本文目录导读：
我来为您提供几个经典且实用的Java简单设计案例,从易到难逐步进阶。
学生成绩管理系统（基础入门）
import java.util.ArrayList;
import java.util.Scanner;
public class StudentGradeSystem {
private static class Student {
String name;
int id;
double score;
Student(String name, int id, double score) {
this.name = name;
this.id = id;
this.score = score;
}
@Override
public String toString() {
return "学号:" + id + " 姓名:" + name + " 成绩:" + score;
}
}
private ArrayList<Student> students = new ArrayList<>();
private Scanner scanner = new Scanner(System.in);
public void addStudent() {
System.out.print("请输入学号: ");
int id = scanner.nextInt();
System.out.print("请输入姓名: ");
String name = scanner.next();
System.out.print("请输入成绩: ");
double score = scanner.nextDouble();
students.add(new Student(name, id, score));
System.out.println("添加成功！");
}
public void showAll() {
if (students.isEmpty()) {
System.out.println("暂无学生信息");
return;
}
System.out.println("=== 学生成绩列表 ===");
for (Student s : students) {
System.out.println(s);
}
}
public void calculateAverage() {
if (students.isEmpty()) {
System.out.println("暂无学生信息");
return;
}
double sum = 0;
for (Student s : students) {
sum += s.score;
}
System.out.printf("平均成绩: %.2f\n", sum / students.size());
}
public void searchStudent() {
System.out.print("请输入学号查询: ");
int id = scanner.nextInt();
for (Student s : students) {
if (s.id == id) {
System.out.println("找到学生: " + s);
return;
}
}
System.out.println("未找到该学生");
}
public void menu() {
while (true) {
System.out.println("\n=== 学生成绩管理系统 ===");
System.out.println("1. 添加学生");
System.out.println("2. 查看所有学生");
System.out.println("3. 计算平均成绩");
System.out.println("4. 查询学生");
System.out.println("5. 退出");
System.out.print("请选择: ");
int choice = scanner.nextInt();
switch (choice) {
case 1: addStudent(); break;
case 2: showAll(); break;
case 3: calculateAverage(); break;
case 4: searchStudent(); break;
case 5:
System.out.println("再见！");
return;
default: System.out.println("无效选择");
}
}
}
public static void main(String[] args) {
new StudentGradeSystem().menu();
// 使用示例
}
}
简易银行账户系统（面向对象设计）
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;
public class BankSystem {
// 账户类
static class Account {
private String accountNumber;
private String name;
private double balance;
private String openDate;
public Account(String accountNumber, String name, double initialDeposit) {
this.accountNumber = accountNumber;
this.name = name;
this.balance = initialDeposit;
this.openDate = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
}
// 存款
public void deposit(double amount) {
if (amount > 0) {
balance += amount;
System.out.println("存款成功！当前余额: " + balance);
} else {
System.out.println("存款金额必须大于0");
}
}
// 取款
public void withdraw(double amount) {
if (amount > 0 && amount <= balance) {
balance -= amount;
System.out.println("取款成功！当前余额: " + balance);
} else if (amount > balance) {
System.out.println("余额不足，当前余额: " + balance);
} else {
System.out.println("取款金额必须大于0");
}
}
public void showInfo() {
System.out.println("=== 账户信息 ===");
System.out.println("账号: " + accountNumber);
System.out.println("户名: " + name);
System.out.println("余额: " + balance);
System.out.println("开户日期: " + openDate);
}
public String getAccountNumber() {
return accountNumber;
}
}
// 银行系统
static class Bank {
private Account[] accounts = new Account[100];
private int accountCount = 0;
private Scanner scanner = new Scanner(System.in);
public void createAccount() {
if (accountCount >= 100) {
System.out.println("账户已满，无法创建新账户");
return;
}
System.out.print("请输入姓名: ");
String name = scanner.next();
System.out.print("请输入开户金额: ");
double initialDeposit = scanner.nextDouble();
String accountNumber = "2024" + String.format("%03d", accountCount + 1);
accounts[accountCount++] = new Account(accountNumber, name, initialDeposit);
