Java数据类型

public LineChartExample(String title) {
        super(title);
        // Create dataset
        DefaultCategoryDataset dataset = createDataset();
        // Create chart
        JFreeChart chart = ChartFactory.createLineChart(
                "Site Traffic", // Chart title
                "Date", // X-Axis Label
                "Number of Visitor", // Y-Axis Label
                dataset
        );

        ChartPanel panel = new ChartPanel(chart);
        setContentPane(panel);
    }