Java练习：数据结构基础练习

柔情只为你懂 2022-11-05 12:50 201阅读 0赞

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。  
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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;
                }
            }
        }
    }

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