System.out.println("开户成功！账号: " + accountNumber);
}
private Account findAccount(String accountNumber) {
for (int i = 0; i < accountCount; i++) {
if (accounts[i].getAccountNumber().equals(accountNumber)) {
return accounts[i];
}
}
return null;
}
public void deposit() {
System.out.print("请输入账号: ");
String accountNumber = scanner.next();
Account account = findAccount(accountNumber);
if (account == null) {
System.out.println("账号不存在");
return;
}
System.out.print("请输入存款金额: ");
double amount = scanner.nextDouble();
account.deposit(amount);
}
public void withdraw() {
System.out.print("请输入账号: ");
String accountNumber = scanner.next();
Account account = findAccount(accountNumber);
if (account == null) {
System.out.println("账号不存在");
return;
}
System.out.print("请输入取款金额: ");
double amount = scanner.nextDouble();
account.withdraw(amount);
}
public void showAccountInfo() {
System.out.print("请输入账号: ");
String accountNumber = scanner.next();
Account account = findAccount(accountNumber);
if (account == null) {
System.out.println("账号不存在");
} else {
account.showInfo();
}
}
public void menu() {
while (true) {
System.out.println("\n=== 银行账户管理系统 ===");
System.out.println("1. 开户");
System.out.println("2. 存款");
System.out.println("3. 取款");
System.out.println("4. 查询账户信息");
System.out.println("5. 退出");
System.out.print("请选择: ");
int choice = scanner.nextInt();
switch (choice) {
case 1: createAccount(); break;
case 2: deposit(); break;
case 3: withdraw(); break;
case 4: showAccountInfo(); break;
case 5:
System.out.println("感谢使用！");
return;
default: System.out.println("无效选择");
}
}
}
}
public static void main(String[] args) {
Bank bank = new Bank();
bank.menu();
}
}
日历与记事本（文件操作）
import java.io.*;
import java.text.SimpleDateFormat;
import java.util.*;
public class CalendarNote {
private Map<String, List<String>> notes = new HashMap<>();
private static final String FILE_NAME = "notes.txt";
private Scanner scanner = new Scanner(System.in);
public CalendarNote() {
loadNotes();
}
// 添加记事
public void addNote() {
System.out.print("请输入日期(格式: yyyy-MM-dd): ");
String date = scanner.next();
scanner.nextLine(); // 消耗换行符
System.out.print("请输入记事内容: ");
String content = scanner.nextLine();
notes.computeIfAbsent(date, k -> new ArrayList<>()).add(content);
saveNotes();
System.out.println("记事添加成功！");
}
// 查看指定日期的记事
public void showNotes() {
System.out.print("请输入日期(格式: yyyy-MM-dd): ");
String date = scanner.next();
List<String> dayNotes = notes.get(date);
if (dayNotes == null || dayNotes.isEmpty()) {
System.out.println("该日期没有记事");
} else {
System.out.println("=== " + date + " 的记事 ===");
int i = 1;
for (String note : dayNotes) {
System.out.println(i++ + ". " + note);
}
}
}
// 显示本月日历
public void showCalendar() {
Calendar cal = Calendar.getInstance();
int year = cal.get(Calendar.YEAR);
int month = cal.get(Calendar.MONTH);
cal.set(year, month, 1);
int firstDayOfWeek = cal.get(Calendar.DAY_OF_WEEK);
int daysInMonth = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
System.out.println("\n " + year + "年" + (month + 1) + "月");
System.out.println("一 二 三 四 五 六 日");
// 打印空格
for (int i = 1; i < firstDayOfWeek; i++) {
System.out.print(" ");
}
int today = Calendar.getInstance().get(Calendar.DAY_OF_MONTH);
for (int day = 1; day <= daysInMonth; day++) {
String dayStr = String.format("%2d", day);
if (day == today) {
System.out.print("[" + dayStr + "]"); // 标记今天
} else {
System.out.print(" " + dayStr + " ");
}
System.out.print(" ");
if ((day + firstDayOfWeek - 1) % 7 == 0) {
System.out.println();
}
}
System.out.println("\n");
}
// 保存笔记到文件
private void saveNotes() {
try (PrintWriter writer = new PrintWriter(new FileWriter(FILE_NAME))) {
for (Map.Entry<String, List<String>> entry : notes.entrySet()) {
writer.println(entry.getKey());
