新・明解Java入門　演習7-10

En07_10.java

import java.util.Random;
import java.util.Scanner;

public class En07_10 {

	static Scanner stdIn = new Scanner(System.in);

	public static void main(String[] args) {
		Random rand = new Random();

		System.out.println("暗算力トレーニング！！");

		do {
			int randomTest = rand.nextInt(4);

			int x = rand.nextInt(900) + 100; // 3桁の数
			int y = rand.nextInt(900) + 100; // 3桁の数
			int z = rand.nextInt(900) + 100; // 3桁の数

			Roop: while (true) {
				switch (randomTest) {
				case 0:
					System.out.print(x + " + " + y + " + " + z + " = ");
					break;
				case 1:
					System.out.print(x + " + " + y + " - " + z + " = ");
					break;
				case 2:
					System.out.print(x + " - " + y + " + " + z + " = ");
					break;
				case 3:
					System.out.print(x + " - " + y + " - " + z + " = ");
					break;
				}
				int k = stdIn.nextInt(); // 読み込んだ値

				switch (randomTest) {
				case 0:
					if (k == x + y + z) {
						break Roop;
					} else {
						break;
					}
				case 1:
					if (k == x + y - z) {
						break Roop;
					} else {
						break;
					}
				case 2:
					if (k == x - y + z) {
						break Roop;
					} else {
						break;
					}
				case 3:
					if (k == x - y - z) {
						break Roop;
					} else {
						break;
					}
				}
				System.out.println("違いますよ！");
			}
		} while (confirmRetry());

	}

	// 続行の確認
	static boolean confirmRetry() {
		int cont;
		do {
			System.out.print("もう一度？<Yes…1/No…0>：");
			cont = stdIn.nextInt();
		} while (cont != 0 && cont != 1);
		return cont == 1;
	}

}