课后作业220106

课后作业

已知数据手机号数组：

String[] phones = {“13804010040”,“13804010041”,“13804010042”,

“13804010043”,“13804010044”,“13804010045”,

“13804010046”,“13804010047”,“13804010044”,

“13804010054”,“13804010055”,“13804010056”,

“13804010058”,“13804010059”,“13804010060”,

“13804010061”,“13804010062”,“13804010063”,

“13804010064”,“13804010065”,“13804010066”,

“13804010067”,“13804010068”,“13804010069”,

“13804010070”,“13804010071”,“13804010072”,

“13804010073”,“13804010074”,“13804010075”,

“13804010045”,“13804010057”,“13804010063”,

“13804010058”,“13804010069”,“13804010066”}

1.使用集合，快速去除重复的手机号，将去重后手机号存

放的List集合中，输出去重后有多少个手机号，13804010099这个手机号是否存在

2.已知上面手机号数组，将数组转为集合，然后使用map集合存储每个手机号出现的次数，并遍历输出

public static void main(String[] args) {
        String[] phones = {"13804010040", "13804010041", "13804010042",
                "13804010043", "13804010044", "13804010045",
                "13804010046", "13804010047", "13804010044",
                "13804010054", "13804010055", "13804010056",
                "13804010058", "13804010059", "13804010060",
                "13804010061", "13804010062", "13804010063",
                "13804010064", "13804010065", "13804010066",
                "13804010067", "13804010068", "13804010069",
                "13804010070", "13804010071", "13804010072",
                "13804010073", "13804010074", "13804010075",
                "13804010045", "13804010057", "13804010063",
                "13804010058", "13804010069", "13804010066"};
        // 去重，转变为list集合
        List<String> listPhones = Arrays.stream(phones).distinct().collect(Collectors.toList());
        // 遍历list集合
        listPhones.forEach(one -> System.out.print(one + " "));
        System.out.println();
        // 手机号是否存在
        if (listPhones.contains("13804010099")) {
            System.out.println("13804010099存在！");
        } else {
            System.out.println("13804010099不存在!");
        }

        // 每个手机号出现的次数
        System.out.println("第二题：");
        Map<String, Integer> hashMap = new HashMap<>();
        for (String phone : phones) {
            if (hashMap.containsKey(phone)) {
                hashMap.put(phone, hashMap.get(phone) + 1);
            } else {
                hashMap.put(phone, 1);
            }
        }
        hashMap.forEach((key, value) -> System.out.println(key + "的次数是：" + value));

    }