for (String note : entry.getValue()) {
writer.println(note);
}
writer.println("---END---");
}
} catch (IOException e) {
System.out.println("保存失败: " + e.getMessage());
}
}
// 从文件加载笔记
private void loadNotes() {
File file = new File(FILE_NAME);
if (!file.exists()) return;
try (BufferedReader reader = new BufferedReader(new FileReader(file))) {
String line;
while ((line = reader.readLine()) != null) {
String date = line;
List<String> dayNotes = new ArrayList<>();
while ((line = reader.readLine()) != null && !line.equals("---END---")) {
dayNotes.add(line);
}
notes.put(date, dayNotes);
}
} catch (IOException e) {
System.out.println("加载失败: " + e.getMessage());
}
}
public void menu() {
while (true) {
System.out.println("\n=== 日历与记事本 ===");
System.out.println("1. 查看本月日历");
System.out.println("2. 添加记事");
System.out.println("3. 查看记事");
System.out.println("4. 退出");
System.out.print("请选择: ");
int choice = scanner.nextInt();
switch (choice) {
case 1: showCalendar(); break;
case 2: addNote(); break;
case 3: showNotes(); break;
case 4:
System.out.println("再见！");
return;
default: System.out.println("无效选择");
}
}
}
public static void main(String[] args) {
new CalendarNote().menu();
}
}
简易计算器（GUI版）
import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Calculator extends JFrame implements ActionListener {
private JTextField display;
private double num1 = 0, num2 = 0, result = 0;
private char operator;
private boolean isOperatorClicked = false;
public Calculator() {
setTitle("简易计算器");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new BorderLayout(5, 5));
// 显示区域
display = new JTextField(20);
display.setFont(new Font("Arial", Font.BOLD, 20));
display.setHorizontalAlignment(JTextField.RIGHT);
display.setEditable(false);
add(display, BorderLayout.NORTH);
// 按钮面板
JPanel buttonPanel = new JPanel(new GridLayout(4, 4, 5, 5));
String[] buttons = {
"7", "8", "9", "/",
"4", "5", "6", "*",
"1", "2", "3", "-",
"0", ".", "=", "+"
};
for (String text : buttons) {
JButton button = new JButton(text);
button.setFont(new Font("Arial", Font.BOLD, 18));
button.addActionListener(this);
buttonPanel.add(button);
}
add(buttonPanel, BorderLayout.CENTER);
// 清除按钮
JButton clearButton = new JButton("C");
clearButton.setFont(new Font("Arial", Font.BOLD, 18));
clearButton.addActionListener(e -> {
display.setText("0");
num1 = num2 = result = 0;
isOperatorClicked = false;
});
add(clearButton, BorderLayout.SOUTH);
pack();
setLocationRelativeTo(null);
setVisible(true);
}
@Override
public void actionPerformed(ActionEvent e) {
String command = e.getActionCommand();
if (command.charAt(0) >= '0' && command.charAt(0) <= '9' || command.equals(".")) {
if (isOperatorClicked) {
display.setText(command);
isOperatorClicked = false;
} else {
String text = display.getText();
if (text.equals("0") && !command.equals(".")) {
display.setText(command);
} else {
display.setText(text + command);
}
}
} else if (command.equals("=")) {
num2 = Double.parseDouble(display.getText());
calculate();
display.setText(String.valueOf(result));
isOperatorClicked = true;
} else {
if (!isOperatorClicked) {
num1 = Double.parseDouble(display.getText());
operator = command.charAt(0);
isOperatorClicked = true;
}
}
}
private void calculate() {
switch (operator) {
case '+': result = num1 + num2; break;
case '-': result = num1 - num2; break;
case '*': result = num1 * num2; break;
case '/':
if (num2 != 0) {
result = num1 / num2;
} else {
display.setText("错误: 除数不能为0");
return;
}
break;
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(Calculator::new);
}
}
简易购物车系统（综合应用）
import java.util.*;
public class ShoppingCartSystem {
// 商品类
static class Product {
private String id;
private String name;
private double price;
private int stock;
