정올 1291 : 구구단 문제

package java_01;
import java.util.Scanner;

public class GuGuDan {
	
	public static int[] dan = new int[2];
	public static boolean checkNumber = false;

	public static void main(String[] args) {
		
		try (Scanner input = new Scanner(System.in)) {
			while (true) {
				
				for (int i = 0; i < dan.length; i++) {
					dan[i] = input.nextInt();
				}
				
				if (checkFunc(dan)) {
					break;
				}
				
				System.out.println("INPUT ERROR!");
			}
		}
		
		printGuGuDan(dan);
		
	} // end of main function 
	
	public static boolean checkFunc(int dan[]) {
		boolean flag = false;
		for (int i = 0; i < dan.length; i++) {
			if (2 <= dan[i] && dan[i] <= 9) {
				flag = true;
			} else {
				flag = false;
			}
		}
		return flag;
	} // end of checkFunc function
	
	public static void printGuGuDan(int dan[]) {
		for (int i = 1; i <= 9; i++) {
			for (int j = 0; j < dan.length; j++) {
				System.out.printf("%d * %d = %d", dan[j], i, dan[j]*i);
				if ( j != dan.length-1) {
					System.out.print("\t");
				} else {
					System.out.println();
				}
			}
		}
	} // end of printGuGuDan function 
}