Java中public关键字用法详细讲解

// 文件：Person.java
public class Person {
    public String name;
    public int age;
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    public void sayHello() {
        System.out.println("Hello, my name is " + name + " and I'm " + age + " years old.");
    }
}
// 文件：Main.java
public class Main {
    public static void main(String[] args) {
        Person person = new Person("Alice", 25);
        person.sayHello(); // 输出：Hello, my name is Alice and I'm 25 years old.
    }
}

// 文件：MathUtils.java
public class MathUtils {
    public static int add(int a, int b) {
        return a + b;
    }
    public static int subtract(int a, int b) {
        return a - b;
    }
}
// 文件：Main.java
public class Main {
    public static void main(String[] args) {
        int result = MathUtils.add(10, 5);
        System.out.println("10 + 5 = " + result); // 输出：10 + 5 = 15
    }
}

// 文件：Car.java
public class Car {
    public String brand;
    public String model;
    public int year;
    public Car(String brand, String model, int year) {
        this.brand = brand;
        this.model = model;
        this.year = year;
    }
}
// 文件：Main.java
public class Main {
    public static void main(String[] args) {
        Car car = new Car("Toyota", "Camry", 2022);
        System.out.println("Brand: " + car.brand); // 输出：Brand: Toyota
        System.out.println("Model: " + car.model); // 输出：Model: Camry
        System.out.println("Year: " + car.year);   // 输出：Year: 2022
    }
}

// 文件：Person.java
public class Person {
    private String name;
    private int age;
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    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;
    }
}
// 文件：Main.java
public class Main {
    public static void main(String[] args) {
        Person person = new Person("Alice", 25);
        System.out.println("Name: " + person.getName()); // 输出：Name: Alice
        System.out.println("Age: " + person.getAge());   // 输出：Age: 25
        person.setName("Bob");
        person.setAge(30);
        System.out.println("Name: " + person.getName()); // 输出：Name: Bob
        System.out.println("Age: " + person.getAge());   // 输出：Age: 30
    }
}