How to read objects of arrays from a .txt file? - arrays

Question

First what i have done is write an ArrayList as ann object to a .txt file, what I am trying to do is read back those objects into an array and display the array(reverse of first step). The arraylist i'm passing to the funnctions are salesman and technicians that extend employees with parameters name,number,target,terriorty etc. I get this error when i try to compile it.
Exception in thread "main" java.lang.ClassCastException: java.util.ArrayList cannot be cast to Employee
at FileIO.readObject(FileIO.java:165)
at UseCompany.main(UseCompany.java:61)
Trying to read back objects from text file
ArrayList<Employee> use_company_arraylist2 = FileIO.("C:\\Users\\Saad\\Documents\\writeObjectMethod.txt"");
use_company_arraylist2 = FileIO.readObject("C:\\Users\\Saad\\Documents\\writeObjectMethod.txt");
The writing object to text file code:
public static void writeObject(ArrayList<Employee> array_of_employee, String filename)
{
try{
//create file stream and write array to file using stream using objectoutput stream
FileOutputStream fle = new FileOutputStream("c:\\Users\\Saad\\Documents\\writeObjectMethod.txt");
ObjectOutputStream oos = new ObjectOutputStream(fle);
oos.writeObject(array_of_employee);
oos.close();
fle.close();
}
catch(FileNotFoundException filenotfound)
{
System.out.println("FILE NOTE FOUND");
}
catch(IOException ioerror)
{
System.out.println("input or output error");
}
}//end writeObject
The reading object from text file code:
public static ArrayList<Employee> readObject (String filename)
{
ArrayList<Employee> newArrayList = new ArrayList<Employee>();
try
{
FileInputStream readfle = new FileInputStream(filename);
ObjectInputStream readobjectfile = new ObjectInputStream(new BufferedInputStream(readfle));
newArrayList.add((Employee)readobjectfile.readObject());
}
catch(ClassNotFoundException clasnfd)
{
System.out.println("class error?");
}
catch(IOException ioerror)
{
System.out.println("input or output error");
}
return newArrayList;
}//end readObject

Answer 1

An object of type Arraylist can't be casted to an object of Employee class.
This will work
ArrayList list = new ArrayList();
list.add(new Employee());
// for writing arraylist object to file
new ObjectOutputStream(new FileOutputStream(new File("a.txt"))).writeObject(list);
// for reading array list from file
ArrayList<Employee> anotherList = (ArrayList<Employee>) new ObjectInputStream(new FileInputStream(new File("a.txt"))).readObject();
System.out.println(anotherList.size());