How to read Arraylist to a file and read it?

Question

i have some Class : Student, Teacher, Main and SaveRead
in finally i want save and read an array list like this [Teacher1 [Student1, 101], [Student2, 101], Teacher2 [Student1, 101], [Student2, 101]] to a file with code below. but has some Errors.

public class SaveRead implements Serializable
{
Scanner vorodi = new Scanner(System.in);
private static final String PATH = "D:/teachers.txt";

public void saveFile(ArrayList<Teacher> teachers)
throws IOException
{
try (ObjectOutputStream os = new ObjectOutputStream(new FileOutputStream(PATH))) {
os.writeObject(teachers);
}
}
public ArrayList<Teacher> readFile()
throws ClassNotFoundException, IOException
{
try (ObjectInputStream is = new ObjectInputStream(new FileInputStream(PATH))) {
return (ArrayList<Teacher>) is.readObject();
}
}
}

and Error:
Exception in thread "main" java.io.NotSerializableException: university.Teacher
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at java.util.ArrayList.writeObject(ArrayList.java:762)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:1028)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1496)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1432)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1178)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:348)
at university.SaveRead.saveFile(SaveRead.java:23)
at university.SchoolManager.main(SchoolManager.java:27)
Java Result: 1

Answer 1

Is Teacher class serializable?