Question

This is my situation:

i need the code to run in a loop, over and over again asking the same question(s) to the user, until the user types a “q” for any point to terminate/exit the loop, thus exiting the program.

The problem is that i tried to used a do-while/while loop, and those loops executes only if the conditions comes out to be true. But i need the condition (“q”) to be false so it can continue the loop. If the condition is true (input.equals(“q”)) , then it just does not nothing because instead of the integer/double, it will use a string (“q”) to calculate the distance.

i have already figured out how to get the distance, the code as is works well, but is there any work-around that i can make the loop continue while the condition is false?

and by the way, i am just barely learning java just in case…

‘.

import java.*;
public class Points {
public static void main(String[] args){

    java.util.Scanner input = new java.util.Scanner(System.in);

    System.out.print("Enter the first X coordinate: ");
    double x1 = input.nextDouble();
    System.out.print("Enter the first Y coordinate: ");
    double y1 = input.nextDouble();
    System.out.print("Enter the second X coordinate: ");
    double x2 = input.nextDouble();
    System.out.print("Enter the second Y coordinate: ");
    double y2 = input.nextDouble();
    System.out.println("(" + x1 + ", " + y1  + ")" + " " + "(" + x2 + ", " + y2+ ")");

    double getSolution = Math.sqrt(((x2-x1) * (x2-x1)) + ((y2-y1) * (y2-y1)));
    System.out.println(getSolution);
    }
}'

Answer 1

The solution to this is to use String line = input.nextLine() instead of nextDouble(). Then you can have a method like:

public static boolean timeToExit(String input) {
    return input.equalsIgnoreCase("q");
}

This method will need to be called each time the user provides input:

if (timeToExit(line)) break;

That will exit a loop.

Now, since you have a String representation of the double, you will need to use Double.parseDouble(line) to turn the String into a number.

Then all you have to do is enclose everything in an infinite loop -> while(true) { }

And, the only time it will exit the loop is if the timeToExit method returned true, and you break the loop.

This all turns into something like:

while (true) {
    ...
    System.out.print("Enter the first X coordinate: ");
    String x1 = input.nextLine();
    if (timeToExit(x1)) break;
    double x1_d = Double.parseDouble(x1);
    ...
}