Java初学者练手项目推荐与代码案例 |21xrx.com

Java初学者练手项目推荐与代码案例

2023-06-18 01:33:58 深夜i -- --

Java初学者练手项目代码案例

作为一个Java初学者，不光要掌握基本语法，还需要多做练习项目提高自己的编程技能。在这篇文章中，我将为大家推荐几个适合Java初学者的练手项目，并提供一些简单的代码案例，帮助大家更好地理解。

1. 简单的计算器

这个项目比较简单，但是可以练习Java中的变量声明、控制语句和基本的算法知识。代码示例如下：


import java.util.Scanner;
public class Calculator {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.println("请输入两个数字：");
    double num1 = scanner.nextDouble();
    double num2 = scanner.nextDouble();
    System.out.println("请选择要进行的操作：");
    System.out.println("1. 加法");
    System.out.println("2. 减法");
    System.out.println("3. 乘法");
    System.out.println("4. 除法");
    int choice = scanner.nextInt();
    double result = 0;
    switch (choice) {
      case 1:
        result = num1 + num2;
        break;
      case 2:
        result = num1 - num2;
        break;
      case 3:
        result = num1 * num2;
        break;
      case 4:
        result = num1 / num2;
        break;
      default:
        System.out.println("输入错误！");
    }
    System.out.println("结果为：" + result);
  }
}

2. 学生信息管理系统

这个项目可以让你练习Java中的类和对象、数组、输入输出等基础知识。代码示例如下：


import java.util.Scanner;
public class StudentManagementSystem {
  public static void main(String[] args) {
    int maxStudents = 100;
    Student[] students = new Student[maxStudents];
    Scanner scanner = new Scanner(System.in);
    int choice = 0;
    while (choice != 5) {
      System.out.println("请选择要进行的操作：");
      System.out.println("1. 添加学生");
      System.out.println("2. 删除学生");
      System.out.println("3. 查询学生");
      System.out.println("4. 修改学生");
      System.out.println("5. 退出程序");
      choice = scanner.nextInt();
      scanner.nextLine();
      switch (choice) {
        case 1:
          System.out.println("请输入学生姓名：");
          String name = scanner.nextLine();
          System.out.println("请输入学生年龄：");
          int age = scanner.nextInt();
          System.out.println("请输入学生性别：");
          String gender = scanner.next();
          Student student = new Student(name, age, gender);
          students[Student.getCount()] = student;
          System.out.println("添加成功！");
          break;
        case 2:
          System.out.println("请输入要删除学生的姓名：");
          String deleteName = scanner.nextLine();
          boolean isDeleted = false;
          for (int i = 0; i < Student.getCount(); i++) {
            if (students[i].getName().equals(deleteName)) {
              students[i] = null;
              isDeleted = true;
            }
            if (isDeleted && i < Student.getCount() - 1) {
              students[i] = students[i + 1];
            }
          }
          if (isDeleted) {
            Student.decreaseCount();
            System.out.println("删除成功！");
          } else {
            System.out.println("该学生不存在！");
          }
          break;
        case 3:
          System.out.println("请输入要查询学生的姓名：");
          String searchName = scanner.nextLine();
          boolean isExist = false;
          for (int i = 0; i < Student.getCount(); i++) {
            if (students[i].getName().equals(searchName)) {
              System.out.println(students[i]);
              isExist = true;
            }
          }
          if (!isExist) {
            System.out.println("该学生不存在！");
          }
          break;
        case 4:
          System.out.println("请输入要修改学生的姓名：");
          String modifyName = scanner.nextLine();
          boolean isModified = false;
          for (int i = 0; i < Student.getCount(); i++) {
            if (students[i].getName().equals(modifyName)) {
              System.out.println("请输入修改后的学生姓名：");
              String newName = scanner.nextLine();
              students[i].setName(newName);
              System.out.println("请输入修改后的学生年龄：");
              int newAge = scanner.nextInt();
              students[i].setAge(newAge);
              System.out.println("请输入修改后的学生性别：");
              String newGender = scanner.next();
              students[i].setGender(newGender);
              isModified = true;
            }
          }
          if (isModified) {
            System.out.println("修改成功！");
          } else {
            System.out.println("该学生不存在！");
          }
          break;
        case 5:
          break;
        default:
          System.out.println("输入错误！");
      }
    }
  }
}
class Student {
  private static int count = 0;
  private String name;
  private int age;
  private String gender;
  public Student(String name, int age, String gender) {
    this.name = name;
    this.age = age;
    this.gender = gender;
    count++;
  }
  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 String getGender()
    return gender;
  
