out.println(motor1);

    }

}

}

If the motorcycle accelerates 4 times and brakes three times, then the output should display: "A year and make (motorcycle brand) is going speed mph. Starting at speed 0 mph and reaching max speed of 20 and then deaccelerating 4 times concluding the speed to be 5 mph.

Any help is appreciated and thanks in advance. :)

Arrakha · Accepted Answer · 2021-03-21 12:59:02Z

2

Then try setting up a while/do-while loop around your input handling. Keep the loop running if the input is incorrect by setting a boolean value to be the same as the while condition, and break out of the loop if the answer is correct

    public static void main(String[] args) {

        int year;
        int currentYear = Calendar.getInstance().get(Calendar.YEAR); //Creating current year
        boolean looping = false;

        do {
            Scanner keyboard = new Scanner(System.in);
            System.out.println("Enter the year of your Motorcycle");  //validate year 1900 -2021
            year = keyboard.nextInt();

            if (year < 1900 || year > currentYear) {
                looping = true;
                System.out.println("Invalid year!\nPlease type in valid year!");
            } else
                System.out.println("Enter the make of your Motorcycle(such as, Harley, Kawasaki)");
                String maker = keyboard.next();
            //Put condition here too if necessary, and put looping true if input is bad
        } while(looping);  //As long as looping is set true it reruns form

        Motorcycle motor1 = new Motorcycle(year, maker);

        System.out.println(motor1); //account for 0 speed toString()
        for (int i = 0; i <= 3; i++) {            //use for loop  //accelerate 4 times and brake 3 times
            motor1.accelerate();
            System.out.println(motor1);
            //System.out.println("A " + year + " " + maker + " going " + motor1.getSpeed() + "miles per hour.");
            //to String method
        }
        for (int i = 0; i <= 3; i++);
        {

            motor1.brake();
            System.out.println(motor1);

        }
    }

edited Mar 21, 2021 at 12:59

answered Mar 21, 2021 at 11:04

Arrakha

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3 Comments

jaKobT Over a year ago

This does tell the user that they have inputted a invalid year, but the code will still continue to then the ask the "make" rather than ask the user again to input the correct year.

jaKobT Over a year ago

That makes a lot of sense now. Thank you so much!

Arrakha Over a year ago

@jaKobT Please mark the answer as the solution so the question does not stay open or remain unsolved :D –

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