java 对话框 inheritance 是如何工作的？ 我失去了一些财产

Question

Sorry I don't have much knowledge about Java or swing applications. I created a dialog called DlgShape and in it i have 2 text fields, 2 buttons and 2 labels. I tried creating DlgRectangle and instead of it inheriting from JDialog I inherited from DlgShape. The design of the parent and child class are identical but in the DlgRectangle I don't have the labels, buttons and text fields listed out as properties, I have public get and set methods and getContentPane. Suddenly my layout of the DlgRectangle changed from GridBagLayout to BorderLayout, why did it do that? I have the default DlgShape constructor set the layout to GridBagLayout and my DlgRectangle constructor also calls the super constructor.

I tried manually typing the code to create a label and put it in the content panel but it doesn't appear. I had a thought that maybe I need to get the content panel to be a property of DlgShape and maybe make it protected.

Here's my code for DlgShape: package drawing;

public class DlgShape extends JDialog {

    private final JPanel contentPanel = new JPanel();
    private boolean validInput;
    private JTextField txtX;
    private JTextField txtY;
    private JButton btnOuterColor = new JButton("outer color");
    private JButton btnInnerColor = new JButton("inner color");
    JLabel lblX = new JLabel("X");
    
    private Shape shape;
    
    private void setShape(Shape shape) {
        this.shape=shape;
    }
    
    private Shape getShape(Shape shape) {
        return shape;
    }
    
    public void setValidInput(boolean validInput) {
        this.validInput=validInput;
    }
    
    public boolean isValidInput() {
        return this.validInput;
    }
    
    public JTextField getTxtX() {
        return txtX; 
    }
    public JTextField getTxtY() {
        return txtY; 
    }

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            DlgShape dialog = new DlgShape();
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setVisible(true);
            
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Create the dialog.
     */
    public DlgShape() {
        setModal(true);
        setBounds(100, 100, 233, 300);
        
        
        //Auto generated
        getContentPane().setLayout(new BorderLayout());
        contentPanel.setBorder(new EmptyBorder(5, 5, 5, 5));
        getContentPane().add(contentPanel, BorderLayout.CENTER);
        GridBagLayout gbl_contentPanel = new GridBagLayout();
        gbl_contentPanel.columnWidths = new int[]{0, 0, 0};
        gbl_contentPanel.rowHeights = new int[]{0, 0, 0, 0, 0, 0, 0, 0, 0};
        gbl_contentPanel.columnWeights = new double[]{0.0, 1.0, Double.MIN_VALUE};
        gbl_contentPanel.rowWeights = new double[]{0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, Double.MIN_VALUE};
        contentPanel.setLayout(gbl_contentPanel);
        {
            
            GridBagConstraints gbc_lblX = new GridBagConstraints();
            gbc_lblX.anchor = GridBagConstraints.EAST;
            gbc_lblX.insets = new Insets(0, 0, 5, 5);
            gbc_lblX.gridx = 0;
            gbc_lblX.gridy = 0;
            contentPanel.add(lblX, gbc_lblX);
        }
        {
            txtX = new JTextField();
            GridBagConstraints gbc_txtX = new GridBagConstraints();
            gbc_txtX.insets = new Insets(0, 0, 5, 0);
            gbc_txtX.fill = GridBagConstraints.HORIZONTAL;
            gbc_txtX.gridx = 1;
            gbc_txtX.gridy = 0;
            contentPanel.add(txtX, gbc_txtX);
            txtX.setColumns(10);
        }
        {
            JLabel lblY = new JLabel("Y");
            GridBagConstraints gbc_lblY = new GridBagConstraints();
            gbc_lblY.anchor = GridBagConstraints.EAST;
            gbc_lblY.insets = new Insets(0, 0, 5, 5);
            gbc_lblY.gridx = 0;
            gbc_lblY.gridy = 1;
            contentPanel.add(lblY, gbc_lblY);
        }
        {
            txtY = new JTextField();
            GridBagConstraints gbc_txtY = new GridBagConstraints();
            gbc_txtY.insets = new Insets(0, 0, 5, 0);
            gbc_txtY.fill = GridBagConstraints.HORIZONTAL;
            gbc_txtY.gridx = 1;
            gbc_txtY.gridy = 1;
            contentPanel.add(txtY, gbc_txtY);
            txtY.setColumns(10);
        }
        {
            Component verticalStrut = Box.createVerticalStrut(20);
            GridBagConstraints gbc_verticalStrut = new GridBagConstraints();
            gbc_verticalStrut.insets = new Insets(0, 0, 5, 0);
            gbc_verticalStrut.gridx = 1;
            gbc_verticalStrut.gridy = 5;
            contentPanel.add(verticalStrut, gbc_verticalStrut);
        }
        {
            
