JFrame：如何添加一个将新文本字段添加到框架的按钮？

Question

我对 Java 还是很陌生，我想自己动手做一个 GUI，但我似乎无法让它按照我想要的方式工作。

我写了一些代码，认为如果我按下 GUI 上的“添加”按钮，那么一个新的 JTextField 将出现在所有其他文本字段所在的下方，但这不会发生。只有一个新的 JTextField 确实出现了，但它出现在我的添加按钮旁边，而不是在我拥有的所有其他文本字段的下方，如果我再次按下它，什么也不会发生。我尝试使用其他变量，但它似乎无法正常工作。我觉得我的 ActionListener 出了点问题，但我不知道是什么。

public class TheGUI extends JFrame{
    List<JTextField> listOfTextFields = new ArrayList<JTextField>();

    private JTextField desc1;
    private JTextField instruct;
    private JTextField desc2;
    private JButton submit;
    private JButton addNew;

    public TheGUI() { //My GUI with the default fields & buttons that should be on there.
        super("Chili");
        setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();


        instruct = new JTextField("Choose your words");
        instruct.setEditable(false);
        c.fill = GridBagConstraints.HORIZONTAL;
        c.weightx = 0.5;
        c.gridx = 0;
        c.gridy = 0;
        add(instruct, c);

        addNew = new JButton("Add");
        c.weightx = 0.0;
        c.gridx = 1;
        c.gridy = 0;
        add(addNew, c);

        submit = new JButton("Submit!");
        c.weightx = 0.5;
        c.gridwidth = 2;
        c.gridx = 0;
        c.gridy = GridBagConstraints.PAGE_END;
        add(submit, c);

        desc1 = new JTextField(10);
        c.fill = GridBagConstraints.HORIZONTAL;
        c.weightx = 0.5;
        c.gridwidth = 2;
        c.gridx = 0;
        c.gridy = 1;
        add(desc1, c);

        desc2 = new JTextField(10);
        c.fill = GridBagConstraints.HORIZONTAL;
        c.weightx = 0.5;
        c.gridwidth = 2;
        c.gridx = 0;
        c.gridy = 2;
        add(desc2, c);

        addNew.addActionListener(new Adder());


        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(300,300);
        setVisible(true);

    }

    private class Adder implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent event) {

            int i = 0;
            listOfTextFields.add(new JTextField());
            GridBagConstraints textFieldConstraints = new GridBagConstraints();

             //Give it a max of 9 text fields that can be created.
            while(i < 10) {
                textFieldConstraints.fill = GridBagConstraints.HORIZONTAL;
                textFieldConstraints.weightx = 0.5;
                textFieldConstraints.gridx = 0;
                textFieldConstraints.gridwidth = 2;
                textFieldConstraints.gridy = 3 + i;
                i++;

            }

            add(listOfTextFields.get(i), textFieldConstraints);
            revalidate();
            repaint();


        }

    }


}

Answer 1

你的 while 循环真的很奇怪。

您的ActionListener 应如下所示：

 private class Adder implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent event) {
            if (listOfTextFields.size() == 9) {
                // Give it a max of 9 text fields that can be created.
                return;
            }

            JTextField textfield = new JTextField();

            listOfTextFields.add(textfield);
            GridBagConstraints textFieldConstraints = new GridBagConstraints();
            textFieldConstraints.fill = GridBagConstraints.HORIZONTAL;
            textFieldConstraints.weightx = 0.5;
            textFieldConstraints.gridx = 0;
            textFieldConstraints.gridwidth = 2;
            textFieldConstraints.gridy = 3 + listOfTextFields.size();

            add(textfield, textFieldConstraints);

            revalidate();
            repaint();

        }

    }