可访问和可修改的数据？

Question

就从课外的可访问性而言，可变等级中的可访问数据和可修改数据有什么区别？

这是我在课堂外调用grade方法的代码：

package studenttester;

public class student {

    private String name;
    private int age;
    private String grade;
    private double average;
    private boolean disability;
    
    
    private void printStudentInfo(){ //Data Encapsulation is methods of the public interface provide access to private data, while hiding implementation. 

        System.out.println("Name: "+name+",Age: "+age+",Grade: "+grade+",Average: "+average +" Disability: "+disability);
    } 
    
    public void setGrade(String newGrade){
        grade=newGrade;
    }
    
    public String getGrade(){
        return grade;
    }
 }
    public class StudentTester{
public static void main(String[] args){
       student S1 = new student(); 
       student S2 = new student(); 

       S1.setGrade("11");
       System.out.println("Student one: " +S1.getGrade()+", Student two: "+S2.getGrade());

       /* The instance variables are name, age, grade, average, disability and those are the variables that the object S2 contains. The object’s attributes are : name, age, grade, average, disability. 

       S1 attributes values : name: null , age:0, grade:"11", average : 0.0, disability: false
       S2 attributes values : name: null , age:0, grade:null, average : 0.0, disability: false */

}
}

Answer 1

等级是private，因此就学生班级之外的直接可访问性而言，它是不可访问的。因此，如果我们有一个 Student 类型的变量 s1，那么尝试 s1.grade 将不起作用。虽然，由于我们有一个public getter 方法getGrade，它实际上可以被其他类访问。修改也一样，所以在课堂外没有s1.grade = "11";，但你可以做s1.setGrade("11")。

Answer 2

可访问的数据意味着您只能访问。我们只能查看或访问无法修改或更改的数据

而 modifiable 可以修改或更改。

您可以说可访问的数据是常量，而可修改的数据是变量