Adding a private field to a class in Java

Question

I have two relevant classes SpaceInvadersApp and HighScoreTableModel

I need to Add a new private field to the SpaceInvadersApp class of type HighScoreTableModel, and initialise this fi eld at the beginning of the SpaceInvadersApp constructor.

This is my attempt I think I am not doing it correctly.

public class SpaceInvadersApp extends JFrame {

/**
 * 
 */
private static final long serialVersionUID = 1L;

private final GamePanel game;

private HighScoreTableModel highScoreTableModel; // unsure about this

final private JMenuItem menuItemGamePause;

/**
 * Create new Space Invaders application.
 * @throws HeadlessException 
 */
public SpaceInvadersApp() throws HeadlessException {

    highScoreTableModel = new HighScoreTableModel("Name", "Score"); //unsure about this

Heres the relevent code from the HighScoreTableModel class

package spaceinvaders.highscores;

import java.util.*;
import javax.swing.event.*;
import javax.swing.table.*;

public class HighScoreTableModel implements TableModel {


private List<String> col1StringList = new ArrayList<String>();
private List<Integer> col2IntegerList = new ArrayList<Integer>();
private String col1Name, col2Name;

private List<TableModelListener> listenerList = new ArrayList<TableModelListener>();

public HighScoreTableModel(String col1Name, String col2Name) {
    this.col1Name = col1Name;
    this.col2Name = col2Name;

Answer 1

Consider looking the packages of this classes, the need to be at the same package or imported.

Another detail is your variable menuItemGamePause , it needs to be initialized since it is final .

final private JMenuItem menuItemGamePause = new JMenuItem();