Java User Input not ending

Question

I am working on a Java program to find s and t values for a GCD and for some reason my program won't get out of the user input unless I type in the integers 2 and 3 as the input. I don't know why it is doing that, and why it is only accepting those two numbers. If anyone could help me out, I would be very thankful.

Here is my code:

package test;
import java.util.Scanner;
public class test {
public static void main(String [] args) {

    int a;
    int b;
    int div;
    int dive;
    Scanner sc= new Scanner(System.in);
    System.out.println("Enter in values of A and B to find its GCD.");
    a = sc.nextInt();
    b = sc.nextInt();

    int[] Array1 = {1,0,a};
    int[] Array2 = {0,1,b};

    while (Array2[2] !=0) {
        if(Array1[2] > Array2[2])
        {
         div = Array1[2]/Array2[2];
        for (int i = 0; i<Array1.length;i++)
            for (int k = 0; k<Array2.length;k++)
                Array1[i] = Array1[i] - div* Array2[k];


        }
        else
        {
            dive = Array2[2]/Array1[2];
            for (int j = 0; j<Array1.length;j++)
                for (int l = 0; l<Array2.length;l++)
                    Array2[l] = Array2[l]- dive*Array1[j];
        }
      }
    if(Array2[2] == 0)
        System.out.println("S = " + Array1[0] + " t = " + Array1[1]);
    if(Array1[2] == 0)
        System.out.println("S = " + Array2[0] + " t = " + Array2[1]);


}
}

Y.Kakdas · Accepted Answer · 2019-02-28 06:21:41Z

1

The problem is not in your scanner,the problem is your while loop and for loops. Let a=2,b=4 : ( b is Array2[2])

else
    {
        dive = Array2[2]/Array1[2];
        for (int j = 0; j<Array1.length;j++)
            for (int l = 0; l<Array2.length;l++)
                Array2[l] = Array2[l]- dive*Array1[j];
    }

dive=2

j=0 , l=2 --> b = b - 2*1 --> b=2

j=1 , l=2 --> b = b - 2*0 --> b=2

j=2 , l=2 --> b = b - 2*2 --> b=-2

As you can see, your value is not coming to zero,so this makes to loop forever.

answered Feb 28, 2019 at 6:21

Y.Kakdas

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Comments

CodeChanger · Accepted Answer · 2019-02-28 06:32:47Z

0

Your code is running into infinite loop that is because your while condition Array2[2] != 0 is never met.

You can see that by printing Array2[2]'s value to the end of your for loops.

You have to make a different approach.

Hint: Use Euclidean algorithm to calculate GCD.

edited Feb 28, 2019 at 6:32

CodeChanger

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answered Feb 28, 2019 at 6:30

Ravi Singh Lodhi

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