Java - compilation error debug -

i have compilation error can't seem fix. gives me message type mismatch: cannot convert object list. below have added methods says error in.

// read books file     public void readbooksfromfile() {         if(booksdatabase != null && !booksdatabase.isempty()) {             try (objectinputstream input = new objectinputstream(new fileinputstream(booksdatabase))) {                 books = input.readobject(); // error here             } catch (ioexception e) {                 e.printstacktrace();                             }         }     } 

the second method

public listbook(string booksdatabase) {         this.booksdatabase = booksdatabase;         readbooksfromfile(); // error here     } 

the third method

public static void main (string[] args){         // creates listbook object keep track of books in library         listbook lb = new listbook("books.dat"); // error here          // add books listbook object         lb.addbook(new book("e-commerce", "kenneth laudon", "2014", "024449"));         lb.addbook(new book("java programming", "daniel liang", "2014", "761312"));         lb.addbook(new book("eu internet law", "andrej savin", "2015", "429379"));            //new object          //getter setter methods          librarianmenu li = new librarianmenu(lb);          //execute function librarian.java      } 

how fix error?

objectinputstream returns object; you're assigning books, of type list. bad idea.

worse, think you're imagining readobject can iterate on collection , read multiple books list. think should write method reads single book , iterate on collection, adding individual books list.