Problem

Create a program that will allow the user to enter in a statement, and output whether the statement is true or false. The statement will be inputted using JOptionPane.showInputDialog. The program will evaluate the truthiness of the statement randomly (just like a real lie detector). The result should be given using System.out.println.

To solve this problem, you will need to understand:

• Input using JOptionPane
• Random number generation
• Relational Operators

Primitive Data Types

Solution

There are three distinct steps in this program:

• reading in input from the user
• calculating the truthiness
• printing out the result.

The first step is to read in the input. You are going to need to use an input dialog box.

 String statement = JOptionPane.showInputDialog(null, "Enter a statement"); 

Don't forget your import statement.

 import javax.swing.*; //needed for JOptionPane 

The next step is to calculate the truthiness of the statement using the random method. The method is part of the Math class, so make sure you import it.

 import java.lang.Math;//needed for Random 

Math.random() will return a decimal value between 0 and 1. By comparing the value to a constant value, we can calculate the truthiness.

 boolean truthiness = Math.random() < 0.5; 

I am using 0.5 so that ~50% of statements will be true. If you are testing the program on someone who is more or less trustworthy, you may want to adjust the value accordingly.

With the truthiness calculated, all that is left is to output the result. This should be done using System.out

 System.out.println("The Statement " + quote + statement + quote + " is " + truthiness); 

You should now have a program that divines truth from statements. For the entire code solution, see below.

Code

Solution Code

/* Class Lie Detector
 * Created by Brendan Curran-Johnson
 * Made in COMP3040
 * A lie detector
 */

import javax.swing.*; //needed for JOptionPane
import java.lang.Math;//needed for Random

public class LieDetector
{
        public static void main (String args[])
        {
                // Get the statement
                String statement = JOptionPane.showInputDialog(null, "Enter a statement");



                //calculate truthiness
                boolean truthiness = Math.random() < 0.5;

                char quote = '"';

                //output solution
                System.out.println("The Statement " + quote + statement + quote + " is " + truthiness);
        }
}