"java语言中只有值传递，没有引用传递"的理解

public class Human {
    private int age;
    private int sex;//0-女，1-男
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public int getSex() {
        return sex;
    }
    public void setSex(int sex) {
        this.sex = sex;
    }
}

class HumanTest {

    @Test
    void test() {
        Human human=new Human();
        int age=human.getAge();
        addage(age);
        System.out.println(age);
        
        man(human);
        System.out.println(human.getAge());
        assert human.getSex()==1;
        
    }
    void man(Human human) {
        human.setAge(20);
        human.setSex(1);
    }
    void addage(int age) {
        age+=2;
    }
}

0
20