继承的一点疑问，javap分析字节码

Question

Student.java
class Person
{
public int age;
public String name;
public Person(int age,String name){
this.setAge(age);
this.setName(name);
}
public void info(){
System.out.println("sdflksdj");
}
public void setAge(int age){
this.age=age;
}
public void setName(String name){
this.name=name;
}
public int getAge(){
return this.age;
}
public String getName(){
return this.name;
}
}
public class Student extends Person
{
public String school;
public Student(int age,String name,String school){
super(age,name);
this.setSchool(school);
}
public void setSchool(String school){
this.school=school;
}
public String getSchool(){
return this.school;
}
}
编译：javac Student.java
分析字节码：javap -c -private Student.java
Compiled from "Student.java"
public class Student extends Person {
  public java.lang.String school;  public Student(int, java.lang.String, java.lang.String);
    Code:
       0: aload_0
       1: iload_1
       2: aload_2
       3: invokespecial #1                  // Method Person."<init>":(ILjava/la
ng/String;)V
       6: aload_0
       7: aload_3
       8: invokevirtual #2                  // Method setSchool:(Ljava/lang/Stri
ng;)V
      11: return  public void setSchool(java.lang.String);
    Code:
       0: aload_0
       1: aload_1
       2: putfield      #3                  // Field school:Ljava/lang/String;
       5: return  public java.lang.String getSchool();
    Code:
       0: aload_0
       1: getfield      #3                  // Field school:Ljava/lang/String;
       4: areturn  public java.lang.String getName();
    Code:
       0: aload_0
       1: invokespecial #4                  // Method Person.getName:()Ljava/lan
g/String;
       4: areturn  public int getAge();
    Code:
       0: aload_0
       1: invokespecial #5                  // Method Person.getAge:()I
       4: ireturn  public void setName(java.lang.String);
    Code:
       0: aload_0
       1: aload_1
       2: invokespecial #6                  // Method Person.setName:(Ljava/lang
/String;)V
       5: return  public void setAge(int);
    Code:
       0: aload_0
       1: iload_1
       2: invokespecial #7                  // Method Person.setAge:(I)V
       5: return  public void info();
    Code:
       0: aload_0
       1: invokespecial #8                  // Method Person.info:()V
       4: return
}
如果我把声明Studnet类的的public去掉
编译：javac Student.java 通过
分析字节码：javap -c -private Student
则：
Compiled from "Student.java"
class Student extends Person {
  public java.lang.String school;  public Student(int, java.lang.String, java.lang.String);
    Code:
       0: aload_0
       1: iload_1
       2: aload_2
       3: invokespecial #1                  // Method Person."<init>":(ILjava/la
ng/String;)V
       6: aload_0
       7: aload_3
       8: invokevirtual #2                  // Method setSchool:(Ljava/lang/Stri
ng;)V
      11: return  public void setSchool(java.lang.String);
    Code:
       0: aload_0
       1: aload_1
       2: putfield      #3                  // Field school:Ljava/lang/String;
       5: return  public java.lang.String getSchool();
    Code:
       0: aload_0
       1: getfield      #3                  // Field school:Ljava/lang/String;
       4: areturn
}就去掉了一个public，怎么会有这样的区别？？？？
很是纳闷，去掉public后，从分析的字节码来看，好像Studnet类没有继承Person类（当然是继承了）
但是没去掉public之前，明显看出是继承了Person类，希望能从根本上给解答一下。

Answer 1

源代码Student.javaclass Person
{
public int age;
public String name;
public Person(int age,String name){
this.setAge(age);
this.setName(name);
}
public void info(){
System.out.println("sdflksdj");
}
public void setAge(int age){
this.age=age;
}
public void setName(String name){
this.name=name;
}
public int getAge(){
return this.age;
}
public String getName(){
return this.name;
}
}
class Student extends Person
{
public String school;
public Student(int age,String name,String school){
super(age,name);
this.setSchool(school);
}
public void setSchool(String school){
this.school=school;
}
public String getSchool(){
return this.school;
}
}

Answer 2

javap -c -private Studnet以下是分析的字节码内容：（没去掉Studnet类前面的public之前）
Compiled from "Student.java"
public class Student extends Person {
  public java.lang.String school;  public Student(int, java.lang.String, java.lang.String);
    Code:
       0: aload_0
       1: iload_1
       2: aload_2
       3: invokespecial #1                  // Method Person."<init>":(ILjava/
ng/String;)V
       6: aload_0
       7: aload_3
       8: invokevirtual #2                  // Method setSchool:(Ljava/lang/St
ng;)V
      11: return  public void setSchool(java.lang.String);
    Code:
       0: aload_0
       1: aload_1
       2: putfield      #3                  // Field school:Ljava/lang/String;
       5: return  public java.lang.String getSchool();
    Code:
       0: aload_0
       1: getfield      #3                  // Field school:Ljava/lang/String;
       4: areturn  public java.lang.String getName();
    Code:
       0: aload_0
       1: invokespecial #4                  // Method Person.getName:()Ljava/l
g/String;
       4: areturn  public int getAge();
    Code:
       0: aload_0
       1: invokespecial #5                  // Method Person.getAge:()I
       4: ireturn  public void setName(java.lang.String);
    Code:
       0: aload_0
       1: aload_1
       2: invokespecial #6                  // Method Person.setName:(Ljava/la
/String;)V
       5: return  public void setAge(int);
    Code:
       0: aload_0
       1: iload_1
       2: invokespecial #7                  // Method Person.setAge:(I)V
       5: return  public void info();
    Code:
       0: aload_0
       1: invokespecial #8                  // Method Person.info:()V
       4: return
}

Answer 3

去掉Studnet类的public之后编译成功
用javap -c -private再次分析
javap -c -private StudentCompiled from "Student.java"
class Student extends Person {
  public java.lang.String school;  public Student(int, java.lang.String, java.lang.String);
    Code:
       0: aload_0
       1: iload_1
       2: aload_2
       3: invokespecial #1                  // Method Person."<init>":(ILjava/la
ng/String;)V
       6: aload_0
       7: aload_3
       8: invokevirtual #2                  // Method setSchool:(Ljava/lang/Stri
ng;)V
      11: return  public void setSchool(java.lang.String);
    Code:
       0: aload_0
       1: aload_1
       2: putfield      #3                  // Field school:Ljava/lang/String;
       5: return  public java.lang.String getSchool();
    Code:
       0: aload_0
       1: getfield      #3                  // Field school:Ljava/lang/String;
       4: areturn
}

Answer 4

哪里看出去掉public之后不是明显继承呢，不是还是有extends吗

Answer 5

javap -c  Student
试试

Answer 6

你理解错了 
我的意思是说对于Student.java文件，去掉Student类前的public前后用javap分析一下出来的结果不一样，去掉后，父类的方法没有在子类中体现，我是这个意思，这个什么原因呢

Answer 7

要注意的重点在于：
Person类的访问修饰为默认访问(即包内可见，等同于C++的访问修饰符friendly，由于在下的习惯问题，下面提到的friendly都是指Java的默认访问)。由于Person类本身是friendly的缘故，其定义的函数info等虽然修饰符为public，但实际的可见范围也是friendly。这时用一public的类Student去继承Person类，无意中扩大了info等函数的可见范围。因此在Student类的代码中要包含可见范围被扩大的info等函数的代码。1、将Student类也定义为friendly
2、将Person类定义为public
3、将info等函数定义为friendly或可见范围更小的private
以上三种情况都不会造成函数可见范围扩大，子类Student中也不必包含父类Person中定义的函数代码了。

Answer 8

试了几下发现貌似必须是 继承自父类的方法访问控制符在子类中必须是public才能在javap -c -private下显示（但未找到官方文件确认）子类是package-private时，如9楼所说，父类的public方法继承到子类中合成效果不是public，所以未显示