302班

import javax.swing.JOptionPane;
public class GreatestCommonDivistor

{
 public static void main(String[] args)
 {

  //輸入第一個數
  String strA=JOptionPane.showInputDialog(null,"Enter the first number:","Input First",JOptionPane.QUESTION_MESSAGE);
     int numA=Integer.parseInt(strA);

//輸入第二個數
  String strB=JOptionPane.showInputDialog(null,"Enter the second number:","Input Second",JOptionPane.QUESTION_MESSAGE);
  int numB=Integer.parseInt(strB);
  

//建立一個歷時值存儲公約數
  int gcd=1;
  for(int k=1;k<=numA&&k<=numB;k++)
  if(numA%k==0&&numB%k==0)
   gcd=k;

//輸出結果
  System.out.println("The greatest common of the two numbers is  "+gcd );
 }
}

運行結果如圖：