Java ，导入未解决，继承，内部 class

Question

最近求java编程，运行出错。请帮忙

有两个class，PersonTest.java：

 public class PersonTest {

  public static void main(String[] args) {
    Person person1=new Person("dummy","sdymmt","20","male","washington");
    System.out.println("Name: "+person1.getName());
    System.out.println("Surname: "+person1.getSurname());
    System.out.println("Age: "+person1.getAge());
    System.out.println("Gender:" +person1.getGender());
    System.out.println("Birthplace: "+person1.getBirthplace());
    Person person2= new Person(400);
    System.out.println("Income:"+person2.getX()+" mije leke");
    System.out.println("Tax:"+person2.Taksat()+" mije leke");
    Student student1= new Student("adsd","zedsdsadza");
    System.out.println("emri"+student1.getEmer());
}

}

还有Person.java :

public class Person {
    private String Name;
    private String Surname;
    private String Age;
    private String Gender;
    private String Birthplace;
    private double x;
    public Person()
    {

    }
    public Person(String Name, String Surname, String Age, String Gender, String Birthplace) {
        this.Name = Name;
        this.Surname = Surname;    
        this.Age = Age; 
        this.Gender = Gender;
        this.Birthplace = Birthplace;

    }

    public String getName() {
        return Name;
    }

    public String getSurname() {
        return Surname;
    }

    public String getAge() {
        return Age;
    }

    public String getGender() {
        return Gender;
    }

    public String getBirthplace() {
        return Birthplace;
    }

    public Person(double x) {
        this.x = x;
    }

    public double getX() {
        return x;
    }

    double Taksat() {
        return (0.1 * x);
    }

    public class Student extends Person {
        private String University;
        private String Faculty;

        public Student(String Universiteti, String Fakulteti) {
            super(Name, Surname, Age, Gender, Birthplace);
            this.Faculty = Fakulteti;
            this.University = Universiteti;
        }

        public String getFaculty() {
            return Faculty;
        }

        public String getUniversity() {
            return University;
        }
    }
}

两个class在同一个默认包中。如何解决测试 class 无法将内部 class 学生识别为 class.

的事实

Answer 1

因为没有学生class。因为它嵌套了，所以是 Person.Student

Answer 2

嵌套的非静态 class 被称为 Inner Classes 那些 classes 不能没有 Outer class（包裹它们）。

Java docs

An instance of InnerClass can exist only within an instance of OuterClass and has direct access to the methods and fields of its enclosing instance.

To instantiate an inner class, you must first instantiate the outer class. Then, create the inner object within the outer object with this syntax:

OuterClass.InnerClass innerObject = outerObject.new InnerClass();

尝试使用：

Person.Student student = person1.new Student(PARAMETERS);

重要标记：

当然，您应该高度重视这不是一个好的设计，因为您可能希望这个 classes 在 Person class 之外可见，但也因为 Person.Student继承自 Person，它已经包含了 Student class，它通常看起来像一个循环或圆圈关系，首先这通常不是一个好主意。

Java ，导入未解决，继承，内部 class

Java ,import not resolved,inheritance,inner class

java

inheritance

inner-classes