  public void setGender(String gender)
    this.gender = gender;
  
  public static int getCount()
    return count;
  
  public static void decreaseCount()
    count--;
  
  @Override
  public String toString() {
    return "姓名：" + name + "，年龄：" + age + "，性别：" + gender;
  }
}

3. 入门级图书管理系统

这个项目可以让你练习Java中的面向对象编程、文件IO、异常处理等进阶知识。代码示例如下：


import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;
public class BookManagementSystem {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    ArrayList
  books = new ArrayList<>();
 
    readFromFile(books);
    int choice = 0;
    while (choice != 4) {
      System.out.println("请选择要进行的操作：");
      System.out.println("1. 查看所有图书");
      System.out.println("2. 添加图书");
      System.out.println("3. 查找图书");
      System.out.println("4. 退出程序");
      choice = scanner.nextInt();
      scanner.nextLine();
      switch (choice) {
        case 1:
          displayBooks(books);
          break;
        case 2:
          System.out.println("请输入图书名称：");
          String name = scanner.nextLine();
          System.out.println("请输入图书作者：");
          String author = scanner.nextLine();
          System.out.println("请输入图书价格：");
          float price = scanner.nextFloat();
          Book book = new Book(name, author, price);
          books.add(book);
          System.out.println("添加成功！");
          break;
        case 3:
          System.out.println("请输入要查找的图书名称：");
          String searchName = scanner.nextLine();
          boolean isExist = false;
          for (Book b : books) {
            if (b.getName().equals(searchName)) {
              System.out.println(b);
              isExist = true;
            }
          }
          if (!isExist) {
            System.out.println("该图书不存在！");
          }
          break;
        case 4:
          writeToFile(books);
          break;
        default:
          System.out.println("输入错误！");
      }
    }
    scanner.close();
  }
  public static void displayBooks(ArrayList
  books) {
 
    for (Book b : books) {
      System.out.println(b);
    }
  }
  public static void readFromFile(ArrayList
  books) {
 
    File file = new File("books.txt");
    try {
      if (!file.exists()) {
        file.createNewFile();
      }
      BufferedReader reader = new BufferedReader(new FileReader(file));
      String line = null;
      while ((line = reader.readLine()) != null) {
        String[] data = line.split("\\|");
        String name = data[0];
        String author = data[1];
        float price = Float.parseFloat(data[2]);
        Book book = new Book(name, author, price);
        books.add(book);
      }
      reader.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
  public static void writeToFile(ArrayList
  books) {
 
    File file = new File("books.txt");
    try {
      if (!file.exists()) {
        file.createNewFile();
      }
      BufferedWriter writer = new BufferedWriter(new FileWriter(file));
      for (Book b : books) {
        writer.write(b.getName() + "|" + b.getAuthor() + "|" + b.getPrice());
        writer.newLine();
      }
      writer.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
    System.out.println("程序已退出！");
  }
}
class Book {
  private String name;
  private String author;
  private float price;
  public Book(String name, String author, float price) {
    this.name = name;
    this.author = author;
    this.price = price;
  }
  public String getName() {
    return name;
  }
  public String getAuthor() {
    return author;
  }
  public float getPrice() {
    return price;
  }
  @Override
  public String toString() {
    return "书名：" + name + "，作者：" + author + "，价格：" + price;
  }
}

以上就是三个适合Java初学者的练手项目，希望对大家有所帮助！

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