我该如何访问这个该死的textArea？

Question

好的，这是我和我一起工作的班级。

问题出在write（）方法中，在那里我抛出了一个NPE ...我不明白如何访问这个文本区域，我只是想简单地添加文本到最后它！

public class chatBox extends JPanel implements ActionListener{
    protected static JTextField textField;
    protected static JTextArea textArea;
    private final static String newline = "\n";
    public static int tick = 0;

    public chatBox() {
        super(new GridBagLayout());

        textField = new JTextField(25);
        textField.addActionListener(this);

        textArea = new JTextArea(5, 25);
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea);

        //Add Components to this panel.
        GridBagConstraints c = new GridBagConstraints();
        c.gridwidth = GridBagConstraints.VERTICAL;
        c.weighty = 0.5;
        c.weightx = 0.5;

        c.fill = GridBagConstraints.VERTICAL;
        add(textField, c);
        c.gridx = 0;
        c.gridy = 0;

        c.fill = GridBagConstraints.VERTICAL;
        c.weightx = 0;
        c.weighty = 0.1;
        c.gridx = 0;
        c.gridy = 1;

        add(scrollPane, c);
    }

    public void actionPerformed(ActionEvent evt) {

        String text = textField.getText();

        textArea.append(Commands.cmd(text) + newline);
        textField.selectAll();

        //Make sure the new text is visible, even if there
        //was a selection in the text area.
        //textArea.setCaretPosition(textArea.getDocument().getLength());
    }

    public static void write(String wstr) {

        System.out.println("Writing " + wstr);
        textArea.append(wstr + newline);

    }

Answer 1

您需要创建一个chatBox对象才能初始化textArea。之后，您可以调用静态方法write。

或者您可以在静态块中初始化静态属性：

static {
    textArea = ....
}