DebugJava.java

import java.util.Scanner;

/*
 *
 * This program does not work as intended.  It contains both
 * compile-time errors (errors that prevent the compiler from even
 * running the program) and run-time errors (errors where the
 * program does not function as intended).  Your job is to fix
 * this program so that it works correctly.  Note that it is *not*
 * sufficient to simply fix the compiler errors; you will need to
 * update the logic as well.
 *
 * This program attempts to read a positive integer from the user,
 * then check whether that integer is prime (whether its only
 * divisors are 1 and itself).  If so, it prints a message saying
 * that the number is prime; otherwise it says that the number is
 * composite.
 */

public class DebugJava {
    /* Reads a number from the user and reports whether or not it
     * is prime.
     */
    public void run() {
        /* Get the value from the user. */
        int value = readPositiveInt();

        /* Check whether or not it is prime. */
        if (isPrime(value)) {
            System.out.println(value + " is prime.")
        } else {
            System.out.println(value + " is composite.");
        }
    }

    /**
     * Given a positive integer, returns whether that integer is
     * prime.
     *
     * @param value The value to test.
     * @return Whether or not it is prime.
     */
    private boolean isPrime(int value) {
        /* Try all possible divisors of the number.  If any of them
         * cleanly divide the number, we return that the number is
         * composite.
         */
        for (int divisor = 0; divisor <= value; divisor++) {
            if (value % divisor == 0) {
                return false;
            }
        }
    }

    /**
     * Reads a positive integer from the user and returns it.
     *
     * @return A positive integer entered by the user.
     */
    private int readPositiveInt() {

        Scanner input = new Scanner(System.in);

        /* Get an initial value. */
        System.out.println("Enter a positive integer: ");
        int value = input.nextInt();

        /* If the value was nonpositive, reprompt the user. */
        while (value <= 0) {
            System.out.println("Enter a positive integer: ");
            int value = input.nextInt();
        }

        return value;
    }
}