public class Car {
    private String color; // 實例變量

    public void setColor(String color) { // 參數(shù)與實例變量同名
        this.color = color; // this.color 是實例變量，color 是參數(shù)
    }

    public String getColor() {
        return this.color; // 顯式使用 this 訪問實例變量
    }

    public static void main(String[] args) {
        Car car = new Car();
        car.setColor("Blue");
        System.out.println(car.getColor()); // 輸出: Blue
    }
}

public class Car {
    private String color;
    private int year;

    public Car(String color) {
        this.color = color;
        this.year = 2023; // 默認年份
    }

    public Car(String color, int year) {
        this(color); // 調(diào)用單參數(shù)構(gòu)造器
        this.year = year; // 覆蓋默認年份
    }

    public void printDetails() {
        System.out.println("Color: " + color + ", Year: " + year);
    }

    public static void main(String[] args) {
        Car car1 = new Car("Red");
        Car car2 = new Car("Blue", 2020);
        car1.printDetails(); // 輸出: Color: Red, Year: 2023
        car2.printDetails(); // 輸出: Color: Blue, Year: 2020
    }
}

public class Car {
    public void startEngine() {
        Engine engine = new Engine();
        engine.start(this); // 將當前 Car 對象傳遞給 Engine
    }

    public String toString() {
        return "A Car";
    }
}

class Engine {
    public void start(Car car) {
        System.out.println("Starting " + car); // 輸出: Starting A Car
    }
}

public class Main {
    public static void main(String[] args) {
        Car car = new Car();
        car.startEngine();
    }
}

public class Car {
    private String color;
    private int year;

    public Car setColor(String color) {
        this.color = color;
        return this; // 返回當前對象
    }

    public Car setYear(int year) {
        this.year = year;
        return this; // 返回當前對象
    }

    public void printDetails() {
        System.out.println("Color: " + color + ", Year: " + year);
    }

    public static void main(String[] args) {
        Car car = new Car()
            .setColor("Green")
            .setYear(2021);
        car.printDetails(); // 輸出: Color: Green, Year: 2021
    }
}

public class Car {
    private String color = "White";

    public static void printSomething() {
        // System.out.println(this.color); // 錯誤: 靜態(tài)方法中不能使用 this
        System.out.println("This is a static method.");
    }

    public static void main(String[] args) {
        Car.printSomething(); // 輸出: This is a static method.
    }
}

public class Person {
    private String name;
    private int age;

    // 構(gòu)造器1：只設置姓名
    public Person(String name) {
        this.name = name;
        this.age = 0; // 默認年齡
    }

    // 構(gòu)造器2：設置姓名和年齡，調(diào)用構(gòu)造器1
    public Person(String name, int age) {
        this(name); // 調(diào)用單參數(shù)構(gòu)造器
        this.age = age;
    }

    // 支持鏈式調(diào)用的 setter 方法
    public Person setName(String name) {
        this.name = name;
        return this;
    }

    public Person setAge(int age) {
        this.age = age;
        return this;
    }

    // 使用 this 訪問實例變量
    public void introduce() {
        System.out.println("Hi, I'm " + this.name + " and I'm " + this.age + " years old.");
    }

    public static void main(String[] args) {
        // 使用鏈式調(diào)用
        Person person1 = new Person("Alice").setAge(30);
        person1.introduce(); // 輸出: Hi, I'm Alice and I'm 30 years old.

        // 使用多參數(shù)構(gòu)造器
        Person person2 = new Person("Bob", 25);
        person2.introduce(); // 輸出: Hi, I'm Bob and I'm 25 years old.
    }
}