JTextField 在最小化时调整大小

我在 JFrame 中有一个 JTextField 和一个 JTextArea。但是，当应用程序运行时，如果我最小化窗口，JTextField 的大小就会调整。它的高度通常会增加一倍或三倍，但每次调整大小的方式并不一致。我不知道为什么会发生这种情况。我并不是真正要求直接的解决方案，只是要求一些可能导致问题的因素。如果你能在这里帮助我那就太好了。谢谢

编辑：这是我用来初始化它的代码：

public class Console extends JPanel implements ActionListener, Serializable {
    boolean ready = false;
    protected JTextField textField;
    protected JTextArea textArea;
    private final static String newline = "\n";
    Game m_game;
    Thread t;

public Console(Game game) {
    super(new GridBagLayout());

    m_game = game;
    textField = new JTextField(20);
    textField.setPreferredSize(null);
    textField.addActionListener(this);

    textArea = new JTextArea(20, 60);
    textArea.setEditable(false);
    textArea.setWrapStyleWord(true);
    textArea.setLineWrap(true);
    Font comic = new Font("Serif", Font.PLAIN, 14);
    textArea.setFont(comic);
    JScrollPane scrollPane = new JScrollPane(textArea);

    //Add Components to this panel.
    GridBagConstraints c = new GridBagConstraints();
    c.gridwidth = GridBagConstraints.REMAINDER;

    c.fill = GridBagConstraints.HORIZONTAL;
    c.fill = GridBagConstraints.BOTH;
    c.weightx = 1.0;
    c.weighty = 1.0;
    add(scrollPane, c);
    add(textField, c);
}

public void actionPerformed(ActionEvent evt) {
    String text = textField.getText();
    m_game.input = text;
    textField.selectAll();
    textArea.setCaretPosition(textArea.getDocument().getLength());
    m_game.wait = false;
    synchronized (m_game){
        ready = true;
        m_game.notifyAll();
    }
}

public void createAndShowGUI() {
    //Create and set up the window.
    JFrame frame = new JFrame("Game");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    //Add contents to the window.
    frame.add(new Console(m_game));

    //Display the window.
    frame.pack();
    frame.setVisible(true);
}

我认为它与布局管理器有关。http://docs.oracle.com/javase/tutorial/uiswing/layout/using.html http://docs.oracle.com/javase/tutorial/uiswing/layout/using.html