[만들어 가면서 배우는 JAVA 플레이그라운드] 구구단

• 이클립스 라인 복사: ctrl + alt + up(down), 라인 이동: alt + up(down)
• 단순 반복

public class Gugudan {
	public static void main(String[] args) {
		// 2단
		System.out.println(2 * 1);
		System.out.println(2 * 2);
		System.out.println(2 * 3);
		System.out.println(2 * 4);
		System.out.println(2 * 5);
		System.out.println(2 * 6);
		System.out.println(2 * 7);
		System.out.println(2 * 8);
		System.out.println(2 * 9);
		// 3단
		System.out.println(3 * 1);
		System.out.println(3 * 2);
		System.out.println(3 * 3);
		System.out.println(3 * 4);
		System.out.println(3 * 5);
		System.out.println(3 * 6);
		System.out.println(3 * 7);
		System.out.println(3 * 8);
		System.out.println(3 * 9);
	}
}

 

• 변수 활용

import java.util.Scanner;

public class Gugudan {
	public static void main(String[] args) {
        // 4단
        int result = 4 * 1;
        System.out.println(result);
        result = 4 * 2;
        System.out.println(result);
        result = 4 * 3;
        System.out.println(result);
        result = 4 * 4;
        System.out.println(result);
        result = 4 * 5;
        System.out.println(result);
        result = 4 * 6;
        System.out.println(result);
        result = 4 * 7;
        System.out.println(result);
        result = 4 * 8;
        System.out.println(result);
        result = 4 * 9;
        System.out.println(result);


        System.out.println("구구단 중 출력할 단은? : ");
        Scanner scanner = new Scanner(System.in);
        int number = scanner.nextInt();
        System.out.println(number * 1);
        System.out.println(number * 2);
        System.out.println(number * 3);
        System.out.println(number * 4);
        System.out.println(number * 5);
        System.out.println(number * 6);
        System.out.println(number * 7);
        System.out.println(number * 8);
        System.out.println(number * 9);
	}
}

• 스캐너를 활용해 사용자에게 입력을 받아 구구단 출력

 

• 반복문 활용

public class Gugudan {
	public static void main(String[] args) {
		// 6단
		int i = 1;
		while (i < 10) {
			System.out.println(6 * i);
			i++;
		}
		
		// 7단
		for (int j = 1; j < 10; j++) {
			System.out.println(7 * j);
		}
	}
}

 

• 조건문 활용

import java.util.Scanner;

public class Gugudan {
	public static void main(String[] args) {
        System.out.println("구구단 중 출력할 단은? : ");
        Scanner scanner = new Scanner(System.in);
        int number = scanner.nextInt();
        
        if (number < 2) {
        	System.out.println("입력값 오류");
        } else if (number > 9) {
        	System.out.println("입력값 오류");
        } else {
            for (int i = 1; i < 10; i++) {
            	System.out.println(i * number);
            }
        }
        
	}
}

 

출처: 

https://www.inflearn.com/course/java-codesquad/unit/7199?tab=curriculum 

https://www.inflearn.com/course/java-codesquad/unit/7200?tab=curriculum 

https://www.inflearn.com/course/java-codesquad/unit/7201?tab=curriculum 

https://www.inflearn.com/course/java-codesquad/unit/7202?tab=curriculum