1、模拟斗地主public class PlayCards {
public static void main(String[] args) {
String[] color = {"黑桃", "梅花", "方片", "红桃"};
String[] num = {"A", "2", "3", "4", "5", "6", "7", "8", "9", "10", "J", "Q", "K"};
ArrayList<String> cards = new ArrayList<>();
//洗牌
for (int i = 0; i < color.length; i ) {
for (int j = 0; j < num.length; j ) {
cards.add(color[i] num[j]);
}
}
cards.add("大王");
cards.add("小王");
Collections.shuffle(cards);
ArrayList<String> 林志玲 = new ArrayList<>();
ArrayList<String> 林心如 = new ArrayList<>();
ArrayList<String> 舒淇 = new ArrayList<>();
//留下3张底牌
for (int i = 0; i < cards.size() - 3; i ) {
if (i % 3 == 0) {
林志玲.add(cards.get(i));
} else if (i % 3 == 1) {
林心如.add(cards.get(i));
} else if (i % 3 == 2) {
舒淇.add(cards.get(i));
}
}
System.out.println("林志玲：" 林志玲);
System.out.println("林心如：" 林心如);
System.out.println("舒淇：" 舒淇);
System.out.println("底牌：");
for (int i = cards.size() - 3; i < cards.size(); i ) {
System.out.println(cards.get(i));
}
}
}
2、学生管理系统 IO 版本先在项目的根目录下创建 student.txt,用户存储用户输入的信息。
学生类:
public class Student {
private String id;
private String name;
private String age;
private String address;
// 空参和有参构造方法
// getter、setter方法
}
系统程序:
public class StudentManagerIO {
public static void main(String[] args) throws IOException {
String fileName = "student.txt";
//为了使主程序回到这里，使用循环
while (true) {
//学生管理系统主界面
System.out.println("----------欢迎来到学生管理系统----------");
System.out.println("1 查看所有学生");
System.out.println("2 添加学生");
System.out.println("3 删除学生");
System.out.println("4 修改学生");
System.out.println("5 退出系统");
System.out.println("请输入你的选择：");
//创建键盘录入对象
Scanner scanner = new Scanner(System.in);
String choiceString = scanner.nextLine();
//使用 Switch语句
switch (choiceString) {
case "1":
//查看所有学生
findAllStudent(fileName);
break;
case "2":
//添加学生
addStudent(fileName);
break;
case "3":
//删除学生
deleteStudent(fileName);
break;
case "4":
//修改学生
updateStudent(fileName);
break;
case "5":
//退出
System.out.println("谢谢你的使用");
System.exit(0); //JVM退出
default:
System.out.println("你的输入有误，请重新选择");
}
}
}
//从文件中读取数据到集合
private static void readData(String fileName, ArrayList<Student> array) throws IOException {
BufferedReader reader = new BufferedReader(new FileReader(fileName));
String line;
while ((line = reader.readLine()) != null) {
String[] datas = line.split(",");
Student student = new Student();
student.setId(datas[0]);
student.setName(datas[1]);
student.setAddress(datas[2]);
student.setAddress(datas[3]);
array.add(student);
}
reader.close();
}
//把集合中的数据写入文件
private static void writeData(String fileName, ArrayList<Student> array) throws IOException {
BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
for (int i = 0; i < array.size(); i ) {
Student student = array.get(i);
StringBuffer sb = new StringBuffer();
sb.append(student.getId()).append(",").append(student.getName()).append(",")
.append(student.getAge()).append(",").append(student.getAddress());
writer.write(sb.toString());
writer.newLine();
writer.flush();
}
writer.close();
}
//修改学生
public static void updateStudent(String fileName) throws IOException {
ArrayList<Student> array = new ArrayList<>();
readData(fileName, array);
Scanner sc = new Scanner(System.in);
System.out.println("请输入你要修改的学生的学号：");
String id = sc.nextLine();
int index = -1;
for (int i = 0; i < array.size(); i ) {
Student student = array.get(i);
if (student.getId().equals(id)) {
index = i;
break;
}
}
if (index == -1) {
System.out.println("不好意思,你要修改的学号对应的学生信息不存在,请回去重新你的选择");
} else {
System.out.println("请输入学生新姓名：");
String name = sc.nextLine();
System.out.println("请输入学生新年龄：");
String age = sc.nextLine();
System.out.println("请输入学生新居住地：");
String address = sc.nextLine();
Student student = new Student();
student.setId(id);
student.setName(name);
student.setAge(age);
student.setAddress(address);
array.set(index, student);
writeData(fileName, array);
System.out.println("修改成功！！！");
}
}
//删除学生
public static void deleteStudent(String fileName) throws IOException {
ArrayList<Student> array = new ArrayList<>();
readData(fileName, array);
Scanner scanner = new Scanner(System.in);
System.out.println("请输入需要删除的学生学号：");
String id = scanner.nextLine();
int index = -1;
for (int i = 0; i < array.size(); i ) {
Student student = array.get(i);
if (student.getId().equals(id)) {
index = i;
break;
}
}
if (index == -1) {
System.out.println("不好意思，你要删除的学生信息不存在，请重新选择");
} else {
array.remove(index);
writeData(fileName, array);
System.out.println("删除成功！！");
}
}
//添加学生信息
public static void addStudent(String fileName) throws IOException {
ArrayList<Student> array = new ArrayList<>();
//从文件中读取数据到集合
readData(fileName, array);
Scanner scanner = new Scanner(System.in);
String id;
while (true) {
System.out.println("请输入学生学号：");
id = scanner.nextLine();
//判断学号是否被占用
boolean flag = isExist(array, id);
if (flag) {
System.out.println("对不起，你输入的学号被占用，请重新输入");
} else {
break;
}
}
System.out.println("请输入学生姓名：");
String name = scanner.nextLine();
System.out.println("请输入学生年龄：");
String age = scanner.nextLine();
System.out.println("请输入学生住址：");
String address = scanner.nextLine();
Student student = new Student();
student.setId(id);
student.setName(name);
student.setAge(age);
student.setAddress(address);
array.add(student);
writeData(fileName, array);
System.out.println("添加成功！！");
}
//判断学号是否被占用
private static boolean isExist(List<Student> array, String id) {
for (int i = 0; i < array.size(); i ) {
Student student = array.get(i);
if (student.getId().equals(id)) {
return true;
}
}
return false;
}
//查看所有学生
public static void findAllStudent(String fileName) throws IOException {
ArrayList<Student> array = new ArrayList<>();
readData(fileName, array);
if (array.size() == 0) {
System.out.println("不好意思，暂时没有学生信息可供查询，请重新选择");
return;
}
System.out.println("学号\t姓名\t年龄\t居住地");
array.forEach(student ->
System.out.println(student.getId() "\t" student.getName() "\t"
student.getAddress() "\t" student.getAddress()
)
);
}
}
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