课程进度 33% · 第4/10章第4/10章 · 标签 1/3
— 1 —
类的定义
Java 是纯粹的面向对象语言，类是对现实事物的抽象。通过封装数据和方法，实现高内聚低耦合的设计。
```java
public class Student {
private String name;
private int age;
private double score;
public Student(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() { return name; }
public void setName(String name) { this.name = name; }
public void study() {
System.out.println(name + " 正在学习");
}
}
// 使用
Student s = new Student("Alice", 20);
s.study();
s.setName("Bob");
```
java
1
public class Student {
2
private String name;
3
private int age;
4
private double score;
5
6
public Student(String name, int age) {
7
this.name = name;
8
this.age = age;
9
}
10
11
public String getName() { return name; }
12
public void setName(String name) { this.name = name; }
13
14
public void study() {
15
System.out.println(name + " 正在学习");
16
}
17
}
18
19
// 使用
20
Student s = new Student("Alice", 20);
21
s.study();
22
s.setName("Bob");
— 2 —
封装与访问控制
```java
// 访问修饰符
public class Person {
public String name; // 所有类可访问
protected int age; // 子类+同包
String address; // 默认：同包
private double salary; // 仅本类
// Getter/Setter
public double getSalary() { return salary; }
public void setSalary(double s) { salary = s; }
// 静态成员
public static int count = 0;
public static void showCount() {
System.out.println(count);
}
}
```
java
1
// 访问修饰符
2
public class Person {
3
public String name; // 所有类可访问
4
protected int age; // 子类+同包
5
String address; // 默认：同包
6
private double salary; // 仅本类
7
8
// Getter/Setter
9
public double getSalary() { return salary; }
10
public void setSalary(double s) { salary = s; }
11
12
// 静态成员
13
public static int count = 0;
14
public static void showCount() {
15
System.out.println(count);
16
}
17
}
📖封装的核心原则：隐藏内部实现，暴露必要接口。使用 private 保护数据，通过 public 方法提供安全访问