public Product(String id, String name, double price, int stock) {
this.id = id;
this.name = name;
this.price = price;
this.stock = stock;
}
public String getId() { return id; }
public String getName() { return name; }
public double getPrice() { return price; }
public int getStock() { return stock; }
public void setStock(int stock) { this.stock = stock; }
@Override
public String toString() {
return String.format("编号:%-5s 名称:%-10s 价格:%.2f 库存:%d", id, name, price, stock);
}
}
// 购物车项
static class CartItem {
private Product product;
private int quantity;
public CartItem(Product product, int quantity) {
this.product = product;
this.quantity = quantity;
}
public Product getProduct() { return product; }
public int getQuantity() { return quantity; }
public void setQuantity(int quantity) { this.quantity = quantity; }
public double getSubtotal() {
return product.getPrice() * quantity;
}
}
// 购物车
static class ShoppingCart {
private List<CartItem> items = new ArrayList<>();
public void addItem(Product product, int quantity) {
for (CartItem item : items) {
if (item.getProduct().getId().equals(product.getId())) {
item.setQuantity(item.getQuantity() + quantity);
product.setStock(product.getStock() - quantity);
return;
}
}
items.add(new CartItem(product, quantity));
product.setStock(product.getStock() - quantity);
}
public void removeItem(String productId) {
items.removeIf(item -> item.getProduct().getId().equals(productId));
}
public double getTotalPrice() {
return items.stream().mapToDouble(CartItem::getSubtotal).sum();
}
public void showCart() {
if (items.isEmpty()) {
System.out.println("购物车为空");
return;
}
System.out.println("\n=== 购物车 ===");
int i = 1;
for (CartItem item : items) {
System.out.printf("%d. %s x %d = %.2f\n",
i++, item.getProduct().getName(),
item.getQuantity(), item.getSubtotal());
}
System.out.printf("总计: %.2f\n", getTotalPrice());
}
public List<CartItem> getItems() {
return items;
}
}
public static void main(String[] args) {
// 初始化商品
List<Product> products = new ArrayList<>(Arrays.asList(
new Product("P001", "苹果", 5.5, 100),
new Product("P002", "香蕉", 3.5, 150),
new Product("P003", "牛奶", 15.0, 80),
new Product("P004", "面包", 8.0, 60),
new Product("P005", "鸡蛋", 1.5, 200)
));
ShoppingCart cart = new ShoppingCart();
Scanner scanner = new Scanner(System.in);
while (true) {
System.out.println("\n=== 购物车系统 ===");
System.out.println("1. 查看商品列表");
System.out.println("2. 加入购物车");
System.out.println("3. 查看购物车");
System.out.println("4. 结算");
System.out.println("5. 退出");
System.out.print("请选择: ");
int choice = scanner.nextInt();
switch (choice) {
case 1:
System.out.println("\n=== 商品列表 ===");
for (Product p : products) {
System.out.println(p);
}
break;
case 2:
System.out.print("请输入商品编号: ");
String productId = scanner.next();
Product selected = null;
for (Product p : products) {
if (p.getId().equals(productId)) {
selected = p;
break;
}
}
if (selected == null) {
System.out.println("商品不存在");
break;
}
System.out.print("请输入数量: ");
int quantity = scanner.nextInt();
if (quantity <= 0 || quantity > selected.getStock()) {
System.out.println("无效数量或库存不足");
break;
}
cart.addItem(selected, quantity);
System.out.println("添加成功！");
break;
case 3:
cart.showCart();
break;
case 4:
cart.showCart();
if (!cart.getItems().isEmpty()) {
System.out.println("确认结算吗？(y/n)");
String confirm = scanner.next();
if (confirm.equalsIgnoreCase("y")) {
System.out.println("结算成功！总金额: " + cart.getTotalPrice());
cart.getItems().clear();
}
}
break;
case 5:
System.out.println("欢迎下次光临！");
return;
default:
System.out.println("无效选择");
}
}
}
}
设计建议
学习路线：
- 学生成绩系统 - 掌握基础语法和集合
- 银行账户系统 - 理解面向对象思想
- 日历记事本 - 学习文件操作
- GUI计算器 - 了解图形界面
- 购物车系统 - 综合应用
进阶优化方向：
- 加入数据库存储（MySQL/SQLite）
- 使用设计模式（工厂、单例等）
- 添加异常处理机制
- 实现用户登录注册
- 使用多线程处理并发访问
这些案例涵盖了Java开发的常见场景,通过实践能快速提升编程能力。
