Java JTextField窗口大小

Question

Im trying to display to the user some text:

JTextField warningComponent = new JTextField(VERY_LONG_TEXT_NOENTERS);
warningComponent.setEditable(false);

but the window size is changed according to the text size. I want to set the window to be 30 X 40 all the time regardless of the warning text length. And i want the warning text to be adjusted to the window size (maybe the user will have to scroll to see the end) How do i do it? Maybe i should use other swing component? I tried most of the methods in JTextField class.

Thanks.

Answer 1

I add it to JPanel

Then the default layout manager should be a FlowLayout which will respect the preferred size of the text field.

To give a suggestion for the preferred size of the text field you need to do:

JTextField warningComponent = new JTextField(VERY_LONG_TEXT_NOENTERS, 20);

The second parameter will give a suggestion on how to size the text field to make approximately 20 characters visible at one time. You will then need to use the arrow keys to see the remaining characters.

Answer 2

And i want the warning text to be adjusted to the window size

If you want the textfield to resize according to the frame size and not the frame size following the dimension of the textfield, you may make use of specific layout to achieve that:

Using BorderLayout:

class MainPanel extends JPanel{

    private JTextField txt;

    public MainPanel(){
        setLayout(new BorderLayout());
        setPreferredSize(new Dimension(30, 40));
        txt = new JTextField();
        txt.setHorizontalAlignment(JTextField.HORIZONTAL);
        add(txt);
    }
}

Runner class to run to codes:

class TextFieldRunner{
    public static void main(String[] args){
       SwingUtilities.invokeLater(new Runnable(){
            @Override
            public void run(){
                JFrame frame = new JFrame("Text Runner");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);       
                frame.add(new MainPanel());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);             
            }
        });
    }
}

Answer 3

You can try JScrollPane in your application, JScrollPane is scroll-able horizontally and vertically as you wish. And add JTextArea to JScrollPane . JTextField is not scroll-able.

Here is a small example:

JScrollPane scrollPane = new JScrollPane();
JTextArea textArea = new JTextArea();
scrollPane.add(textArea);
scrollPane.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);

This is the values for the scroll policy:

VERTICAL_SCROLLBAR_AS_NEEDED
VERTICAL_SCROLLBAR_NEVER
VERTICAL_SCROLLBAR_ALWAYS
HORIZONTAL_SCROLLBAR_AS_NEEDED
HORIZONTAL_SCROLLBAR_NEVER
HORIZONTAL_SCROLLBAR_ALWAYS