java

Question

我对静态变量的序列化有点困惑，因为它们不能序列化。虽然singleton类对象可以序列化。     我有一个示例代码：

1. 在TestSerilization类中：我首先编译了一个运行代码而没有 评论我得到了结果，但正如我评论部分并重新编译 并运行我没有获得静态字符串值的所需结果 而反序列化

2. 在TestSerilization2类中：我首先编译运行代码没有注释我得到了结果，但是当我评论部分和 重新编译和运行我确实得到了私有静态相同的结果 反序列化时的学生实例值。

   我想问一下为什么private static Student实例提供了值但私有static String name没有，尽管两者都是static。

    import java.io.*;
    class Student implements Serializable{
        private static String  name;
        private int rollNo;

        public void setName(String name){
            this.name=name;
        }
        public String getName(){
            return this.name;
        }

        public void setRollNo(int rollNo){
            this.rollNo=rollNo;
        }
        public int getRollNo(){
            return this.rollNo;
        }
    }
    public class TestSerilization{
        public static void main(String args[]) throws FileNotFoundException, IOException, ClassNotFoundException{
            /*
            Student s1=new Student();
            s1.setName("Apoorv");
            s1.setRollNo(13);

            ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream("D:\\JAVA Practice\\output.ser"));
            oos.writeObject(s1);
            System.out.println("s1: name-"+s1.getName()+" rollno-"+s1.getRollNo()+" hascode: "+s1.hashCode());
            */
            ObjectInputStream ins=new ObjectInputStream(new FileInputStream("D:\\JAVA Practice\\output.ser"));
            Student s2=(Student)ins.readObject();
            System.out.println("s2: name-"+s2.getName()+" rollno-"+s2.getRollNo()+" hascode: "+s2.hashCode());
        }
    }




    import java.io.*;
    final class Student implements Serializable{
        private static Student instance;
        private String  name;
        private int rollNo;

        private Student(){} 
        public static Student getInstance(){
            if(instance==null){
                instance=new Student();
            }
            return instance;
        }

        public void setName(String name){
            this.name=name;
        }
        public String getName(){
            return this.name;
        }

        public void setRollNo(int rollNo){
            this.rollNo=rollNo;
        }
        public int getRollNo(){
            return this.rollNo;
        }
    }
    public class TestSerilization2{
        public static void main(String args[]) throws FileNotFoundException, IOException, ClassNotFoundException{
            /*
            Student s1=Student.getInstance();
            s1.setName("Apoorv");
            s1.setRollNo(13);
            System.out.println("s1: name-"+s1.getName()+" rollno-"+s1.getRollNo()+" hascode: "+s1.hashCode());
            Student s2=Student.getInstance();
            System.out.println("s2: name-"+s2.getName()+" rollno-"+s2.getRollNo()+" hascode: "+s2.hashCode());
            */

            /*
            Student s1=Student.getInstance();
            s1.setName("Apoorv");
            s1.setRollNo(13);

            ObjectOutputStream oos=new ObjectOutputStream(new FileOutputStream("D:\\JAVA Practice\\output2.ser"));
            oos.writeObject(s1);
            System.out.println("s1: name-"+s1.getName()+" rollno-"+s1.getRollNo()+" hascode: "+s1.hashCode());
            */
            ObjectInputStream ins=new ObjectInputStream(new FileInputStream("D:\\JAVA Practice\\output2.ser"));
            Student s2=(Student)ins.readObject();
            System.out.println("s2: name-"+s2.getName()+" rollno-"+s2.getRollNo()+" hascode: "+s2.hashCode());

        }
    }