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Thread: Creating a Library, abstract class created issues. Also need GUI help.

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    Question Creating a Library, abstract class created issues. Also need GUI help.

    I am still in my first few months of programming so please bear with me if the problems are stupid-easy to fix.

    When I changed the the Books file to an Abstract class, it created a few compatibility issues. I fixed most, but there are still a couple of errors that I can't wrap my head around.

    Also, when I list the books, it doesn't show in the GUI, and also errors should show in a JOptionPane I guess, not sure. :/

    Help would be greatly appreciated! Hope to have a positive first experience on this website
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    Default Re: Creating a Library, abstract class created issues. Also need GUI help.

    Please post the code you are working on here on the forum.
    there are still a couple of errors
    Please copy the full text of the error messages and paste it here.

    Be sure to wrap your code with code tags:
    [code=java]
    <YOUR CODE HERE>
    [/code]
    to get highlighting and preserve formatting.
    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Creating a Library, abstract class created issues. Also need GUI help.

    First error: no suitable method found for add(StringTokenizer)
    	//READ FROM FILE
    	public void LibraryRead()
    	{
    		libraryBooks.clear();
     
    	   	try
    	   	{
    	     	FileReader fr = new FileReader("Library.txt");
    	    	BufferedReader br = new BufferedReader(fr);
     
    	     	String stringRead = br.readLine();
     
    	     	while( stringRead != null )
    	     	{
    	       		StringTokenizer st = new StringTokenizer(stringRead, ", ");
     
    	       	   	String title = st.nextToken();
    	       		String author = st.nextToken();
    	       		String form = st.nextToken();
     
    	       		libraryBooks.add(st); //ERROR LINE
     
    	      		stringRead = br.readLine();
    	     	}
    	     	br.close();
    	   	}
     
    	   	catch(FileNotFoundException fnfe)
    	   	{
     
    	     	System.out.println("ERROR: Unable to find Library.txt");
    	   	}
     
    	   	catch(IOException ioe)
    	   	{
    	     	ioe.printStackTrace();
    	   	}
    	}


    Second error: Book is abstract; cannot be instantiated
    	//WRITE TO FILE
    	public void LibraryWrite (String title, String author, String form)
    	{
    		boolean bookExists = false;
     
    	  	try
    	   	{
    	       	Scanner scan = new Scanner( System.in );
     
    		FileWriter fw = new FileWriter( "Library.txt", true);
    	       	BufferedWriter bw = new BufferedWriter(fw);
     
    	       	ArrayList<Books> LibraryWrite = new ArrayList<Books>();
    	       	LibraryRead();
     
    			for(Books checkBooks : libraryBooks)
    			{
    				if(checkBooks.getTitle().equals(title) &&   checkBooks.getAuthor().equals(author))
    				{
    					bookExists = true;
    				}
    			}
     
    			if(bookExists)
    			{
    				System.out.println("ERROR: Book already exists.");
    			}
     
    			else
    			{
    				Books newBook2 = new Books(title, author, form); //ERROR LINE
    				LibraryWrite.add(newBook2);
     
    				for (Books book : LibraryWrite)
    				{
    					bw.write(book.getTitle() + ", " + book.getAuthor() + ", " + book.getForm() + "\r\n");
    					System.out.println(book);
    				}
    				bw.close();
     
    	        	System.out.println("SUCCESS! File has been written.");
    			}
    		}
     
    	   	catch( IOException ioe )
    	   	{
    	      	ioe.printStackTrace( );
    	   	}
    	}

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    Default Re: Creating a Library, abstract class created issues. Also need GUI help.

    no suitable method found for add(StringTokenizer)
    The compiler could not find an add() method that took a StringTokenizer object as an arg.

    Book is abstract; cannot be instantiated
    You can not create an instance of an abstract class.
    If you don't understand my answer, don't ignore it, ask a question.

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