1、定义一个方法 listTest(ArrayList list, String name)，要求返回 name 在 list 里面第一次出 现的索引，如果 name 没出现过返回-1。

2、已知数组存放一批 QQ 号码,长度 5-11 位， String[] strs = {“10001”,“10086”,“12347806666”,“45612378901”,“10001”,“12347806666”}。 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。

3、请随机生成一注双色球号码。(要求同色号码不重复)。双色球规则:双色球每注投注号码由 6 个红色 球号码和 1 个蓝色球号码组成。红色球号码从 1—33 中选择;蓝色球号码从 1—16 中选择;

4、分别用 Comparable 和 Comparator 两个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。

代码如下：

1.

public class ListTestDemo {
    public static void main(String[] args) {
        ArrayList<String> nameDirectory = new ArrayList<>();
        nameDirectory.add("张三");
        nameDirectory.add("李四");
        nameDirectory.add("王五");
        nameDirectory.add("刘六");

        while(true){
            System.out.println("=======名字检索系统=======");
            Scanner scanner = new Scanner(System.in);
            String input = scanner.nextLine();
            int index = listTest(nameDirectory,input);
            if(index == -1){
                System.out.println(input + "不在该链表中");
            }else{
                System.out.println(input + "的index为" + index);
            }
        }
    }
    public static int listTest(ArrayList<String> list, String name){
        int len = list.size();
        for(int i = 0; i < len; i++){
            if(list.get(i).equals(name)){
                return i;
            }
        }
        return -1;
    }
}

2.

public class RemoveRepeat {
    public static void main(String[] args) {
        String[] strs = {"10001", "10086", "12347806666", "45612378901", "10001", "12347806666"};
        LinkedList<String> list = getList(strs);
        //增强型for循环
        System.out.println("------增强型for循环------");
        for(String i : list){
            System.out.println(i);
        }
        //迭代器
        System.out.println("---------迭代器---------");
        Iterator<String> iterator = list.iterator();
        while(iterator.hasNext()){
            String s = iterator.next();
            System.out.println(s);
        }
    }

    public static LinkedList<String> getList(String[] strs){
        LinkedList<String> list = new LinkedList<String>();
        for(int i=0; i<strs.length; i++){
            if(list.contains(strs[i])){
                continue;
            }
            list.add(strs[i]);
        }
        return list;
    }
}

3

public class BallNumber {
    public static void main(String[] args) {
        while(true){
            menu();
        }

    }

    public static int menu(){
        System.out.println("======欢迎来到双色球游戏======");
        System.out.println("请输入相应编号继续游戏：");
        System.out.println("1-开始游戏  2-退出游戏");
        Scanner scanner = new Scanner(System.in);
        String input = scanner.nextLine();
        int num = -1;
        try{
            num = Integer.parseInt(input);
        }catch(NumberFormatException e){
            System.out.println("请输入数字");
            return menu();
        }
        if(num < 1 || num > 2){
            System.out.println("请输入正确的数字");
            return menu();
        }

        if(num == 1){
            getball();
        }else{
            System.exit(1);
        }
        return -1;
    }
    public static void getball(){
        System.out.println("正在生成一注双色球号码...");
        System.out.println("生成成功！");
        System.out.println("红色球号码为：");
        LinkedList<Integer> redBall = getRedBall();
        for(Integer i : redBall){
            System.out.print(i);
            System.out.print('\t');
        }
        System.out.println();//换行
        System.out.println("蓝色球号码为：");
        int blueNum = getBlueBall();
        System.out.println(blueNum);
    }
    public static LinkedList<Integer> getRedBall(){
        LinkedList<Integer> red = new LinkedList<>();
        Random random = new Random();
        while(red.size() < 6){
            int code = (int)(1 + Math.random() * 33);
            if(red.contains(code)){
                continue;
            }
            red.add(code);
        }
        return red;
    }

    public static int getBlueBall(){
        Random random = new Random();
        return (int)(1 + Math.random() * 16);
    }

}

4

public class compareTest {

    public static void main(String[] args) {
        Student s1 = new Student("贾宝玉",14,88.5);
        Student s2 = new Student("林黛玉",13,90.5);
        Student s3 = new Student("史湘云",13,85.5);
        Student s4 = new Student("薛宝钗",15,91.0);
        Student s5 = new Student("工具人",15,88.5);
        ArrayList<Student> studentList = new ArrayList<>();
        studentList.add(s1);
        studentList.add(s2);
        studentList.add(s3);
        studentList.add(s4);
        studentList.add(s5);
        System.out.println("--------comparable实现方法--------");
        System.out.println("原来的顺序");
        for(Student s : studentList){
            System.out.println(s);
        }
        System.out.println("--------------"+'\n' + "现在的顺序：");
        Collections.sort(studentList);
        for(Student s : studentList){
            System.out.println(s);
        }

        System.out.println("--------comparator实现方法--------");
        System.out.println("原来的顺序");
        for(Student s : studentList){
            System.out.println(s);
        }
        System.out.println("--------------"+'\n' + "现在的顺序：");
        Collections.sort(studentList,new comparator());
        for(Student s : studentList){
            System.out.println(s);
        }
    }

    static class Student implements Comparable<Student>{
        private String name;
        private int age;
        private double points;

        public Student(String name, int age, double points) {
            this.name = name;
            this.age = age;
            this.points = points;
        }

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

        @Override
        public int compareTo(Student o) {
            if(o.points == this.points){
                return this.age - o.age;
            }
            if(o.points - this.points > 0){
                return 1;
            }else if(o.points - this.points < 0){
                return -1;
            }else{
              return 0;
            }

        }
    }

    static class comparator implements Comparator<Student> {

        @Override
        public int compare(Student o1, Student o2) {
            if(o1.points == o2.points){
                return o1.age - o2.age;
            }

            if(o1.points - o2.points > 0){
                return -1;
            }else if(o1.points - o2.points < 0){
                return 1;
            }else{
                return 0;
            }
        }
    }
}