Is it possible to change the object type of an array list i.e. from an Object ArrayList to a specific object ArrayList. I have tried using a for each. Alternatively is there a way to change the filehandling method such that it can return a specific type depending on which file it reads from without duplicating code?
My Attempt:
ArrayList<Object> librarianList = FileHandling.getLibrarianRecords(fileName);
ArrayList<Librarian> libList = new ArrayList<>();
for (Object addType: librarianList) {
libList.add(addType);
}
getLibrarianRecords code
public static ArrayList<Object> getLibrarianRecords(String filename){
ArrayList<Object> fromFile = new ArrayList<>(); //Array of
// existing librarians
try{
FileInputStream fIS =
new FileInputStream(SYSTEM_PATH + filename);
ObjectInputStream oIS = new ObjectInputStream(fIS);
fromFile = (ArrayList<Object>)oIS.readObject();
} catch (IOException ex){
System.out.println("Failed to read from file " + ex.getMessage());
ex.printStackTrace(); //Catches an IO exception.
} catch (ClassNotFoundException ex){
System.out.println("Error class not found" + ex.getMessage());
ex.printStackTrace(); //Catches a class not found
// exception.
}
return fromFile; //Returns the array list.
}
Thanks to @user3170251 for suggesting casting
ArrayList<Object> librarianList = FileHandling.getLibrarianRecords(fileName);
ArrayList<Librarian> libList = new ArrayList<>();
for (Object addType: librarianList) {
libList.add((Librarian) addType);
}
For changing the type this does work.