            GridBagConstraints gbc_btnOuterColor = new GridBagConstraints();
            gbc_btnOuterColor.insets = new Insets(0, 0, 5, 0);
            gbc_btnOuterColor.gridx = 1;
            gbc_btnOuterColor.gridy = 6;
            contentPanel.add(btnOuterColor, gbc_btnOuterColor);
        }
        {
            
            GridBagConstraints gbc_btnInnerColor = new GridBagConstraints();
            gbc_btnInnerColor.gridx = 1;
            gbc_btnInnerColor.gridy = 7;
            contentPanel.add(btnInnerColor, gbc_btnInnerColor);
        }
        {
            JPanel buttonPane = new JPanel();
            buttonPane.setLayout(new FlowLayout(FlowLayout.RIGHT));
            getContentPane().add(buttonPane, BorderLayout.SOUTH);
            {
                JButton okButton = new JButton("OK");
                okButton.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent e) {
                        try {
                            int x=Integer.parseInt(txtX.getText());
                            int y=Integer.parseInt(txtY.getText());
                            validInput=true;
                        }catch(Exception exc){
                            JOptionPane.showMessageDialog(null, "Invalid values");
                        }
                    }
                });
                okButton.setActionCommand("OK");
                buttonPane.add(okButton);
                getRootPane().setDefaultButton(okButton);
            }
            {
                JButton cancelButton = new JButton("Cancel");
                cancelButton.addActionListener(new ActionListener() {
                    public void actionPerformed(ActionEvent e) {
                        validInput=false;
                        setVisible(false);
                    }
                });
                cancelButton.setActionCommand("Cancel");
                buttonPane.add(cancelButton);
            }
        }
    }
    
    public DlgShape(String title,Shape shape) {
        this();
        setTitle(title);
        setShape(shape);
        
        if(shape instanceof Point) {
            txtX.setText(String.valueOf(((Point)shape).getX()));
            txtY.setText(String.valueOf(((Point)shape).getY()));
            btnInnerColor.setVisible(false);
            btnOuterColor.setText("color");
            
        }else if(shape instanceof Line) {
            txtX.setText(String.valueOf(((Line)shape).getStartPoint().getX()));
            txtY.setText(String.valueOf(((Line)shape).getStartPoint().getY()));
            btnInnerColor.setVisible(false);
            btnOuterColor.setText("color");
        }else if(shape instanceof Rectangle) {
            txtX.setText(String.valueOf(((Rectangle)shape).getUpperLeftPoint().getX()));
            txtY.setText(String.valueOf(((Rectangle)shape).getUpperLeftPoint().getY()));
            
        }else if(shape instanceof Circle || shape instanceof Donut) {
            txtX.setText(String.valueOf(((Circle)shape).getCenter().getX()));
            txtY.setText(String.valueOf(((Circle)shape).getCenter().getY()));
        }
        
    }

}

and code for DlgRectangle, well DlgRectangle1 but lets call it DlgRectangle:

public class DlgRectangle1 extends DlgShape {

    private final JPanel contentPanel = new JPanel();

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        try {
            DlgRectangle1 dialog = new DlgRectangle1();
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.setVisible(true);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * Create the dialog.
     */
    public DlgRectangle1() {
        super();
        //this.getContentPane().add(new JLabel("widht"));
        
        
        
        JLabel lblWidth = new JLabel("width");
        GridBagConstraints gbc_lblWidth = new GridBagConstraints();
        gbc_lblWidth.anchor = GridBagConstraints.EAST;
        gbc_lblWidth.insets = new Insets(0, 0, 5, 5);
        gbc_lblWidth.gridx = 0;
        gbc_lblWidth.gridy = 2;
        contentPanel.add(lblWidth, gbc_lblWidth);
        
    }
    public DlgRectangle1(String title,Rectangle rectangle) {
        super(title,rectangle);
    }

}

Answer 1

I just needed to switch my properties in DlgShape from private to public or protected.

So

private JTextField txtX;
private JTextField txtY;
private JButton btnOuterColor = new JButton("outer color");
private JButton btnInnerColor = new JButton("inner color");

should be

public JTextField txtX;
public JTextField txtY;
public JButton btnOuterColor = new JButton("outer color");
public JButton btnInnerColor = new JButton("inner color");

Credits go to the comment by @Bohemian