作业操作2-CFANZ编程社区

1、产生10个1-100的随机数，并放到一个数组中，把数组中大于等于10的数字放到一个list集合中，并打印到控制台。

        public static void main(String[] args) {
        int[] arrs = new int[10];
        List list = new ArrayList();
        for (int i = 0; i < arrs.length; i++) {
            arrs[i] =(int) (Math.random() * 100 + 1);
            System.out.print(arrs[i] + " ");
            if (arrs[i] >= 10){
                list.add(arrs[i]);
            }
        }
        System.out.println(list);
    }

2、已知数组存放一批QQ号码，QQ号码最长为11位，最短为5位 String[] strs ={"12345","67891","12347809933","98765432102","67891","12347809933"}。将该数组里面的所有qq号都存放在LinkedList中，将list中重复元素删除，将list中所有元素分别用迭代器和增强for循环打印出来。

String[] strs ={"12345","67891","12347809933","98765432102","67891","12347809933"};
        //List   有序可以重复      Set 无序不可以重复
        Set<String> set = new HashSet<>();
        for (int i = 0; i < strs.length; i++) {
            set.add(strs[i]);
        }
        System.out.println(set);

        List<String> list = new LinkedList<>();
        Iterator<String> it = set.iterator();
        while (it.hasNext()){
            list.add(it.next());
        }
        System.out.println(list);

        for (String str : list){
            System.out.println(str);
        }

3、用Comparable接口对下列四位同学的成绩做降序排序，如果成绩一样，那在成绩排序的基础上按照年龄由小到大排序。提示：编写一个Student类用来实现Comparable<Student>接口,并在其中重写CompareTo(Student o)方法　　

Student stu1 = new Student("liusan", 20, 90F);
        Student stu2 = new Student("lisi", 22, 90F);
        Student stu3 = new Student("wangwu", 20, 99F);
        Student stu4 = new Student("sunliu", 22, 100F);
        List<Student> list = new ArrayList<>();
        list.add(stu1);
        list.add(stu2);
        list.add(stu3);
        list.add(stu4);
        System.out.println(list);

        //
        Collections.sort(list);
        System.out.println(list);

}
}

class Student implements Comparable<Student>{
    private String name;
    private int age;
    private float score;

    public Student(String name, int age, float score) {
        this.name = name;
        this.age = age;
        this.score = score;
    }

    @Override
    public int compareTo(Student o) {
        if (this.score == o.score){//成绩一样
            return this.age - o.age;//按年龄从小到大排
        }
        return o.score - this.score> 0 ? 1 : -1;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", score=" + score +
                '}';
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public float getScore() {
        return score;
    }

    public void setScore(float score) {
        this.score = score;
    }

Map<Integer,String> map = new HashMap<Integer,String>();
        map.put(1,"张三丰");
        map.put(2,"周芷若");
        map.put(3,"汪峰");
        map.put(4,"灭绝师太");
        System.out.println(map);
        Set<Integer> keys = map.keySet();
        Iterator<Integer> itKey = keys.iterator();
        while(itKey.hasNext()){
            Integer key = itKey.next();
            String value = map.get(key);
            System.out.println(key + ":" +value);
        }
        map.put(5,"李晓红");
        map.remove(1);
        System.out.println(map);
        map.put(2,"周林");
        System.out.println(map);

5、已知有十六支男子足球队参加2020 奥运会。写一个程序，把这16 支球队随机分为4 个组。采用List集合和随机数 2020 奥运会男足参赛国家：科特迪瓦，阿根廷，澳大利亚，塞尔维亚，荷兰，尼日利亚、日本，美国，中国，新西兰，巴西，比利时，韩国，喀麦隆，洪都拉斯，意大利

List<String> list = new ArrayList<>();
        list.add("科特迪瓦");
        list.add("阿根廷");
        list.add("澳大利亚");
        list.add("塞尔维亚");
        list.add("荷兰");
        list.add("尼日利亚");
        list.add("日本");
        list.add("美国");
        list.add("中国");
        list.add("新西兰");
        list.add("巴西");
        list.add("比利时");
        list.add("韩国");
        list.add("喀麦隆");
        list.add("洪都拉斯");
        list.add("意大利");
        Random random = new Random();
        String str;
        for (int i = 0; i < 4; i++) {
            System.out.println((i+1) + "组");
            for (int j = 0; j < 4; j++) {
                str = list.get(random.nextInt(list.size()));
                System.out.print(" " + str);
                list.remove(str);
            }
            System.out.println("\n");
        }
    }