Question

我有一个扩展JFrame的gui类。我将JPanel分开以获取代码可读性。我从顶部面板定义了组合框，我想将它的选定项目访问到我的中心面板。我的中心面板是可点击的网格面板。如何从BoxListener事件中的组合框中访问所选项目？

我的代码在这里：

       //Gui ==================================================
    public class Gui extends JFrame  {

        final int WINDOW_WIDTH = 1000; // Window width in pixels
        final int WINDOW_HEIGHT = 800; // Window height in pixels

        private TopPanel topPanel;
        private CenterPanel centerPanel;

        public SchedulerGui() {
            // Display the title
            setTitle("Class Scheduler");

            setSize(WINDOW_WIDTH, WINDOW_HEIGHT);

            // specify action for the close button
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

            // Create border layout
            setLayout(new BorderLayout());

            // create the custom panels;
            topPanel = new TopPanel();
            centerPanel = new CenterPanel(15,7);

            // Add it to the content pane
            add(topPanel, BorderLayout.NORTH);
            add(centerPanel, BorderLayout.CENTER);

            setVisible(true);
        }


        public static void main(String args[]) {
            new Gui();
        }
    }


    //top panel =====================================================


    public class TopPanel extends JPanel {

        JLabel labelCurrentStatus;

        // create combo boxes
        public JComboBox nameBox;

        String[] listNameBox = { "Select Box”, “Box1”, “Box2”, “Box3”};

        String selectedNameBox = "";

        public TopPanel() {
            nameBox = new JComboBox(listNameBox);

            // Register an action listener 
            nameBox.addActionListener(new ComboBoxListener());

            // add the combo boxes into the content pane
            add(nameBox);
        }

        private class ComboBoxListener implements ActionListener {
            @Override
            public void actionPerformed(ActionEvent e) {
                selectedNameBox = (String) nameBox.getSelectedItem();
                labelCurrentStatus.setText(selectedNameBox);
            }
        }

    }


    //center panel ================================================
    // creates panel grids that is clickable

    public class CenterPanel extends JPanel {

        public CenterPanel(int row, int col) {

            setLayout(new GridLayout(row, col));
            setBorder(BorderFactory.createEmptyBorder(1, 1, 1, 1));

            for (int i = 0; i < row; i++) {
                for (int j = 0; j < col; j++) {
                    JPanel pan = new JPanel();

                    pan.setEnabled(true);
                    pan.setBackground(Color.WHITE);
                    pan.setPreferredSize(new Dimension(3, 3));
                    pan.setBorder(BorderFactory.createLineBorder(Color.BLACK));
                    // an exception to not click the top row and most left column headers
                    if (i != 0 && j != 0) {
                        pan.addMouseListener(new BoxListener()); // add a mouse listener to make the panels clickable
                    }
                    // set names for each panel for later use
                    pan.setName("PANEL_" + i + "_" + j);
                    add(pan);
                }

            }
        }

        //Class that defines what happens when a panel is clicked
        public static class BoxListener extends MouseAdapter
        {
            public void mouseClicked(MouseEvent me)
            {   
                  JPanel clickedBox =(JPanel)me.getSource(); 
                  clickedBox.setBackground(Color.RED); 

        // insert here the code defining what happens when a grid is clicked. 
// Need to access the value of the selected item from the combo box
            }
        }

    }

Answer 1

Well, I think you ran into this problem because your setup is flawed. The only way I see around this is creating a GetSelectedNameBox() method in that Top panel Class, and a set method in your Center panel class.

So in your Gui class you would do something like:

String temp=topPanel.getSelectedNamebox();

And then you would do centerPanel.setXXXX(temp);

You can see that in an effort to create a more readable code by splitting things up, it probably makes readability worse. Furthermore, this is not the proper use of getters and setters.

I would reconfigure, and put all your different JPanels in the same class. I would also focus on using anonymous classes, rather than inner classes, for your actionListeners. This will shorten up your code very much. And get rid of all the blank lines :P

如何访问一个JPanel的组件到另一个JPanel

1 个答案: