Setting the height of a JTextFrame

问题

The following class creates a form (Jpanel) tasked with acquiring multiples Strings from the user and do something with them. It it functionally working, but it bugs me that the height of the JTextFields (a component that allows for the modification of one line of text) is automatically adjusted and can became extravagantly big.

I have tried the method setBounds(), but:

I do not want to calculate the position or width of the JTextField, just its height; and
It does not limit the height of the JTextField!

Any suggestion, please?

public class MultiplesStrings extends JFrame {

    /**
     * 
     */
    private static final long serialVersionUID = 1106317992372206473L;

    /** The greater {@link JPanel}.                                                                 */
    private JPanel contentPane;

    private JPanel[] interaction;
    private JLabel[] text;
    private JTextField[] insertText;


    /** The {@link JButton} that submits the form information.                                      */
    JButton button;

    @SuppressWarnings("unused")
    private Consumer<MultiplesStrings> instructions;

    // =========================================================            
        // TODO | Constructor

    /**
     * Create the frame.
     */
    public MultiplesStrings(String title, String[] messages, 
                int x, int y, int width, int height, 
                Consumer<MultiplesStrings> instructions) {

        // ===== MAIN FRAME DEFINITION =====

        this.setTitle(title);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setBounds(x, y, width, height);

        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(10, 10, 10, 10));
        setContentPane(contentPane);
        contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.PAGE_AXIS));
    //  contentPane.setBackground(Colours.newColor("DDDDDD"));

        // ===== INTERACTION FRAME DEFINITION =====

        this.interaction = new JPanel[messages.length];
        this.text       = new JLabel[messages.length];
        this.insertText = new JTextField[messages.length];
        for(int i=0 ; i<messages.length ; i++)
            {
            interaction[i] = new JPanel();
            interaction[i].setLayout(new BoxLayout(interaction[i], BoxLayout.LINE_AXIS));
            interaction[i].setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 0));
            interaction[i].add(Box.createHorizontalGlue());

            // ===== TEXT =====
            text[i] = new JLabel(messages[i]);
            text[i].setAlignmentY(RIGHT_ALIGNMENT);
        //  text.setBounds(0, imageResolution + margin, Width, buttonHeight);

            interaction[i].add(text[i]);

            // ===== INSERT TEXT FIELD =====
            insertText[i] = new JTextField();
        //  this.insertTextField.setBounds(Width + margin, imageResolution + margin, moveWidth, buttonHeight);
            insertText[i].setColumns(10);

            interaction[i].add(insertText[i]);

            this.add(interaction[i]);
            }

        // ===== SUBMIT BUTTON DEFINITION =====

        this.button = new JButton("Submit");

        // Button behavior
        MultiplesStrings support = this;
        button.addMouseListener(new MouseAdapter() {
            @Override
            public void mouseClicked(MouseEvent arg0) {         }
            } );
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent arg0) {     
                instructions.accept(support);       
        //      support.setVisible(false);
                }
            } );
        this.getRootPane().setDefaultButton(button);


        this.add(button);
    }

    // =========================================================            
        // TODO | Input-output manipulation

    /** Acquires all {@link String}s written by the user in the {@link JTextField}s used for {@code interactions}.  */
    public String[] acquireInputs() {
        String[] output = new String[interaction.length];
        for(int i=0 ; i<output.length ; i++)
            output[i] = insertText[i].getText();
        return output;
    }


    // =========================================================            
        // TODO | Main

    public static final int width   = 300;
    public static final int height  = 500;

    private static String[] input;

    /**
     * Launch the application.
     */
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() { public void run() {
            try {
                Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
                double screenWidth = screenSize.getWidth();
                double screenHeight = screenSize.getHeight();

                // Creates a centered form
                MultiplesStrings ms = new MultiplesStrings("Test", 
                    new String[] { "Insert first string: ", "Insert second string: ", "Insert third string: "},
                    (int) (screenWidth-width)/2,    (int) (screenHeight-height)/2, width, height, 
                    (MultiplesStrings obj) ->
                        {
                        input = obj.acquireInputs();
                        for(int i=0 ; i<input.length ; i++)
                            System.out.println("The " + i + "-th input is: " + input[i]);
                        }
                    );
                ms.setVisible(true); 

                } catch (Exception e) {         e.printStackTrace();                                }
        }
    });
}


}

回答1:

This is because BoxLayout uses the whole space of the container. With other words, it stretches all components to take the advantage of the total available space (since you use PAGE_AXIS, it refers to available height).

One of the solutions is to use a BorderLayout as an outside container and add this BoxLayout-ed panel inside at, with BorderLayout.PAGE_START constraints. PAGE_START constraints refers as "Hey you BoxLayout, there is no available space for you". Take a look at this example:

public class BoxLayoutSample extends JFrame {
    public BoxLayoutSample() {
        super("");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Container contentPane = getContentPane();
        contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));

        contentPane.add(new JTextField(15));
        contentPane.add(new JTextField(15));

        setLocationByPlatform(true);
        pack();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new BoxLayoutSample().setVisible(true));
    }

}

It gives us:

This is what you have by now.

But if you use an outside BorderLayout-ed panel:

public class BoxLayoutSample extends JFrame {
    public BoxLayoutSample() {
        super("");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        Container contentPane = getContentPane(); //This is the outer panel
        contentPane.setLayout(new BorderLayout());

        JPanel boxLayoutPanel = new JPanel(); //This is the nested panel
        boxLayoutPanel.setLayout(new BoxLayout(boxLayoutPanel, BoxLayout.Y_AXIS));

        //Components to nested panel
        boxLayoutPanel.add(new JTextField(15));
        boxLayoutPanel.add(new JTextField(15));


        //PAGE_START to wrap it on the top
        contentPane.add(boxLayoutPanel, BorderLayout.PAGE_START);

        setLocationByPlatform(true);
        pack();
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> new BoxLayoutSample().setVisible(true));
    }
}

You get:

Also, calling setBounds method to a component will be ignored if it contains a layout. In order to see setBounds effect you must container.setLayout(null) since the layout is responsible for the component's bounds. However, THIS IS NOT RECOMMENDED. INSTEAD USE LAYOUT MANAGERS. Let them work for you.

来源：https://stackoverflow.com/questions/61836188/setting-the-height-of-a-jtextframe

标签

java

swing

jtextfield