樂透程式

Lottery.java

package com.vincent.demo;

import java.util.*;
import java.util.stream.Collectors;

public class JavaMain {

    public static void main(String[] args) {
        Set<Integer> selectedNumbers = new HashSet<>();
        Scanner scan = new Scanner(System.in);

        while (selectedNumbers.size() < 6) {
            System.out.printf("請輸入第%d個號碼，已選擇：%s",
                    selectedNumbers.size() + 1, getNumberSummary(selectedNumbers));
            int num = scan.nextInt();
            if (num > 0 && num < 50) {
                selectedNumbers.add(num);
            } else {
                System.out.println("號碼應在1~49之間，請再輸入一次");
            }
        }

        List<Integer> lotteryNumbers = getRandomLotteryNumbers();

        StringBuilder sb = new StringBuilder("樂透開獎號碼：");
        for (int i = 0; i < 6; i++) {
            sb.append(lotteryNumbers.get(i).toString()).append(" ");
        }
        sb.append("\n特別號：").append(lotteryNumbers.get(6));

        System.out.println(sb.toString());
    }

    private static String getNumberSummary(Set<Integer> numbers) {
        List<Integer> nums = numbers.stream()
                .sorted()
                .collect(Collectors.toList());

        StringBuilder sb = new StringBuilder();
        for (Integer num : nums) {
            sb.append(num.toString()).append(" ");
        }

        return sb.toString();
    }
    
    private static List<Integer> getRandomLotteryNumbers() {
        List<Integer> numbers = new ArrayList<>();
        for (int i = 1; i <= 49; i++) {
            numbers.add(i);
        }

        Collections.shuffle(numbers);

        return numbers.stream()
                .limit(7)
                .collect(Collectors.toList());
    }

}

題目來源：
https://www.facebook.com/groups/406460463268219/permalink/539383746642556/