JAVA类的设计与封装

```java
public class Student {
    private String name;
    private int age;
    private String gender;
 
    // 构造方法
    public Student(String name, int age, String gender) {
        this.name = name;
        this.age = age;
        this.gender = gender;
    }
 
    // getter和setter方法
    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;
    }
 
    // 其他方法
    public void displayInfo() {
        System.out.println("Name: " + name);
        System.out.println("Age: " + age);
        System.out.println("Gender: " + gender);
    }
}
```

```java
public class Main {
    public static void main(String[] args) {
        // 创建学生对象
        Student student = new Student("Alice", 20, "Female");
 
        // 调用方法显示学生信息
        student.displayInfo();
 
        // 修改学生信息
        student.setAge(21);
        student.setGender("Male");
 
        // 再次显示学生信息
        student.displayInfo();
    }
}
```