5.4.3 封装的使用细节 ​

public class Person {
	// 属性一般使用private修饰
	private String name;
	private int age;
	private boolean flag;
	// 为属性提供public修饰的set/get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 boolean isFlag() { // 注意：boolean类型的属性get方法是is开头的
		return flag;
	}
	public void setFlag(boolean flag) {
		this.flag = flag;
	}
}

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

	}
	public Person(String name, int age) {
		this.name = name;
		// this.age = age; // 构造方法中不能直接赋值，应该调用setAge方法
		setAge(age);
	}
	
	public void setName(String name) {
		this.name = name;
	}
	public String getName() {
		return name;
	}
	public void setAge(int age) {
		// 在赋值之前先判断年龄是否合法
		if (age > 130 || age < 0) {
			this.age = 18;  // 不合法赋默认值18
		} else {
			this.age = age; // 合法才能赋值给属性age
		}
	}
	public int getAge() {
		return age;
	}
	@Override
	public String toString() {
		return "Person [name=" + name + ", age=" + age + "]";
	}
}

public class Test2 {
	public static void main(String[] args) {
		Person p1 = new Person();
		// p1.name = "小红"; // 编译错误
		// p1.age = -45;    // 编译错误
		p1.setName("小红");
		p1.setAge(-45);
		System.out.println(p1);
		
		Person p2 = new Person("小白", 300);
		System.out.println(p2);
	}
}