这个为什么会报红的，求解答，代码片第一行 public DataReceiver()和倒数11行frame.getContentPane().add(new DataReceiver());的DataReceiver

Question

class DataReceiver extends JPanel {
private List values; // 保存接收到的数据的容器.
private static final int MAX_VALUE = 200; // 接收到的数据的最大值.
private static final int MAX_COUNT_OF_VALUES = 50; // 最多保存数据的个数.

public DataReceiver() {
    values = Collections.synchronizedList(new ArrayList<Integer>());

    // 使用一个线程模拟产生数据.
    new Thread(new Runnable() {
        @Override
        public void run() {
            Random rand = new Random();

            try {
                while (true) {
                    addValue(rand.nextInt(MAX_VALUE)); // 产生一个数据，并模拟接收并放到容器里.
                    repaint();
                    Thread.sleep(100);
                }
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }).start();
}

@Override
public void paintComponent(Graphics g) {
    super.paintComponent(g);

    Graphics2D g2d = (Graphics2D) g;
    g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

    int w = getWidth();
    int h = getHeight();
    int xDelta = w / MAX_COUNT_OF_VALUES;
    int length = values.size();

    for (int i = 0; i < length - 1; ++i) {
        g2d.drawLine(xDelta * (MAX_COUNT_OF_VALUES - length + i),h-normalizeValueForYAxis(values.get(i), h),
                xDelta * (MAX_COUNT_OF_VALUES - length + i + 1),h-normalizeValueForYAxis(values.get(i + 1), h));
    }
}

/**
 * 接收到的数据放入内存.
 * @param value
 */
private void addValue(int value) {
    // 循环的使用一个接收数据的空间.
    // 最好是实现一个循环数组，而不是偷懒的使用ArrayList.
    if (values.size() > MAX_COUNT_OF_VALUES) {
        values.remove(0);
    }

    values.add(value);
}

/**
 * 规一化y轴方向的值. 使得value在y轴的值为[0, height]之间.
 *
 * @param value
 * @param height
 * @return
 */
private int normalizeValueForYAxis(int value, int height) {
    return (int) ((double) height / MAX_VALUE * value);
}

private static void createGuiAndShow() {
    JFrame frame = new JFrame("");
    frame.getContentPane().add(new DataReceiver());
    // Set frame's close operation and location in the screen.
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(400, 400);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);
}
public static void main(String[] args) {
    createGuiAndShow();
}

}

Answer 1

错误信息没有贴出来，你说的行号和代码也对不上啊。